BASELINE HUMAN HEALTH RISK ASSESSMENT

Baseline Human Health Risk Assessment

Operable Unit V
Peconic River

March 10, 2003

Prepared by
Environmental Management Directorate

Brookhaven National Laboratory
Upton, New York 11973

Table of Contents

Executive Summary
List of Tables
List of Figures
Acronyms, Abbreviations, and Units of Measure
1.0 Introduction
1.1 Previous Activities
1.2 Guidance Documents
2.0 Identification of Exposure Pathways and Potentially Exposed Populations
3.0 Constituents of Potential Concern
3.1 Data Sets
    3.1.1 Surface Soil
    3.1.2 Groundwater
    3.1.3 Surface Water
    3.1.4 Sediment
    3.1.5 Fish Tissue
    3.1.6 Deer Tissue
    3.1.7 Data QA/QC and Validation
3.2 Screening Procedures
3.3 Identification of COPCs
4.0 Exposure Assessment
4.1 Definition of Terms
4.2 Exposure Point Concentrations
4.3 Quantification of Exposure
    4.3.1 Current Conditions
    4.3.2 Future Conditions
4.4 Exposure Equations and Parameters
    4.4.1 Inhalation of Airborne Dusts and Particulates
    4.4.2 Incidental Ingestion of Soil
    4.4.3 Dermal Contact with Soil
    4.4.4 Ingestion of Groundwater
    4.4.5 Dermal Contact with Groundwater
    4.4.6 Inhalation of Groundwater
    4.4.7 Incidental Ingestion of Surface Water
    4.4.8 Dermal Contact with Surface Water
    4.4.9 Incidental Ingestion of Sediment
    4.4.10 Dermal Contact with Sediment
    4.4.11 Ingestion of locally Caught Fish
    4.4.12 Radionuclide Exposure
5.0 Toxicity Assessment
6.0 Risk Characterization
6.1 Non-Cancer health Hazards
    6.1.1 Groundwater
    6.1.2 Soil
    6.1.3 Fish
    6.1.4 Surface Water
    6.1.5 Sediment
6.2 Non-Radiological Cancer Risks
    6.2.1 Groundwater
    6.2.2 Soil
    6.2.3 Fish
    6.2.4 Surface Water
    6.2.5 Sediment
6.3 Total non-radiological Cancer Risks and Health Hazards
    6.3.1 Off-Site Resident Recreational Anglers
    6.3.2 Off-Site Recreational Anglers
    6.3.3 Off-Site Residents
    6.3.4 On-Site Trespassers
    6.3.5 Future On-Site Resident Recreational Anglers
    6.3.6 Future On-site Recreational Anglers
    6.3.7 Future On-Site Residents
6.4 Radiological Risk Assessment
    6.4.1 Ingestion of Surface Water
    6.4.2 Deer Meat Consumption
    6.4.3 Fish Consumption
    6.4.4 Ingestion of Groundwater
    6.4.5 Ingestion of Soil
    6.4.6 Ingestion of Sediment
    6.4.7 Inhalation of Airborne Dust and Particulates
    6.4.8 External Gamma Radiation
    6.4.9 Total Radiological Dose and Risk Assessment
6.7 Uncertainty
    6.7.1 Analytical Data
    6.7.2 Exposure Point Concentrations
    6.7.3 Exposure Factors
    6.7.4 Uncertainties in Toxicity Assessment
7.0 Summary and Recommendations
8.0 References
Appendix A - Risk Assessment Protocols for Operable Unit V Human Health Risk Assessment
Appendix B - RESRAD Output

Executive Summary

This risk assessment evaluates the potential human health risks to people that may now, or at some time in the future, be exposed to various contaminants that have been identified in the upstream areas of the Peconic River as a result of past operations at the U.S. Department of Energy’s Brookhaven National Laboratory. The assessment, which considers potential exposures for a reasonably maximally exposed individual under each of several scenarios, concludes that a human health risk from these contaminants may exist now and in the future if no action were to be taken. It is important to note that there are several uncertainties identified within the assessment that have a significant impact on the results of the calculations and should therefore be considered in determining any future actions.

The scenarios evaluated include the future resident living near the Peconic River, current off-site residents housed along the Peconic River, current residents and non-residents who are recreational anglers and hunters, and current on-site trespassers. Subsets of these scenarios include adult exposures, older child exposures and young child exposures as appropriate. This risk assessment augments prior risk assessments that have been completed with regard to the Peconic River. These areas are commonly referred to as Operable Unit V and the related documents are available in the Administrative Record.

The risks evaluated in this assessment are of two types. The first is a total cancer risk from all contaminants considered. The acceptable level of risk based upon the United States Environmental Protection Agency (EPA) is an excess risk of cancer that is not more than one in ten thousand to one in one million greater than that of the general population. The second type of risk is a non-cancer risk from the various contaminants through various pathways. This is measured through the use of a hazard quotient that is derived primarily through the use of EPA guidance documents. Additionally, for radionuclide exposure, a dose assessment that estimates the total radiological exposure is presented. Regulatory guidance addressing radionuclide contamination is often expressed in terms of annual dose. In using the guidance provided by the EPA, as well as input from other regulatory agencies such as the New York State Department of Environmental Conservation, the risk values calculated in this report represent a conservative estimate of risk for a reasonably maximally exposed individual.

This risk assessment proved to be particularly challenging because of the uncertainties that became evident as the assessment process was employed. In developing data sets for estimating risk, several difficulties were encountered where conservative assumptions in the absence of data were required or where reasonable assumptions could not be made leaving potential data gaps. The number and significance of the uncertainties associated with this risk assessment demanded that a broad spectrum of exposure scenarios be included. Incorporating a number of scenarios representing various populations created a range of risk estimates for consideration in determining the most appropriate remedial actions to be taken. Given the uncertainties, and the conservatism built into this assessment, the estimated risk for average individuals is likely to be much less than that calculated in this assessment.

This risk assessment will best be used as a tool to evaluate the risk under various scenarios, coupled with an objective measure (such as analysis of fish tissue contaminant concentration) to evaluate the success of remedial actions while minimizing ancillary damage to the wetlands and the surrounding ecosystem. Examples of the uncertainties incorporated into this risk assessment follow.

Among the pathways with the greatest risk, the most significant uncertainties revolve around fish, the influential contributor to the risk calculations for human health in the upstream Peconic River. There is an absence of data on actual fish consumption rates for fishing populations in the upstream portions of the Peconic River. This data gap results from a number of factual observations about the portion of the river upstream of Schultz Road. Over the past 35 years, the river upstream of Schultz Road has been dry in a cyclic fashion; often the river does not contain sufficient water for significant periods of time to support fish populations. Recent flow data indicate that this area was essentially dry about 30 to 40 percent of the time. Consequently, fishing in this area can only be sporadic at best. However, it is likely that portions of upstream sections of the river will carry water during the early portion of the summer months, which is typically a peak fishing period. During the periods in which the fish population can be sustained, particularly upstream on the BNL site, the fish are often much smaller than an edible or legal keeping size for fishermen.

Two additional studies are recommended and underway to reduce the uncertainty concerning the Peconic River water level variability and the impact of water level on the fish consumption pathway. The first study is an evaluation of historic Peconic River water levels in the upstream section of the river and a prediction of the range and frequency of future water levels. The second evaluation is a characterization of the fish habitat between the BNL Sewage Treatment Plant and Schultz Road and a prediction of potential fish biomass at low, mid, and high water levels. The results of these two studies will be placed in the Administrative Record on completion. The fish biomass evaluation will be placed in the Administrative Record as an attachment to this Risk Assessment, which may be modified if necessary.

Nonetheless, the assumptions in the risk assessment include a recreational angler taking sufficient fish from this part of the river to consume about 20 pounds a year per person (25 grams per day on average), and it assumes all 20 pounds per year is taken exclusively from this area of the Peconic River. Again, in the absence of data, this number is derived from a standard recreational angler consumption survey conducted by the EPA. It is not based upon Peconic River specific conditions. This number is accepted as valid for two reasons: there are no other data upon which to base risk, and there are insufficient fisherman observed in this area of the Peconic to develop a statistically valid survey.

Another key factor of uncertainty related to this aspect is the assumption that the upper section of the river is connected to the downstream section of the river by continuously flowing water so that the fish population can be replenished from the downstream section. Through observation over the past 35 years, the upper portion of the river often does not have sufficient water to support this assumption. This — coupled with an assumption that the water level in the future may be higher than present conditions thus leading to continuous flooding and a sustained fish population — leads to the 25 gram per day fish consumption value being used in this risk assessment. Additionally, a consumption rate of 6.5 grams per day (approximately five pounds per year) was also evaluated.

In addition to the uncertainties about the productivity of the river for recreational anglers, there is another aspect to the fish that creates sufficient uncertainty as to warrant notation. The fish samples in the upstream parts of the Peconic River have often been of insufficient size to evaluate them as edible portions. This has required the use of whole-body fish tissue data to represent the edible portion for human consumption. This adds a degree of uncertainty to the risk assessment. In particular, consumption of PCBs will be overestimated, though consumption of mercury may be underestimated.

Current off-site residents or recreational fishers may obtain fish from the Peconic River from on-site accessible areas of BNL. Data for contaminants in edible fish tissue from this area of the Peconic River are under-represented in the data set used for the off-site receptors. Since the concentrations of contaminants, particularly polychlorinated biphenyls (PCBs), were generally greater above the gauging station (maximum in whole fish samples of 6 parts per million [ppm] PCBs) than below the gauging station (maximum in edible fish tissue samples of 0.16 ppm PCBs), the exposure concentrations used to represent the edible fish tissue concentrations available to off-site receptors may have been underestimated. An analysis of the uncertainty due to this lack of data indicate that, for the off-site receptors, the non-cancer health hazard from fish consumption may be up to 2.5 times greater than calculated or the cancer risk from fish consumption may be almost ten times greater, but the health hazard and cancer risk would still be much less than that reported for a potential future on-site resident or recreational fisher.

Exposures to contaminants were assumed to potentially occur through incidental ingestion, dermal contact, and inhalation of soils and sediment. Exposure was also assumed to occur through incidental ingestion of surface water, dermal contact with surface water, consumption of groundwater as a drinking water source, dermal contact with groundwater during bathing, inhalation of volatile organic compounds from groundwater during showering, consumption of locally caught fish, consumption of locally caught deer, and external gamma radiation from cesium-137.

Constituents of potential concern that were assessed are: inorganics (arsenic, cadmium, chromium, copper, cyanide, iron, manganese, mercury, and thallium), volatile organic compounds (1,1-dichloroethene, 1,2-dichloroethane, ammonia, chloroform, tetrachloroethene, and trichloroethene), pesticides (DDD, DDE, DDT and alpha-chlordane), PCBs (Aroclor-1242, Aroclor-1254, and Aroclor-1260), polycyclic aromatic hydrocarbons (benzo(a)pyrene and benzo(b)fluoranthene), and radionuclides (americium-241, cesium-137, cobalt-60, lead-210, plutonium-238, plutonium-239/240, strontium-90, tritium, uranium-233/234, uranium-235, and uranium-238).

The evaluation of total cancer risks revealed that the total excess cancer risks to current off-site adult (2.1´ 10^-4) and young child (1.3´ 10^-4) residents, adult (1.4´ 10^-4) and young child (1.4´ 10^-4) resident angler/hunters, and adult non-resident angler/hunters (1.4´ 10^-4) that consume locally caught fish and deer were greater than the EPA acceptable range for excess risk of cancer of 1´ 10^-4 to 1´ 10^-6. That is, for a person meeting the conditions of the reasonably maximal exposed individual, the risk is greater than one in ten thousand. This is due to arsenic and trichloroethene in groundwater when used as a drinking water source and household supply, from cesium-137 in deer meat, and from polychlorinated biphenyls (PCB) in fish. Total excess cancer risks for off-site older children and off-site non-resident angler hunter younger children were all within the EPA acceptable range (9.0´ 10^-5 for older child resident angler/hunter, 2.5´ 10^-5 for young child non-resident angler/hunter, 3.1´ 10^-5 for older child non-resident angler/hunter, and 6.2´ 10^-5 for older child resident non-angler/hunter). This is also true of the current on-site trespasser with a total excess cancer risk of 1.2´ 10^-6.

The total cancer risk for on-site exposure to a future resident consuming locally caught fish or an on-site angler/hunter who meets the conditions of the reasonably maximally exposed individual, exceeds the acceptable risk range established by the EPA. This level of risk is mostly based upon exposure to PCBs, as measured in whole fish, as well as exposure to cesium-137 in deer meat. The total cancer risks for these on-site receptors are 1.2´ 10^-3 for adult resident angler/hunter, 5.4´ 10^-4 for young child resident angler/hunter, 4.6´ 10^-4 for older child resident angler/hunter, 1.1´ 10^-3 for adult non-resident angler/hunter, 4.9´ 10^-4 for young child non-resident angler/hunter, 4.4´ 10^-4 for older child non-resident angler/hunter, 3.2´ 10^-4 for adult resident non-angler/hunter, 2.8´ 10^-4 for young child resident non-angler/hunter, and 1.2´ 10^-4 for older child resident non-angler/hunter.

The total cancer risk for both current off-site and potential future on-site receptors not consuming locally caught fish or deer was significantly less. All were within the acceptable risk values established by the EPA.

In determining non-cancer risk, a hazard quotient value of 1.0 or less indicates that the risk is within an acceptable range; an organ or system specific value above 1.0 indicates that a person exposed consistent with the assumptions made may have an excess health hazard beyond what is considered acceptable by EPA criteria. The total non-cancer health hazard quotients for the following recreational angler adult and children scenarios, based on the assumptions for the reasonably maximally exposed individuals, exceeded 1.0: 5.0 for current off-site adult resident angler/hunter, 13 for current off-site young child resident angle/hunter, 9.1 for current off-site older child resident angler/hunter, 3.4 for current off-site adult non-resident angler/hunter, 7.9 for current off-site young child non-resident angler/hunter, 6.8 for current off-site older child non-resident angler/hunter, 62 for future on-site adult resident angler/hunter, 150 for future on-site young child resident angle/hunter, 120 for future on-site older child resident angler/hunter, 62 for future on-site adult non-resident angler/hunter, 140 for future on-site young child non-resident angler/hunter, and 120 for future on-site older child non-resident angler/hunter The primary contributor to these health hazards is the mercury as measured in edible fish tissue and PCBs as measured in whole-body fish tissue from on-site fish. Effects from mercury are primarily to the central nervous system, and effects from PCBs are generally to the immune system. The total non-cancer health hazard quotients for current off-site residents that are not recreational angler/hunters but may still consume locally caught fish are 2.5 for the adult, 9.6 for the young child, and 4.1 for the older child.

In addition to the contaminants in fish, arsenic and trichloroethene in groundwater contribute to the hazard quotient for the current off-site children. The hazard quotient for resident young children based on arsenic in groundwater in the off-site area is 1.7 and based on trichloroethene in groundwater is 2.2. However, arsenic in groundwater may likely be due to naturally occurring arsenic in soil and not related to site activities. Additionally, the concentrations of arsenic in groundwater are below the New York State groundwater standard of 25 micrograms per liter (m g/L) (6 New York Codes, Rules, and Regulations [NYCRR] Part 703), as well as the EPA’s established drinking water standard for arsenic of 10 m g/L. Arsenic may be related to naturally occurring arsenic within the soil of the region, and is not suspected to be site related. Trichloroethene has been detected in several monitoring well samples, as well as residential well samples, above the groundwater standard of five m g/L. An apparent trichloroethene plume has been identified in the Peconic River area. The groundwater in the area is classified as Class GA (fresh groundwaters) by the NYSDEC (6 NYCRR Part 701). Groundwater in the vicinity of the Peconic River is being addressed under Operable Unit (OU) V Record of Decision (BNL 2001a). To assure future safe drinking water, residents along the river in this area have been provided connection to the public water supply, and groundwater monitoring will continue. No further remedial action objectives are recommended for groundwater under OU V based on the results of this risk assessment.

Though this risk assessment evaluated exposure to cesium-137 through the consumption of potentially contaminated deer meat, it is likely that the elevated concentrations detected in deer are related more to other BNL on-site sources than to the Peconic River or OU V sources. Other sources that could result in cesium-137 in deer are being, or have been, remediated as part of Operable Unit I through the remediation of contaminated soils, which is designed to reduce the deer contamination. BNL also has an active deer monitoring program in place through which cesium-137 levels in deer are measured both on site and in off site areas. No further remedial action objectives that address deer contamination are recommended under OU V based on the results of this risk assessment.

In conclusion, for the reasonably maximally exposed individual, one who meets the assumptions made in this assessment with the established uncertainties, there is a potential for human health risk that exceeds the criteria established by the EPA. Therefore, it is recommended that remedial action objectives to address these risks be established and implemented on a timely basis to reduce this potential for risk to human health. Recommendations for additional actions include:

Evaluate the appropriateness of the fish consumption exposure factors for the on-site and off-site upstream portions of the Peconic River by evaluating the productivity of the river.
Evaluate the appropriateness of the site-specific fish consumption patterns.
Continue monitoring fish.
Continue monitoring deer.
Develop Remedial Action Objectives to address contaminated fish.
Evaluate potential future water levels and their frequency in the upper section of the Peconic River as a function of historic flow rates and water levels.
Evaluate potential fish biomass that the upper section of the Peconic River could support under low, high and mid water levels.

1.0 Introduction

This risk assessment evaluates the potential risks to human health for defined populations that may now, or at some time in the future, be exposed to various contaminants that have been identified in the upstream areas of the Peconic River as a result of past operations at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory (BNL). The assessment, which considers potential exposures for a reasonably maximally exposed individual under each of several scenarios, concludes that a human health risk from these contaminants may exist now and in the future if no action were to be taken. It is important to note that there are several uncertainties identified within the assessment that have a significant impact on the outcome of the calculations and should therefore be considered in determining any future actions.

The risks evaluated in this assessment are of two types. The first is a total cancer risk from all contaminants considered. The acceptable level of risk based upon United States Environmental Protection Agency (EPA) guidelines is an excess risk of cancer that is not more than one in ten thousand to one in one million greater than that of the general population. Cancer risks due to radiological contaminants are discussed in Section 6.4, cancer risk due to non-radiological contaminants are discussed in Section 6.2 and Section 6.3. The total cancer risk due to both radiological and non-radiological contaminants is presented in Section 6.5.

Additionally, for radionuclide exposure, a dose assessment that estimates the total radiological exposure is also presented in Section 6.4. Regulatory guidance addressing radionuclide contamination is often expressed in terms of annual dose.

The second type of risk is a non-cancer health hazard from the various contaminants through various pathways. This is measured through the use of a hazard quotient that is derived primarily through the use of EPA guidance documents. Non-cancer risks are discussed in Section 6.1.

In using the guidance provided by the EPA, as well as input from other regulatory agencies such as the New York State Department of Environmental Conservation (NYSDEC), the risk values calculated in this report represent a conservative estimate of risk for a reasonably maximally exposed individual. A list of these guidance documents is provided in Section 1.2.

This risk assessment proved to be particularly challenging because of the uncertainties that became evident as the assessment process was employed. In developing data sets for estimating risk, several difficulties were encountered where conservative assumptions in the absence of data were required. The number and significance of the uncertainties associated with this risk assessment demanded that a broad spectrum of exposure scenarios be included. Incorporating a number of scenarios representing various populations created a range of risk estimates for consideration in determining the most appropriate remedial actions to be taken. Given the uncertainties, and the conservatism built into this assessment, the estimated risk for average individuals is likely to be much less than that calculated in this assessment. These uncertainties are discussed in Section 6.7.

This risk assessment can best be used as a tool to evaluate the risk under various scenarios, coupled with an objective measure (such as analysis of fish tissue contaminant concentration) to evaluate the success of remedial actions while minimizing ancillary damage to the wetlands and the surrounding ecosystem.

Report Organization

Section 1.0 provides an introduction to this report. Section 2.0 presents an identification of the exposure pathways and potentially exposed populations that are addressed the baseline human health risk assessment. Section 3.0 addresses the constituents of potential concern (COPCs). The exposure assessment is presented in Section 4.0. This includes the quantification of exposure concentrations for the COPCs in the applicable media and the presentation of exposure factors for applicable. In Section 5.0, the toxicity of the COPCs is addressed, and the cancer slope factors and non-carcinogenic reference doses that are used in the risk assessment are presented. The risk characterization is presented in Section 6.0. This includes the presentation of media-specific non-carcinogenic health hazards and carcinogenic risks, an assessment of radiological risk and annual dose, and an evaluation across all media and pathways. Section 7.0 provides a summary and recommendations for remedial action objectives, and the references cited are included in Section 8.0.

1.1 Previous Activities

The Operable Unit V (OU V) Remedial Investigation (RI) Report (IT 1998) presented information on the nature and extent of contamination within OU V, including the Peconic River, and assessed the risk to human health and the environment. Since that report, additional samples of groundwater, surface water, soils, sediment, and fish have been collected for chemical and/or radiological analysis. Additional radionuclide data were reported in the Operable Unit V Plutonium Contamination Characterization and Radiological Dose and Risk Assessment Report (IT 2000), and a baseline human health risk assessment was prepared to present an estimation of potential carcinogen risks to human populations resulting from exposure to radionuclides associated with OU V currently and at some time in the future if no remedial action were to be taken at OU V. Risks from chemical contamination were not addressed in that report. Additionally, numerous sediment samples have since been collected from the Peconic River and measured for cesium-137 as part of the recent additional sediment characterization investigations. These data were presented in the Operable Unit V – Peconic River Analytical Results from the Supplemental Sediment Sampling Program Conducted September 4 – October 12, 2001 (BNL 2002).

Some of the receptors addressed in this risk assessment had been addressed in other risk assessments (IT 1998, 2000). The following summarizes those results as they pertain to the receptors to be addressed in the proposed risk assessment.

The 1998 RI Report evaluated an on-site trespasser in the current land-use scenario. The total non-radiological carcinogenic risk was 8 ´ 10^-7, within the EPA guidance range for carcinogenic risk. This risk was mostly due to arsenic in sediment, soil, and surface water. The total non-carcinogenic hazard was estimated as 0.14, with half of this due to incidental ingestion of sediment with mercury contamination. This health hazard is well within the EPA guidance for non-carcinogenic hazard of unity.

A future on-site resident was also evaluated in the RI Report. However, this resident was assumed to be housed at the sand filter beds/berms area of the Sewage Treatment Plant (STP), not along the Peconic River. The total carcinogenic risk to adult and child future residents was estimated as 5 ´ 10^-5 and 3 ´ 10^-5, respectively. The risk was predominantly from the ingestion of arsenic from all media, but mostly in groundwater. The total non-carcinogenic hazard to adult and child future residents was estimated at 1.8 and 4.9, respectively. The groundwater ingestion pathway contributed most to this hazard with most of that from manganese.

The RI Report included an evaluation of cancer risks and non-cancer health hazards from occasional consumption of fish from either on-site or off-site areas. The cancer risk and non-cancer health hazard for future on-site residents consuming on-site fish were both found to be above acceptable levels, with polychlorinated biphenyl (PCBs) being the principle risk driver. The cancer risk and non-cancer health hazard based on occasional consumption of off-site fish was found to be within acceptable levels; however, the off-site fish used in the risk assessment did not include any fish from off-site areas near the site, but included fish from Schultz Road and downstream to Peconic Lake and Forge Pond. The current off-site data set is more conservative because it only uses fish from on-site near North Street and downstream only as far as Schultz Road.

A subsequent radiological risk assessment (IT 2000) included a future on-site resident and an off-site resident in the upstream section of the Peconic River, as well as other receptors. The increased lifetime cancer risk to the future on-site resident was estimated as 3 ´ 10^-4. However, this risk was based almost entirely on external gamma radiation from the sand filter beds/berms area. (Cleanup of this contamination will be completed during the calendar year 2002.) The future on-site resident in the proposed risk assessment is assumed to be housed along the Peconic River, not on the sand filter beds/berms area. The increased lifetime cancer risk to the off site resident was estimated as 6.7 ´ 10^-5, which is within the EPA range of 1 ´ 10^-6 to 1 ´ 10^-4.

The objective of this risk assessment is to reassess the human health risks related to contamination in the Peconic River as a result of the additional chemical and radiological analyses. The scope of this risk assessment was developed following review by and discussions with EPA, NYSDEC, New York State Department of Health (NYSDOH), and Suffolk County Department of Health Services (SCDHS) personnel. The scope has been designed in an effort to address the concerns of those agencies so as to present a responsible and credible assessment. The scope of this risk assessment was presented in the Risk Assessment Protocols for Operable Unit V Human Health Risk Assessment, which is attached as Appendix A to this report. The tables from that report are not included within Appendix A since the tables are presented elsewhere in this document as part of the risk assessment report. (Note that the table numbers presented in the protocol document do not correspond with the table numbers for those tables as they are presented in the risk assessment report.) The Protocol document has been revised to provide additional clarity deemed necessary during the review process. In particular the following areas have been revised:

a data set used to represent off-site surface water is presented in Section 2.4
the deer data set has been defined in Section 2.7
additional detail regarding the radiological assessment, including dose and risk calculations have been added to Section 4.2.12

Additional information regarding procedures that were not sufficiently detailed within the Protocol document have been incorporated within the text of the risk assessment report.

In compliance with Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA) requirements, this risk assessment was prepared to present an estimation of potential carcinogenic risks and non-carcinogenic hazards to human populations resulting from exposure to chemical constituents originating from the Peconic River area of OU V, now and at some time in the future, if no remedial action were or will be taken (e.g., groundwater exposure is still assumed although public water hookups are in place in the affected area).

1.2 Guidance Documents

Procedures and methodologies used in the risk assessment are based on the following guidance:

Risk Assessment Guidance for Superfund, Volume I, Human Health Evaluation Manual-Part A (EPA 1989a)

Risk Assessment Guidance for Superfund, Volume I, Human Health Evaluation Manual (Part B, Development of Risk-Based Preliminary Goals) (EPA 1991a)

Risk Assessment Guidance for Superfund, Volume I, Human Health Evaluation Manual (Part D, Standardized Planning, Reporting, and Review of Superfund Risk Assessments) (EPA 1998)

Risk Assessment Guidance for Superfund, Volume I, Human Health Evaluation Manual (Part E, Supplemental Guidance for Dermal Risk Assessment) (EPA 2001)

Office of Solid Waste and Emergency Response (OSWER) Directive 9285.6-03, March 1991 (EPA 1991b)

Exposure Factors Handbook, Office of Research and Development, Washington, D.C. (EPA 1997a)

Health Effects Assessment Summary Tables (HEAST), Annual FY 1997 (EPA 1997b)

Risk Characterization Handbook (EPA 2000a)

Supplemental Guidance to RAGS: Calculating the Concentration Term (EPA 1992a)

The Lognormal Distribution in Environmental Applications (Singh, et al. 1997)

Risk Assessment Guidance for Superfund, Volume I, Human Health Evaluation Manual, Supplemental Guidance, "Standard Default Exposure Factors", Office of Solid Waste and Emergency Response (OSWER) Directive 9285.6-0 (EPA, 1991a)

Establishment of Cleanup Levels for CERCLA Sites with Radioactive Contamination, OSWER Directive 9200-4.18, (EPA, 1997c)

2.0 Identification of Exposure Pathways and Potentially Exposed Populations

Risk assessments must first identify what populations may be affected by potential risks in a specific area, both now and in the future.

Currently, the on-site portion of the Peconic River is primarily forest and wetlands. There are no on-site residents in the area, so residential exposure for on-site residents was not considered under the current land-use scenarios. There are, however, residents off-site along the section of the Peconic River from the site boundary to Schultz Road; those residents were considered in this assessment. Additionally, trespassers onto the site may currently be exposed to on-site contaminants, and were considered.

The future land-use assessment considered an on-site resident along the Peconic River at some point after loss of institutional controls for the site. BNL’s future land use plan (BNL 1995) presents the projected land use for a period of 20 years. The potential timing of the postulated closure and the level of development are indeterminate. Consistent with its application in other Operable Units at BNL (e.g., OU I), it is assumed that, at a minimum, it would be 50 years before the site were released and available for residential zoning. However, it is important to note that the assumption of the 50-year time frame is not implicit to any of the risk evaluations presented in this report. For example, exposure to radionuclides and chemicals by future residents, though in the future, is conservatively evaluated considering current concentrations and does not account for radioactive decay or other processes that may lead to natural attenuation.

Additionally, off-site residents may be potentially exposed to contaminants in the upstream section of the off-site Peconic River. However, because the potential risks to future off-site residents would be based on current data, the future off-site resident is not addressed separately.

Exposure to contaminants in groundwater may occur through drinking the water when using groundwater as a drinking water source, through inhalation of volatile contaminants when using groundwater to shower, and through dermal contact when using groundwater to bathe.

Exposure to contaminants in soil near the river may occur through direct contact, through inhalation of airborne soil particulates, through incidental ingestion of soil during daily activities, and (for radionuclides) through external radiation. The potential for exposure to contaminants through consumption of homegrown fruits and vegetables was evaluated for consideration in the risk assessment. The soils assessed in this risk assessment are assumed to represent a narrow area along the Peconic River. Their extent and location would not result in a significant exposure pathway through the consumption of homegrown fruit and vegetables; thus, this pathway was not evaluated in the risk assessment.

Exposure to contaminants in sediment in the river may occur through direct contact, through inhalation of airborne particulates when the river is dry, through incidental ingestion of sediment during activities at the river, and (for radionuclides) through external radiation when sediment is exposed.

Exposure to contaminants in surface water in the Peconic River may occur through direct contact and through incidental ingestion when engaged in activities at the river.

Exposure to contaminants in fish and deer may occur through the consumption of meat from locally caught fish and deer. Though contaminants in deer meat may be the result of exposures elsewhere on the BNL site — which are being addressed through remediation at other Operable Units — the exposure to contaminants in deer meat is addressed as part of the total exposure to receptors associated with the Peconic River.

The table below summarizes the potential exposure pathways and the population considered in this risk assessment. Tables 1.1 and 1.2 present this information in greater detail as part of the site conceptual model.

Exposure Scenarios Considered

	Current off-site resident	Future on-site resident	Current Off-Site Resident fisher/ hunter	Future On-Site Resident fisher/ hunter	Current Off-Site Non- resident fisher/hunter	Future Off-Site Non- resident fisher/hunter	Current On-Site Trespasser
Groundwater
Drinking	X³	X	X³	X
Dermal contact¹	X³	X	X³	X
Inhalation²	X³	X	X³	X
Soil
Ingestion	X	X	X	X	b	b	X
Dermal contact¹	X	X	X	X	b	b	X
Inhalation	X	X	X	X	b	b	X
External radiation¹	X	X	X	X	b	b	X
Sediment
Ingestion	X	X	X	X	b	b	X
Dermal contact¹	X	X	X	X	b	b	X
Inhalation	X	X	X	X	b	b	X
External radiation¹	X	X	X	X	b	b	X
Surface Water
Ingestion	X	X	X	X	b	b	X
Dermal contact¹	X	X	X	X	b	b	X
Fish
Consumption	X	X	X	X	X	X
Deer
Consumption			X	X	X	X

X = population considered
a = there are no on-site residents in OU V
b = considered insignificant compared to residential exposures
¹ Dermal uptake is not applicable for radionuclides due to small permeability constants and additional shielding factors, whereas external radiation is only applicable for radionuclides.
² Only inhalation of volatiles from groundwater is considered.
³ Exposure to groundwater is considered in the risk assessment although public water hookups have been provided in the affected area.

3.0 Constituents of Potential Concern

The purpose of the identification of the COPCs for use in the risk assessment is to focus the risk assessment process on the detected constituents that pose the greatest potential threat to human health. Section 3.1 defines the data sets that are used to represent the concentrations of constituents in the exposure media (e.g., surface soil, sediment). Section 3.2 describes the screening procedures used to select the COPCs. Section 3.3 presents the identified COPCs for each medium.

3.1 Data Sets

Chemical data from various environmental media were used in the previous baseline human health risk assessment: surface soil (0 to 6 inches), subsurface soil (0 to 12 feet), groundwater, surface sediment (0 to 6 inches), surface water, and fish. These data were fully validated by an independent contractor according to standard EPA procedures (1989a) to ensure that they were of suitable quality for use in the risk assessment. Since the baseline risk assessment, additional data have become available for some of these media. These data sets, as well as any additional data, are addressed in the following sections.

3.1.1 Surface Soil

Residents living along the Peconic River or trespassers to the BNL site near the Peconic River could be exposed to contaminants within the surface soils. These represent a relatively narrow band of soils adjacent to the Peconic River. Due to their limited area and their location next to the river, activities (e.g., construction) that would result in exposures to subsurface soils are unlikely. Because exposure to contaminants below the top six inches of soil is unlikely, data sets for concentrations in the top six inches were used for the human health risk assessment.

In general, soil samples had not been collected beyond the high water mark of the river up to the location or potential location of residential homes that would be representative of soil exposures to off-site or on-site riverside residents. However, several surface soil samples were collected in 2001 near the Peconic River in areas that may have received sediment removed from the river. These samples were collected near the STP discharge, near gauging station HM in Area A, and near gauging station HQ in Area D. Because these soil samples were collected from areas where it is suspected that sediment from the river may have been removed and placed on the nearby soil during construction activities related to the gauging stations, they were expected to be conservative estimates of average soil concentrations near the Peconic River. The data from these samples met all quality assurance/quality control (QA/QC) criteria, and these samples provide an additional surface soil data set: soils near the Peconic River. During the development of this risk assessment report, concerns were raised as to whether these were actually conservative estimates and whether soils nearer to residential homes may have higher cesium-137 concentrations from periodic flooding. In November 2002, several soil samples were collected along three transects extending from the high water mark of the river to the nearest residences. Cesium-137 was only detected in six of the fifteen samples, with the highest detected activity at 8 picoCuries per gram (pCi/g). These results were less than those reported for the soils near the gauging stations in Area A and Area D. No other data are available for soils, and not sediment, near the river. Thus, the on-site soil data set for this risk assessment consists of the soil data collected in Area A in 2001 and the off-site soil data set consists of the soil data collected in Area D in 2001.

3.1.2 Groundwater

Current and future off-site residents and potential future on-site residents could be exposed to contaminants in groundwater. Data representing groundwater in the area off-site and near the Peconic River and on-site near the Peconic River were used in this human health risk assessment.

The monitoring well groundwater data set used in the original risk assessment was used in this risk assessment. Groundwater samples from new and existing monitoring wells in the area have been collected as part of BNL’s annual monitoring program. The monitoring well data were evaluated to assure that they met the appropriate QA/QC criteria. The monitoring well data are considered most representative of potential drinking water exposures, and, with the addition of the more recent monitoring well data, provides a sufficiently large data set for use in the risk assessment.

The off-site groundwater data set used in the original risk assessment consisted of 65 off-site residential well samples collected and analyzed by the SCDHS. A formal risk assessment was not performed with this off-site groundwater data set; instead, the results of the individual well samples were compared to New York State or Federal drinking water standards.

For this risk assessment, the off-site groundwater data set consists of the results of samples collected from monitoring wells located near the eastern boundary of BNL in OU V and/or within the plume from OU V. This plume contains low-level volatile organic compounds (VOCs), primarily trichloroethene (TCE). The monitoring wells identified in the RI Report as AOC23-MW03 (061-04 and 061-05) are used for the off-site groundwater data set as well as monitoring wells, some more recently installed, sampled as part of the annual monitoring program (050-01, 050-02, 061-04, 061-05, 000-122, 000-123). (These wells are shown in Figure 2.) Additionally, SCDHS obtained data from a vertical profile monitoring well located off-site and within the OU V plume (identified as well MV-E within the data set). Data from this well are also included within the off-site groundwater data set. The data used for the off-site exposures were collected in 1995 as part of the RI, in 1999 as part of the Plutonium Contamination Characterization study, and up through 2001 as part of BNL’s annual monitoring program. Though the area defined by the groundwater data set has been provided public water hookups, the risk assessment assumes that off-site residents could use the groundwater as a drinking water and household-use source.

In evaluating risks due to use of groundwater as a household drinking water source, it is important to consider potential individual point sources (i.e., individual residential wells located at one point and at one general depth). Though the groundwater data used in this risk assessment are from wells that both characterize and delineate the potential contamination from OU V and the Peconic River, individual wells and well depths may have higher concentrations of some contaminants whereas other wells or depths may have higher concentrations of other contaminants. For example, the low-level VOC plume is located at a depth of approximately 200 feet below land surface (bls).

The data set contains data from monitoring wells located in the upper and lower portions of the deep aquifer. The range of these monitoring well screen intervals compare well with the range of screen intervals of domestic wells reported for the area. Data from monitoring wells located in the shallow aquifer were not used in the data set for this risk assessment since higher concentrations of contaminants were generally found below the shallow aquifer and the depths of these wells were less than the typical screen intervals of most domestic wells. The depths of the monitoring wells used for the OU V investigation are provided in the table below.

Upper Deep Aquifer		Lower Deep Aquifer
Well ID	Screen Interval (feet bls)	Well ID	Screen Interval (feet bls)
037-03	90-100	037-04	239-259
000-123	150-170	000-122	240-260
000-142	145-165	000-143	240-260
000-145	130-150	000-146	239-259
049-05	90-100	049-06	175-185
050-02	140-160	050-01	205-225
061-04	90-100	061-05	195-205
600-16	160-180	600-15	240-260
600-20	150-170	600-21	240-260
600-23	150-170	600-24	228-248
600-26	150-170	600-27	240-260

The potential uncertainty in the risk assessment concerning the use of the data from an extended area and various well depths is addressed in Section 6.7 of this report.

Results of the samples collected from on-site wells near the Peconic River in 1995 as part of the RI and in 1999 as part of the Plutonium Contamination Characterization study, as well as those collected up through 2001 as part of BNL’s annual monitoring program are used for the on-site groundwater data set in this risk assessment for exposures to potential future residents.

3.1.3 Surface Water

Current and future off-site residents, potential future on-site residents, and trespassers could be exposed to contaminants in surface water during activities in the Peconic River (e.g., swimming, wading). Thus, data representing concentrations of contaminants in the surface water either on-site or off-site were used in this human health risk assessment.

Nine surface water samples representing the surface water data set used in the previous risk assessment were located downstream of the STP discharge as far as the upper portion of Area C. On-site Area D contained no standing surface water during the period of surface water sample collections, and is often dry. Therefore on-site Area D is not represented in the on-site surface water data set. The on-site surface water data set used in this risk assessment consists of these nine surface water samples collected in 1995 as part of the RI.

Monthly data from 1972 to 1981 and from 1996 to 2001 indicate a yearly cycle that peaks around June and decreases through July and August and remains low (or no flow) throughout the early winter. Flow generally starts increasing in the January/February time frame. The 1996 to 2001 data indicate that flow generally stops around September or October and resumes in early winter. In dry years, it may stop in July or August. However, it is important to note that it is likely that portions of the upstream sections of the Peconic River (upstream) of Schultz Road will carry water during the early portion of the summer months, which is the peak fishing season.

Off-site Area D and Area E are also often dry, and did not contain water during most of the surface water sampling events. One sample was taken near Schultz Road during the RI Report Phase II sampling. However at that time, the Peconic River was dry from Area D on site until the confluence with the northern tributary to the Peconic River. Thus, the sample was not representative of surface water from the area. One sample was collected during the RI Report Additional Fish Tissue Study from on site near North Street, and one sample was collected from near Schultz Road. However, those were only analyzed for a limited number of contaminants, and only copper and lead were detected.

As part of BNL’s annual monitoring program, surface water samples have been collected periodically from gauging station HQ in Area D. Though the gauging station is on site, surface water passing through the gauging station is considered to be representative of surface water that could pass through the off-site Area D. In 2001, seven samples were collected between February and August. These data were used to represent the off-site surface water data set for this risk assessment.

3.1.4 Sediment

Current and future off-site residents, potential future on-site residents, and trespassers could be exposed to contaminants in sediment during activities in the Peconic River (e.g., swimming, wading). Thus, data representing concentrations of contaminants in the sediment water were appropriate for use in this human health risk assessment. Exposure to surface (top six inches) sediment is more likely than exposure to subsurface sediment. Therefore, surface sediment data was used.

The previous risk assessment used an on-site sediment data set consisting of the thirteen sediment samples collected from the top six inches of sediment collected from the on-site Peconic River extending from the STP to downstream of gauging station HQ near the BNL boundary. The risk assessment addressed potential on-site trespassers and future on-site residents that could be directly exposed to contaminated sediment in the on-site portion of the Peconic River (see Section 4.0 for further details). The applicable data (i.e., data that presents total concentrations in whole sediment and that have met appropriate QA/QC criteria) from the earlier studies were used in the reassessment. Additional sampling and analysis was conducted as part of the Supplementary Peconic River Sediment Sampling in September 2001 (BNL 2002), and was designed to fill gaps in the existing data necessary to better define the nature and extent of sediment contamination both on and off site. This consisted of 108 surface sediment samples collected on site and 49 surface sediment samples collected off site between the BNL boundary and an area just downstream of Schultz Road. These data were reviewed and validated to assure that they met the appropriate criteria, and the data from this sampling were used in the risk assessment for both on-site and off-site sediment data sets along with the data addressed in the previous paragraph.

Because the samples from the area just downstream of BNL (Area D) had higher levels of most contaminants in the sediment than areas further downstream (Areas E and P, for example), and because exposures to contaminants near where residents live are more likely to occur with more frequency, the data from Area D were used to represent the off-site sediment for evaluating potential exposures.. For example, the maximum concentration of cesium-137 in Area D was 17.4 pCi/g, whereas the maximum in Area E and Area P were 24.1 pCi/g and 22 pCi/g, respectively. Average concentrations for Area D or Area D extended to the maximum concentration in Area E were similar (7.9 pCi/g and 8.5 pCi/g, respectively). Average concentrations for other contaminants would decrease if the exposure area were increased (e.g., 12.4 milligrams per kilogram [mg/kg] to 10.5 mg/kg for mercury and 102 m g/kg to 92 m g/kg for Aroclor-1254, respectively).

Thus, the on-site sediment data set consists of the surface sediment data collected in 1995, 1996, and 1997 as part of the RI, in 1999 as part of the Plutonium Contamination Characterization study, and in 2001 as part of the Supplementary Peconic River Sediment Sampling. The off-site sediment data set consists of the surface sediment data collected from the off-site Area D in 1996 as part of the RI, in 1999 as part of the Plutonium Contamination Characterization study, and in 2001 as part of the Supplementary Peconic River Sediment Sampling.

The sediment data for both the on-site and off-site receptors included data from sediment that was usually covered with water, sediment that is often dry, and sediment that was only rarely wet. For certain exposure pathways (e.g., external gamma radiation), it was necessary to further divide the data into these subsets in order to assess total exposure.

3.1.5 Fish Tissue

People who consume fish from the Peconic River could be exposed to contaminants in the edible portions of those fish. Off-site residents or anglers can easily access the on-site portion of the Peconic River near North Street. Thus, it is appropriate to use the off-site edible fish tissue data from and including the on-site portion of North Street to Schultz Road for the risk assessment for current potential exposures, whereas it is appropriate to use the on-site edible fish tissue data from the STP down to and including North Street for the risk assessment for future potential exposures only.

A total of 97 fish tissue samples were collected in 1997 and analyzed as part of the Additional Fish Tissue Study. The report was presented as Appendix F.4 of the RI Report and was used in the original human health risk assessment. All fish collected during that study were analyzed as whole body samples (i.e., skin, scales, head, fins, viscera, bones, were all included in the sample), not as edible fish tissues. This was considered appropriate for assessing risks to wildlife that would consume whole fish, and it was considered conservative for assessing risks from organic contaminants to human health when only edible tissues are usually consumed. Lipophilic contaminants, such as PCBs, accumulate mainly in fatty tissues: belly flap, lateral line, subcutaneous and dorsal fat, dark muscle, gills, eyes, brain, and internal organs (EPA, 2000b). Many of these tissues are not typically consumed by humans. Contaminant concentration ratios between whole body samples and standard fillet samples have been reported to be greater than one (Parkerton et al., 1993; Nimmi and Oliver, 1989). Conversely, risks due to mercury may actually be underestimated when using whole body data (EPA 1997d). A total of 36 fish were collected from on-site areas and used to represent the on-site fish data set. A total of 37 fish were collected from off-site areas of the Peconic River and used to represent the off-site fish data set.

In 1996, fish were also collected from the on-site Peconic River and analyzed for chemical and radiological constituents. The results were reported in the Fish Tissue Bioaccumulation Study Report that was contained as Appendix F.3 of the RI Report. All fish were small (generally less than six inches in length) and were prepared by beheading and eviscerating. Composite samples were prepared representing the same species from the same location. These also were not prepared as edible fish tissue samples. Though most samples were analyzed for metals, only four samples were analyzed for organic contaminants. Fish have also been collected in the Peconic River on site as part of BNL’s annual monitoring program. These fish were treated as whole body samples due to the small size of the fish. The fish data from the 2000 Site Environmental Report (BNL 2001) and the 1999 Site Environmental Report (BNL 2000) provide data for a total of six fish samples from on site that were analyzed as whole body samples. The off-site fish data used in the baseline risk assessment reported in the RI Report were from fish collected from an area near Schultz Road, an area near Manor Road, Donahues Pond, and Forge Pond, and, therefore, represented a large off-site area. These fish were collected as whole body samples and not edible fish tissue. Thus, they were considered to be conservative estimates of actual exposure to organic contaminants and potentially under-estimates of actual exposure to mercury.

In June and July 2001, fish were collected from off-site areas downstream of gauging station HQ as far as the Schultz Road area by NYSDEC personnel. These fish were not tested as whole fish samples. Instead, larger fish were prepared as edible fillets, and smaller fish were beheaded and eviscerated, in accordance with EPA guidance (EPA 2000b). Edible fish data are preferred because they most accurately measure the potential exposure concentrations for people eating fish, and edible fillet concentrations and whole body concentrations are often drastically different. In fact, the edible fish tissue data from the North Street area and the Schultz Road area collection 2001 were compared to the data from the fish previously collected from the same areas that were tested as whole body samples. Concentrations of mercury, Aroclor-1254, dichlorodiphenyldichloroethane (DDD), dichlorodiphenyldichloroethene (DDE), and dichlorodiphenyltrichloroethane (DDT) from the 1997 and 2001 collections were compared statistically and, as expected, were found to be statistically significantly different. The pesticides and PCBs, which partition to fatty tissues, were found to be significantly lower in the edible portions from 2001 than in the whole fish from 1997. In accordance with EPA guidance (2000b), edible fish tissue data should be used in the risk assessment. Thus, the recently collected fish tissue data from 2001 were used as the off-site fish data set in this human health risk assessment.

Though the fish collected on-site and upstream of the gauging station HQ were all analyzed as whole body samples, the data were used as estimates of on-site exposures because adequate edible portion sample data are not available for on site. These are likely to overestimate exposures to organic contaminants such as PCBs but may underestimate exposures to mercury. The data from the 1997 and 1996 collections, which constitute the bulk of the on-site data, as well as the data from the six samples collected as part of the annual monitoring program (BNL 2000, 2001), were used in the on-site fish tissue data set.

Since edible-portion sample data are not available for on-site fish except for the on-site Area D below the gauging station, whole-body sample data from the STP to on-site Area D above the gauging station were used. This provided a conservative estimate of on-site exposures for most organic contaminants in the edible portion of those fish, but may underestimate the mercury concentrations in the edible tissue of those fish. The data from the 1997 and 1996 collections and the data from the annual monitoring program were also used in the on-site fish tissue data set. Thus, the data set for fish used for potential future on-site exposure consists of whole-body data from on-site areas from Area D to the STP collected in 1996 and 1997 as part of the RI and from 1999 and 2000 as part of BNL’s annual monitoring program.

The data set for fish used for evaluating exposure by off-site residents and anglers consists of edible fish tissue data from the Peconic River Area D near North Street to Schultz Road collected in 2001 as part of BNL’s annual monitoring program. No edible fish tissue data were available for the on-site Area D above the gauging station, an area that is easily accessible to off-site receptors. Based on the concentrations of organic contaminants (particularly PCBs) measured in whole body samples from on-site Area D above the gauging station, it is expected that the edible fish tissue concentrations would be higher than those reported in the edible fish tissue data from below the gauging station. The lack of edible fish tissue data from the on-site Area D above the gauging station is addressed in Section 6.7 with regard to the potential uncertainty in the risk assessment.

For the most part, fish collected upstream of Schultz Road, particularly in the on-site upstream area, are generally small but have included a few sufficiently large fish to provide for fillets. Data from an ongoing investigation will be used to predict future fish size and biomass relative to water level in the Peconic River and similar streams.

3.1.6 Deer Tissue

Samples of deer tissue are routinely collected by BNL from on-site, off-site, and remote areas. These samples have been analyzed for select radionuclides, including cesium-137. Data from these samples are reported within BNL’s annual Site Environmental Reports (BNL 2001, 2000, 1999, 1998, 1997).

For the purposes of this risk assessment, a deer tissue data set for was used to evaluate exposures to hunters that obtain deer near BNL. Analysis of deer meat has been conducted for cesium-137. Analysis for other bioaccumulatable contaminants (e.g., mercury, cadmium, PCBs) has not been conducted. Thus, only exposures to cesium-137 can be quantitatively evaluated. The foraging range of deer is typically one square mile (Grund et al. 2002). It is reasonable and conservative to assume that any deer found within one mile of OU V or the off-site upstream section of the Peconic River may represent cesium-137 levels derived from OU V sources or the Peconic River. However, in non-optimal conditions, deer may range further for food and shelter. Deer with elevated cesium-137 levels have been found at further distances from BNL, and accumulation of cesium-137 in deer meat may occur from other areas of the BNL site besides the Peconic River. Since, the average cesium-137 levels in deer on the BNL site (2.4 pCi/g), on or within one mile of the BNL site (2.4 pCi/g), and on or within 10 miles of the BNL site (2.2 pCi/g) were similar, for the purpose of this risk assessment, the deer tissue data set contains data from deer collected from on the BNL site up to a distance of 10 miles.

Background deer tissue samples were considered to be those flesh or meat samples from deer collected 10 to 40 miles from BNL. Those deer are assumed to be representative of background cesium-137 levels. The data collected from background areas from 1996 to 2001 were used to define the background deer meat data set. The average concentration in these deer was 0.6 pCi/g.

The deer collected since 1992 and reported in the Site Environmental Reports were used to define the cesium-137 deer tissue data set for this risk assessment. Additionally, the Site Environmental Report contains data for non-edible tissues (e.g., bone) and other edible tissues (e.g., heart and liver), as well as standard meat, or flesh, samples. Since the hunter’s dietary intake is largely flesh samples and not organ meats, the data for the heart and liver (which generally showed lower cesium-137 levels than flesh samples) were not used in the data set to avoid biasing the data inappropriately toward the activities measured in the heart and liver.

The bioaccumulation of cesium-137 in deer is likely due more to other BNL sources than from the Peconic River. The remediation of soil as part of Operable Unit V is designed, in part, to address this bioaccumulation and reduce cesium-137 concentrations in deer. Regardless, the deer meat data set has been defined so as to address the total exposure with which receptors who are associated with the Peconic River area may come in contact.

3.1.7 Data QA/QC and Validation

Analytical data quality was assured through the use of standard field sampling and analytical laboratory procedures that were reviewed and approved by EPA and NYSDEC. All chemical and radiological data were validated to further assure the quality of the data. Data validation is a specific data evaluation process that examines adherence to EPA’s performance-based acceptance criteria. The analytical data validation process consisted of ensuring analytical data quality through the use of standard field sampling and analytical laboratory procedures, specifically evaluation of data completeness, verification of instrument calibration, measurement of laboratory precision using duplicate samples, measurement of laboratory accuracy using spikes, examination of blanks for contamination, assessment of adherence to method specifications and QC limits, and evaluation of method performance in the type of sample matrix.

3.2 Screening Procedures

It is important to focus on constituents that have the potential to cause the greatest risk. Screening procedures are used to limit the number of constituents of potential concern in each medium (EPA 1989a). Three screening procedures are used for the risk assessment data sets to assure that the proper contaminants are being assessed. The methodology for the screening procedures used in this risk assessment are addressed in the following paragraphs.The first level of screening is an evaluation of the frequency of detection in each of the data sets. Constituents that are infrequently detected may be artifacts in the data due to sampling, analytical, or other procedures and, therefore, may not be related to site operations or disposal practices. For this risk assessment, a constituent detected in five percent or fewer samples in any given environmental medium (e.g., groundwater, soil, fish) was omitted from the quantitative risk assessment for that medium. In addition, constituents that are considered essential nutrients, such as aluminum, calcium, sodium, magnesium, potassium and iron, were excluded.

The second level of screening that was applied to each of the data sets was a comparison method. For the comparison method, the maximum concentration detected in a medium or data set was compared to screening values. Region II of the EPA recommends the use of the Region IX Preliminary Remediation Goals (PRGs) as the appropriate screening values. These PRGs are based on generic residential exposure assumptions and either a hazard index of 1/10 or a cancer risk of 1 ´ 10^-6 (a one in one million increased cancer risk). However, constituents that are known human carcinogens (Group A) were retained as COPCs if they exceeded screening values, regardless of the frequency of their detection. The Region IX PRGs were developed in 2000 and updated in 2002; the PRGs were reviewed prior to use in screening to assure that the most recent toxicity data were used in the development of the PRGs. PRGs were recalculated for those constituents for which toxicity data had changed since the development of the revised PRGs.

The third level of screening applies only to radionuclides. Region IX PRGs are not available for radionuclides. Instead, the maximum detected radionuclide activity in a particular medium was compared to the background activity for that radionuclide. If the maximum activity of that radionuclide was below that of the background, that radionuclide was not retained as a COPC for that particular medium. Since cancer risks are determined as the increased lifetime cancer risk above background, this screening procedure is appropriate. Background reference activities of selected radionuclides in soil were identified in the OU I RI Report. Additional data had been collected and reported in the Plutonium Contamination Characterization and Dose and Risk Assessment Report for other media and other radionuclides. Additionally, detected radionuclides with half-lives less than 6 months are also not considered in this risk assessment. The potential risk due to these radionuclides is incorporated in the slope factors for their parent radionuclides. Radium-226, which had been reported in some groundwater samples and was analyzed using gamma spectroscopy, was also eliminated as a COPC. Gamma spectroscopy is known to grossly overestimate, or misidentify, radium-226. Subsequent isotope specific analysis for radium-226, with lower detection limits, found no detectable levels of radium-226. For those radionuclides identified as COPCs, the activities used in the risk assessment are the measured exposure point concentrations minus the average background activities. In this way, the calculated risk is the incremental lifetime cancer risk above background.

Lead detected in environmental media at OU V has been addressed as follows. The EPA has not derived a carcinogenic slope factor or a non-carcinogenic reference dose for lead. The EPA recommends using the "Integrated Exposure Uptake Biokinetic Model for Lead in Children" for soil levels above 400 mg/kg and groundwater concentrations above the EPA action level of 15 micrograms per liter (µg/L). The highest soil concentration reported for OU V is 95.5 mg/kg, less than a quarter of the action level. Soils near the Peconic River were even less, with a maximum of 22.4 mg/kg. A further assessment of lead in soil was unnecessary. The Adult Lead Model (EPA, 1996a) indicates that the concentration in soil associated with adult exposures and impacts on the developing fetus range from 750 mg/kg to 1,750 mg/kg. Thus, the 400 mg/kg screening level is also protective of adults. The highest concentration in sediment reported in the OU V RI Report was 120 mg/kg. The highest concentration of lead in sediment was 214 mg/kg, which is below the action level. Based on this information, no further assessment of lead in sediment is necessary. The groundwater data set used from on site near the Peconic River used to evaluate potential off-site exposures had a maximum concentration of 3.2 µg/L and that for on-site future residential exposures had a maximum concentration of 1.4 µg/L. A further assessment of lead in groundwater was unnecessary.

3.3 Identification of COPCs

The results of the screening procedures for COPCs are presented in Table 2-1 through Table 2-11. Each table presents a summary of the occurrence, distribution, and selection of COPCs. The frequency of detection is listed as well as the minimum and maximum detected concentrations. The screening toxicity value is presented as well (e.g., the Region IX PRG) as additional information regarding other potential regulatory values. The last two columns indicate whether the constituent was considered to be a COPC for the risk assessment or not and the reason for its inclusion or exclusion.

Groundwater: For on-site groundwater, three inorganics, three VOCs, and four radionuclides were identified as COPCs: arsenic, manganese, thallium, 1,1-dichloroethene, chloroform, trichloroethene, plutonium-238, strontium-90, tritium, and uranium-233/234. For off-site groundwater, four inorganics, six VOCs, and four radionuclides were identified as COPCs: arsenic, cyanide, iron, manganese, 1,1-dichloroethene, 1,2-dichloroethane, ammonia, chloroform, tetrachloroethene, trichloroethene, plutonium-238, tritium, uranium-233/234, and uranium-238.

Surface soil: The only COPCs identified for on-site and off-site surface soil adjacent to the Peconic River were arsenic and cesium-137. Though arsenic in off-site soil was below the background concentration, it was still retained as a COPC.

Sediment: COPCs for on-site sediment were polychlorinated biphenyls (PCB), polycyclic aromatic hydrocarbons (PAH), inorganics, and radionuclides: Aroclor-1254, benzo(a)pyrene, benzo(b)fluoranthene, arsenic, mercury, americium-241, cesium-137, cobalt-60, lead-210, plutonium-238, plutonium-239/240, strontium-90, uranium-233/234, uranium-235, uranium-238, and tritium. Off-site sediment COPCs included arcolor-1254, arsenic, chromium, mercury, americium-241, cesium-137, plutonium-238, plutonium-239/240, and uranium-235.

Surface water: Arsenic, chloroform, cyanide, thallium, americium-241, tritium, uranium-233/234, and uranium-235 were identified as on-site surface water COPCs. Arsenic, uranium-233/234, and uranium-235 were also identified as off-site surface water COPCs.

Fish: COPCs in on-site fish are 4,4-DDD, 4,4-DDE, alpha-chlordane, Aroclor-1254, Aroclor-1260, arsenic, cadmium, copper, mercury, americium-241, cesium-137, strontium-90, uranium-234, uranium-235, and uranium-238. Mercury in fish is conservatively assumed to be all methyl mercury. Off-site fish COPCs are 4,4-DDD, 4,4-DDE, 4,4-DDT, Aroclor-1242, Aroclor-1254, mercury, cesium-137, and strontium-90. It should be noted that the analysis conducted on fish used for assessing the off-site receptors reported combined concentrations of Aroclor-1254 and Aroclor-1260. Since toxicity information is available for either total PCBs or Aroclor-1254, but not for Aroclor-1260, the reported concentrations were conservatively assumed to be all Aroclor-1254.

Deer: Deer meat samples have not been analyzed for non-radiological constituents. Deer meat was analyzed for cesium-137 due to the presence of cesium-137 in media throughout the site that may lead to uptake by plants on which deer might feed and due to the potential for cesium-137 to partition to the flesh instead of non-edible tissues. Other bioaccumulative contaminants such as PCBs or mercury are limited in their distribution (i.e., found in Peconic River sediment) and are unlikely to provide a significant source to deer. Therefore, only cesium-137 is identified as a COPC for deer meat.

4.0 Exposure Assessment

The Risk Protocols (found in Appendix A) define the assessment process. After samples were collected, the sample data were used as outlined in the protocols to determine exposures. The objective of the exposure assessment is to quantify the type and magnitude of the total exposure by potential receptors to COPCs that are present at, or migrating from, BNL, or are present off site but may be due to BNL activities, currently or at some time in the future if no further remedial actions were to be taken. The potentially exposed populations and exposure pathways to environmental media (e.g., soil, surface water, sediment, and groundwater) were identified in Section 2.0. Section 4.1 presents a list of some technical terms that are used within the exposure assessment. In Section 4.2, the statistical analyses that are used to determine a conservative exposure point concentration (EPC) are presented. Section 4.3 identifies the exposure pathways for each of the potential receptors being evaluated. In Section 4.4, the equations that are used to determine the Chronic Daily Intakes (CDI) of non-radiological COPCs and the total radiological intake and annual dose are presented, along with the exposure factor assumptions.

4.1 Definition of Terms

Some technical terms are used in this section of the document. Following is a brief explanation of what these terms mean, and how they are used.

Central Tendency Exposure (CTE): A risk descriptor representing the average or typical individual in a population, usually considered to be the mean or median of the distribution.

Chronic Daily Intakes (CDI): Exposure expressed as mass of a substance contacted per unit body weight per unit time, averaged over a long period of time (as a Superfund program guideline, seven years to a lifetime).

Exposure Point Concentration (EPC): The contaminant concentration within an exposure unit to which receptors are exposed. Estimates of the EPC represent the concentration term used in exposure assessment.

Hazard Index (HI): The sum of hazard quotients for substances that affect the same target organ or organ system. Because different pollutants may cause similar adverse health effects, it is often appropriate to combine hazard quotients associated with different substances.

Hazard Quotient (HQ): The ratio of a single substance exposure level over a specified time period (e.g., subchronic) to a reference dose (or concentration) for that substance derived from a similar exposure period.

Reasonable Maximum Exposure (RME): The highest exposure that is reasonably expected to occur at a site. The intent of the RME is to estimate a conservative exposure case (i.e., well above the average case) that is still within the range of possible exposures.

Reference Concentration (RfC): The RfC is an estimate (with uncertainty spanning perhaps an order of magnitude) of a continuous inhalation exposure to the human population (including sensitive subgroups which include children, asthmatics and the elderly) that is likely to be without an appreciable risk of deleterious effects during a lifetime. It can be derived from various types of human or animal data, with uncertainty factors generally applied to reflect limitations of the data used.

Reference Dose (RfD): The RfD, like the RfC, is an estimate of the amount of exposure to which a person (including sensitive subpopulations) could be exposed to on a daily basis where adverse noncarcinogenic health effects (e.g., organ damage, biochemical alterations, birth defects) would not be expected.

Slope Factor (SF): A plausible upper-bound estimate of the probability of a response per unit intake of a chemical over a lifetime. The slope factor is used to estimate an upper-bound probability of an individual developing cancer as a result of a lifetime of exposure to a particular level of a potential carcinogen.

Upper Confidence Limit (UCL): The Upper Confidence Limit is the upper bound of a confidence interval around any calculated statistic, most typically an average. For example, the 95 percent confidence interval for an average is the range of values that will contain the true average (i.e., the average of the full statistical population of all possible data) 95 percent of the time.

4.2 Exposure Point Concentrations

Statistical analyses were performed to verify the distribution of contaminants in environmental media at the Peconic River and to determine a typical concentration for each constituent in each medium. The first step was to determine the appropriate statistical distribution (i.e., normal or log-normal) that the data represented. This was accomplished by using the W-test or D’Agostino’s Test depending on the size of the data set (Gilbert 1987). The W-test was developed by Shapiro and Wilk (1965) and is used for testing whether a data set is from a normal distribution. By conducting the test on the log-transformed data, it is equally effective for testing whether a data set is from a log-normal distribution. The W-test is used for data sets with fewer than 50 data points. D’Agostino’s test (D’Agostino 1971) is used for testing for normality or log-normality for data sets with greater than fifty elements.

For quantitative human health risk assessments, the EPC — which is the concentration term used in the exposure equations — is the arithmetic average of the concentration that is contacted over the exposure period. It is estimated from the arithmetic average concentration for a contaminant based on a set of sampling results. Because of the uncertainty associated with estimating the true average concentration at a site, the 95 percent upper confidence limit (UCL) of the arithmetic mean was used for this variable for the reasonable maximum exposure (RME). The 95 percent UCL provides reasonable confidence that the true site average concentration will not be underestimated. The arithmetic average concentration is used for the central tendency exposure (CTE). For normal and log-normal distributions, the UCL was calculated according to the following equations:

For normal distributions

where
UCL = upper confidence limit
x = mean of the un-transformed data
s = standard deviation of the un-transformed data
t = Student-t statistic
n = number of samples.

For log-normal distributions

where
UCL = upper confidence limit
x = mean of the transformed data
s = standard deviation of the transformed data
H = H-statistic
n = number of samples.

In accordance with EPA guidance (Singh et al. 1997), the non-parametric jackknife method was used to determine the 95 percent UCL for any data that were not identified as either normal or log-normal. The jackknife procedure requires no assumptions regarding the statistical distribution. The procedure is conceptually simple and is based on resampling techniques that tend to require considerable computing power. For a data set of size n, n estimates of the mean are computed by deleting one observation at a time from the data set. The jackknife estimate of the mean and the standard deviation can be calculated to reduce the bias in the data set, and appropriate confidence limits can be derived (see Singh et al. [1997] for mathematical details). For small data sets (those with fewer than 10 samples), the maximum detected concentration is used if the calculated 95 percent UCL exceeds the maximum detected concentration.

The 95 percent UCL was calculated for each of the data sets used as a conservative estimate of the true average concentration for that media that the data set represents. In the case that the calculated 95 percent UCL is greater than the maximum detected concentration, the maximum concentration was used instead of the calculated 95 percent UCL.

For the calculation of both average and 95 percent UCL concentrations, samples with non-detectable levels were considered to contain half of the detection limit of that constituent. In cases where samples with non-detectable levels had detection limits greater than the detected concentrations in all other samples, the data were not used in the calculation of 95 percent UCLs.

Table 3-1 through Table 3-11 present the EPCs for each of the COPCs identified in each medium. These tables include the statistical method used to determine the 95 percent UCL depending on the statistical distribution, if any, that fits the data, the 95 percent UCL and the arithmetic average concentration.

4.3 Quantification of Exposure

Identifying exposure pathways provides a method to estimate doses of contaminants that populations may receive. Each exposure pathway was evaluated for the four elements necessary to indicate potential exposure of a population. Each identified pathway must meet these four criteria:
· a source and mechanism of release of contaminants to the environment
· an environmental transport medium or mechanism of transfer of contaminants among environmental media
· a point of potential contact of humans to the contaminated medium
· an identified route of exposure

An identified pathway indicates that the potential for exposure exists; it does not imply that exposures do or may actually occur. Exposure assessments for current land-use and future land-use scenarios are discussed in the following sections.

4.3.1 Current Conditions

Under current conditions, the potentially exposed populations include on-site trespassers and off-site residents. An on-site trespasser scenario was evaluated because residential properties are adjacent to the eastern boundary of OU V. An older child (aged 7 to 12) trespasser was selected as the sensitive, potentially exposed receptor for the on-site trespasser scenario. A younger child (aged 1 to 6) as a trespasser was not evaluated since the frequency of visits by a child of this age range is very unlikely. Additionally, adults trespassing onto the on-site portions near the Peconic River were considered less likely due to less free time for such activities. The older child could have adequate free time after school hours, on weekends and holidays, and during the summer months. The older child was selected for evaluation based on the greater likelihood and frequency of exposure. An off-site resident was assumed to reside near the off-site upstream section of the Peconic River. Both an adult, a younger child (aged 1 to 6), and an older child (aged 7 to 12) resident were evaluated. Additionally, a recreational hunter/angler may be exposed to contaminants in fish and game. A recreational hunter/angler who was not a riverside resident was evaluated as a potential receptor. In addition, a riverside resident may also be a recreational hunter/angler. This potential receptor was also evaluated. Estimates of the exposures are based on measurements of existing site conditions.

For an older child (aged 7 to 12) as the on-site trespasser, eight exposure pathways are evaluated in this current land use exposure assessment:

· Inhalation of soil particulates and dusts near the Peconic River
· Incidental ingestion of soil near the Peconic River
· Direct dermal contact with soil near the Peconic River
· Incidental ingestion of sediment from the Peconic River
· Direct dermal contact with sediment from the Peconic River
· Inhalation of sediment particulates and dusts from dry areas of the Peconic River
· Incidental ingestion of surface water from the Peconic River
· Direct dermal contact with surface water in the Peconic River

Table 4.1, Table 4.2, and Table 4.3 present the exposure pathway parameters that were used for the exposure algorithms to estimate intake of site-related contaminants through all identified pathways for an older child on-site trespasser for soil, sediment, and surface water, respectively. Some of those parameters (e.g., those not representing standard default exposure values) are discussed below.

Based on an older child (ages 7 to 12) playing and exploring the Peconic River area two days a week for up to eight months a year, the trespasser was assumed to be on-site 64 days a year, as a reasonable maximum exposure (RME). The central tendency exposure (CTE) was assumed to be 13 days/year based on playing and exploring the Peconic River area one day a week during the summer months (i.e., 13 weeks). An inhalation rate of 1.2 cubic meters per hour (m³/hr) was assumed as an average for the entire eight-hour exposure period (EPA, 1997a). This assumed moderate activity levels, on the average, for the entire exposure period.

Potential trespasser exposure to on-site groundwater was evaluated for consideration in this risk assessment. Neither ingestion nor dermal contact to groundwater is possible at OU V under current land-use scenarios. Therefore, trespasser exposure to on-site groundwater was not considered in this risk assessment.

Twelve environmental medium exposure pathways are evaluated in the resident exposure assessment:

· Incidental ingestion of soils from near the Peconic River
· Direct dermal contact with soil from near the Peconic River
· Inhalation of soil particulates and dusts near the Peconic River
· Incidental ingestion of sediment from the Peconic River
· Direct dermal contact with sediment from the Peconic River
· Inhalation of sediment particulates and dusts from dry areas of the Peconic River
· Incidental ingestion of surface water in the Peconic River through recreational activities
· Direct dermal contact with surface water in the Peconic River
· Ingestion of fish caught from the off-site upstream section of the Peconic River
· Ingestion of groundwater as the drinking water source
· Direct dermal contact with groundwater through bathing
· Inhalation of volatiles in groundwater during showering exposure
· External radiation from gamma emitting radionuclides in soil and sediment

Public water hookups have been provided to off-site residents near North Street in the area of groundwater contamination from OU V. However, the risk assessment conservatively assumes that the groundwater may be used as a household and drinking water source in that area.

Table 4.4 through Table 4.18 present the exposure pathway parameters that were used for the exposure algorithms to estimate intake of site-related contaminants through all identified pathways for off-site residents living near the Peconic River. Residents that are recreational anglers and/or recreational hunters that fish and hunt in this area of the Peconic River may also be exposed to contaminants in fish or game at different exposure levels than non-angler residents. The exposure parameters for recreational anglers/hunters are presented in Table 4.19 through Table 4.21 for fish exposure and in Table 4.37 through Table 4.39 for deer exposure. For residents who are recreational anglers/hunters in this area of the Peconic River, both the residential exposure pathways for other media (i.e., soil, surface water, sediment, groundwater) and the recreational angler exposure pathways (i.e., fish) were used together.

Exposure to surface water and sediment from the on-site Peconic River was included in the exposure assessment for the older child trespasser, and exposure to surface water and sediment from the off-site upstream section of the Peconic River was included in the exposure assessment for the off-site resident.

Ingesting chemical contaminants by eating fish caught in the upstream on-site Peconic River was not considered in the current land-use scenario, because on-site fish upstream of North Street are generally too small to be of edible size, and on-site access, excluding the accessible North Street area, is limited for people to actually fish. Ingesting chemical contaminants by eating fish caught off site or on site near North Street was considered in the current land-use scenario for the off-site resident.

As described previously, fish from the on-site Area D near North Street to Schultz Road were considered in the off-site resident exposure. The recreational angler adult and older child (both riverside resident and non-riverside resident) was assumed to have a RME of locally caught fish of 25 grams per day (g/day) (20 pounds per year [lb/year]) and a CTE of eight g/day (6.4 lb/year) (EPA 1997a). The recreational angler younger child was assumed to have a RME of locally caught fish of 12.5 g/day and a CTE of 4.0 g/day. This is based on the assumption that the young child would eat the same number of meals as the adult or older child but would eat smaller portions (4-ounce meals instead of 8-ounce meals). The adult, older child, or younger child riverside resident that is not a recreational angler was assumed to have an RME of 6.5 g/day (5.2 lb/year) (assuming occasional fishing in the area). The 6.5 g/day rate assumed catching and consuming locally caught fish as ten meals of a half pound each or, based on the small size of most fish previously caught in this upstream section of the Peconic River, twenty meals of a quarter pound each. The younger child is assumed to have the same consumption rate as the adult or older child because of the potential smaller size of the meals already assumed as possible for the adult and older child. Because the majority of the general population does not consume locally caught fish (EPA 1997a), it was assumed that CTE factors would not include exposure to locally caught fish. Fish exposure frequency was 365 days per year and the exposure duration for adults was 30 years for RME and nine years for CTE and for children was 6 years for both RME and CTE.

Data on concentrations of contaminants in deer meat from the Peconic River area are limited to radiological analysis. Therefore, the rates of consumption of deer for the recreational angler/hunter were only applicable to the radiological risk assessment. The recreational hunter (both riverside resident and non-riverside resident) was assumed to have an RME of 28.9 kilograms per year (kg/year) (64 lb/year) and a CTE of 2.7 kg/year (6 lb/year) (EPA 1997a). The riverside resident that is not a recreational hunter, or is not within a family with a recreational hunter, was assumed to eat no locally caught deer. Deer exposure frequency was assumed to be 365 days per year and the exposure duration was 30 years for RME and 9 years for CTE.

4.3.2 Future Conditions

A residential scenario was addressed for future land-use of the on-site Peconic River area in the event that the area is ever developed as residential property. A residential adult, a young child (aged 1 to 6) as the most sensitive receptor, and an older child (aged 7 to 12) were used as the potentially exposed populations.

Typical residential exposures to environmental media were evaluated for both adults and a small child, aged 1 to 6, in the hypothetical future land use scenario. This conservative exposure scenario assumed that residents would live on site near the Peconic River for up to 30 years, and that residents would use on-site groundwater for all domestic water needs. This residential exposure assessment also included exposure to surface water and sediment through play and recreational activities. For this exposure assessment of a hypothetical on-site resident, a total of thirteen exposure pathways were evaluated for the adult and child residents.

The exposure pathway parameters used in exposure algorithms to estimate intake of site-related contaminants through all identified pathways for adult and young child residents are listed in Table 4.22 through Table 4.36. Future on-site residents that are recreational anglers and/or recreational hunters that fish and hunt in this area of the Peconic River may also be exposed to contaminants in fish or game at different exposure levels than non-angler residents. For residents who are recreational anglers/hunters in this area of the Peconic River, both the residential exposure pathways for other media (i.e., soil, surface water, sediment, groundwater) and the recreational angler exposure pathways (i.e., fish) were used together. Residents were assumed to be exposed to soil and groundwater-related contaminants by their respective pathways up to 350 days per year. Exposure to sediment and surface water through play and recreational activities was assumed to occur 150 days a year as a reasonable maximum exposure for the young child and older child living adjacent to the upstream section of the Peconic River. This was based on the assumption that the available days for such activities is generally during the non-winter months (length of day light and warmer weather) and that half of these available days are spent outdoors playing in the sediment of the Peconic River. The days of non-exposure could be due to weather conditions, playing outdoors but elsewhere, not having available free time during day light hours, spending free time indoors (e.g., watching television, playing with computer or video games). The 150 days of exposure additionally assumed that half of the winter weekend days were spent playing in the sediment of the Peconic River. The following equation provides the calculation of the exposure frequency.

Exposure to surface water and sediment from the Peconic River was included in the future on-site residential exposure scenario. The on-site groundwater data set was used to estimate potential exposure to future on-site residents by three pathways: ingestion of water for drinking and cooking, dermal absorption of contaminants in groundwater through bathing, and inhalation of volatile organic contaminants during showering.

4.4 Exposure Equations and Parameters

Environmental medium-specific exposure algorithms were developed for each of the identified exposure route/pathways. Exposure algorithms are used to estimate chronic daily intake of non-radiological COPCs by receptors (e.g., industrial workers, adult and young child residents) in potentially exposed populations. The exposure to radiological COPCs is assessed using basically the same algorithms and assumptions. The differences between estimating non-radiological and radiological exposure are described in Section 4.4.12.

For each exposure activity, the chronic daily intake (CDI), expressed as mg/kg-day, was an averaged daily dose of a COPC ingested or absorbed by a receptor. The averaged dose received by a receptor was the critical point estimate for determining the extent of health risk/hazard associated with exposure to each constituent. Determining the exposure assessment was difficult to establish and accounts for much of the inherent uncertainty associated with exposure assessment.

In general, three parameters most influence the CDI:

· COPC concentration in the exposure medium
· COPC dose received during each exposure activity event
· Lifetime frequency of exposure activity events

Point estimates of COPC concentrations do not vary in assessing the CDI by different exposure routes to the same medium. However, exposure parameters that influence receptor intake or absorption of COPCs, such as exposure duration and frequency, can and do vary in the exposure algorithms used to estimate the CDI by different exposure routes to the same medium. For each identified pathway, a RME scenario was developed. The exposure parameters used in the RME assessments are both average and upper-bound (90^th to 95^th percentile distribution) point estimates for each parameter and together should represent maximum exposures that can reasonably be expected.

4.4.1 Inhalation of Airborne Dusts and Particulates

Potential health hazards posed by airborne particulate material emanating from the Peconic River site was estimated by using a respirable particle concentration based on the upper bound 95^thpercentile concentration for airborne particulates in Suffolk County. Based on a study of 20 locations in Suffolk County, the average outdoor respirable particulate load was 21.8±4.5 micrograms per cubic meter (m g/m³) with an upper bound 95^th percentile concentration of 30.8 m g/m³ (EPA 1995). This concentration of airborne particulate material is a conservative estimate for site-related airborne dusts and particulates. Studies have indicated that only a fraction of the measured particulates in air are derived from on-site soil (NJDEP 1995). In fact, EPA’s soil screening guidance (EPA, 1996b) recommends using a particulate emission factor of 1.32´ 10⁹ m³/kg which is equivalent to a concentration of airborne particulate material of only 0.76 m g/m³.

A primary assumption of the model was that all airborne dusts and particulates emanating from surface soil have aerodynamic average diameters less than 30 microns and are considered respirable particulates. The particulate concentration of 30.8 m g/m³ was used to estimate the constituent-specific concentrations of site-related contaminants, by multiplying this particulate concentration by the fraction of the constituent concentration in soil or dry Peconic River sediment.

For example, the 95^th percentile upper confidence limit of the average concentration of arsenic in off-site sediment of the Peconic River is 5.39 mg/kg. Therefore, the concentration of arsenic in airborne particulate material when the river is dry and the sediment exposed was estimated as 30.8 m g/m³ ´ 0.00000539 = 0.000166 m g/m³.

Because volatile organic compounds were not determined to be COPCs in soils and sediment at the Peconic River, inhalation of volatile organics from soil or sediment was not considered in the inhalation pathways.

Sediment is less likely to contribute airborne dusts/particulates since it is submerged below the water surface. However, there are parts of the Peconic River that are intermittent (i.e., sometimes wet and sometimes dry), and fugitive dusts may be generated during the dry periods. Sediment in Area D and the off-site upstream section down to the northern tributary to the Peconic River is considered to be intermittent and to contribute to airborne dusts and particulates for half of the year.

Inhalation rates vary with activity level and with age. Inhalation rates are lowest when at rest or sedentary and increase with the level of exercise. EPA (1991) recommended the use of an inhalation rate of 20 cubic meters per day (m³/day) for RME evaluations for adults in residential settings. For resident children, the long-term average inhalation rate of 8.7 m³/day (EPA 1989a) was assumed. Trespasser inhalation rates were based on assumed activity patterns. Because an eight-hour exposure period was considered for each exposure event, it was assumed that the exposure would consist of a mix of light, moderate, and heavy activity. It was assumed that the average inhalation rate over the entire eight-hour exposure period was that of moderate activity 1.2 m³/hr. Inhalation rates for CTE evaluations were assumed to be the same as for RME evaluations.

Inhalation dose estimates of non-radiological airborne contaminants (radiological contaminants are addressed in Section 4.4.12) were calculated by the following algorithm:

where:
CDI = chronic daily intake via inhalation (mg/kg-day)
CA = constituent concentration in air (µg/m³)
ABS = absorption factor (1.0, unitless)
IR = inhalation rate (m³/hr)
ET = exposure time (hr/day)
EF = exposure frequency (days/yr)
ED = exposure duration (years)
CF = conversion factor (1.0 x 10^-3 mg/µg)
BW = body weight (kg)
AT = averaging time (days)

In the current land-use scenarios, an older child trespasser was assumed to be on site for 64 days per year for RME and 13 days per year for CTE when exposures to airborne dust and particulates near the Peconic River could occur. Future land-use resident inhalation exposure and current land-use off-site resident inhalation exposure algorithms assume that residents would be exposed to airborne COPCs from near the Peconic River 24 hours per day, 350 days per year. Adults would be exposed for 30 years in the RME exposure scenario and for 9 years in the CTE scenario, whereas children would be exposed for 6 years in both the RME and CTE exposure scenario.

4.4.2 Incidental Ingestion of Soil

The CDI of non-radiological contaminants in soil from near the Peconic River due to incidental ingestion was calculated by the following formula:

where:
CDI = chronic daily intake via ingestion (mg/kg-day)
CS = constituent concentration in soil (mg/kg)
ABS = absorption factor (1.0, unitless)
IR = ingestion rate (mg/day)
EF = exposure frequency (days/yr)
ED = exposure duration (years)
CF = conversion factor (1.0 x 10^-6 kg/mg)
BW = body weight (kg)
AT = averaging time (days)

Incidental ingestion of soil occurs during normal activities and is more frequent with children. The most frequent activity resulting in soil ingestion is through the transfer of dirt on the hands to the mouth. Thus, activities leading to soil on the hands can lead to ingestion of soil. Digging in the soils or sediment is the most obvious route for such exposure, though there are indirect routes also such as catching wildlife in the water (e.g., frogs, fish, turtles), gathering vegetation from the river bed, gathering sticks or logs from the river bed, and petting or holding an animal (e.g., family dog) that may have traveled in the river or exposed sediment. Outdoor activities in good weather promote the ingestion of soil. Studies have been conducted (Davis et al. 1990; Calabrese et al. 1989; Stanek and Calabrese 1995a, b; Van Wijnen et al. 1990) that were used to evaluate incidental soil ingestion rates (EPA 1997a). These studies measured soil ingestion by children and adults at varying levels of potential exposure. Studies were conducted in a campground setting that may have incorporated many of the indirect and high levels of exposures, though the studies do not differentiate between different routes of soil/sediment ingestion. These studies also do not differentiate between soils and sediment, but implicitly consider them to be the same. Thus, when using soil ingestion rates for both soil and sediment (see Section 4.2.8), the total ingestion rate is essentially extra-conservative. EPA (1997a) recommends a mean soil ingestion rate of 100 mg/day for children under 6 years of age (CTE), with the use of 200 mg/day as a conservative estimate of the mean (RME) (EPA 1991). An ingestion rate of 100 mg/day for adults (RME) is recommended (EPA 1991) for residential and agricultural settings; the CTE assumption is 50 mg/day (EPA 1997a). For this human health risk assessment, the older child trespasser was assumed to ingest 100 mg soil per day when on site. For the hypothetical residential scenario, adults and young children are assumed to ingest 100 mg and 200 mg soil, respectively, for RME scenarios and 50 mg and 100 mg of soil, respectively, for CTE exposures, on a daily basis, 350 days per year.

4.4.3 Dermal Contact with Soil

The CDI of non-radiological contaminants in surface soil through dermal absorption as a result of direct contact with surface soil from near the Peconic River was calculated by the following formula:

where:
CDI = chronic intake from dermal contact with soils (mg/kg-day)
CS = constituent concentration in soil (mg/kg)
ABS = absorption factor (chemical specific)
SA = surface area of exposed skin; (cm²/event)
AF = soil-to-skin adherence factor (milligrams per square centimeter [mg/cm²])
EF = exposure frequency (events/yr)
ED = exposure duration (years)
CF = conversion factor (1.0 x 10^-6 kg/mg)
BW = body weight (kg)
AT = averaging time (days).

Though the dermal uptake route of exposure may be important for many organic chemicals, dermal uptake is generally not an important route of uptake for radionuclides, which have small permeability constants (EPA, 1989a). Dermal uptake of radionuclides is not evaluated in this risk assessment.

For chemical contaminants, it was assumed that the hands, forearms, lower legs, and head come into direct contact with soil/dust (EPA 2001). Recommended exposed skin surface area is 5,700 square centimeters (cm²) for adults, 2,800 cm² for young children. An exposed skin surface area for an older child was assumed to be 4,600 cm² based on age-specific surface area data (EPA 2001). An adherence factor of 0.2 mg/cm² was assumed for RME and 0.04 mg/cm² for CTE (EPA 2001).

Dermal contact exposure to soil was assumed to occur 64 times per year for a trespasser for RME and 13 times per year for CTE. In accordance with EPA guidance, the frequency of direct dermal soil exposure in the future residential exposure scenarios was assumed to be a conservative estimate of 350 events per year for both the adult and child receptors.

4.4.4 Ingestion of Groundwater

Use of residential well water as the sole water supply for all domestic needs was a principal assumption underlying the future land-use residential exposure scenario on the BNL site, though this is considered to be highly unlikely. Current off-site residents living along the Peconic River in the upstream section have been provided connection to the public water supply. However, the groundwater in the area is classified as Class GA (fresh groundwaters) by the NYSDEC (6 New York Codes, Rules, and Regulations [NYCRR] Part 701), and there may be a potential for exposure to well water; therefore, the use of well water as the sole water supply for all domestic needs was also assumed for the off-site resident. The CDI of non-radiological COPCs in groundwater (radiological COPCs are addressed in Section 4.4.12) due to ingestion is calculated by the following formula:

where:
CDI = chronic daily intake of contaminants in groundwater (mg/kg-day)
CW = constituent concentration in groundwater (mg/L)
IR = ingestion rate (L/day)
ABS = absorption factor (1, unitless)
EF = exposure frequency (days/year)
ED = exposure duration (years)
BW = body weight (kg)
AT = averaging time (days)

The ingestion rate for drinking water was assumed to be 2 liters per day (L/day) and 1.4 L/day for adults for RME and CTE and 1.3 L/day and 0.74 L/day for children for RME and CTE (EPA 1997a). Use of groundwater as a drinking water source by adults was assumed to occur 350 days for either 30 years (RME) or 9 years (CTE). Exposure duration for children is 6 years.

4.4.5 Dermal Contact With Groundwater

The CDI of contaminants in on-site groundwater due to dermal absorption while bathing was calculated by the following formula:

where:
CDI = chronic daily intake by dermal contact with groundwater (mg/kg-day)
DA_event = Absorbed dose per event (mg/cm²-event) – this is a function of several chemical specific parameters and equations presented in EPA (2001)
SA = surface area of exposed skin (cm²)
EV = event frequency (events/day)
t_event = event duration (hours/event)
EF = exposure frequency (days/yr)
ED = exposure duration (years)
CF = conversion factor (1.0 x 10^-3 L/cm³)
BW = body weight (kg)
AT = averaging time (days)

For chemical contaminants, the dermal contact route/pathway accounts for daily exposure to water while bathing. Total body surface area (18,000 cm² for adults, 11,300 cm² for older child, and 6,600 cm² for young child) was assumed in this scenario and bathing time was assumed to be 0.58 hours for adults and older children and 1 hour for young children per event for RME exposure and 0.25 hours for adults and older children and 0.33 hours for young children for CTE exposure (EPA 2001).

4.4.6 Inhalation of Groundwater

Inhalation of volatile organic compounds in ground water used during shower was assumed to occur for the riverside residents in both the current scenario and the hypothetical future on-site residential scenario. Radionuclides are generally not volatile and inhalation of ground water is not considered a significant exposure route. The following formula was used to calculate the non-radiological CDI of volatile organic contaminants in ground water due to inhalation during showering:

where:
IR_air = inhalation rate of air (m³/hr)
EV = event frequency (events/day)
t_event = event duration including time during shower and immediately after shower (hours/event)
EF = exposure frequency (days/year)
ED = exposure duration (years)
BW = body weight (kg)
AT = averaging time (days)
C_air = chemical concentration in air (mg/m³) derived from the following equation from Schaum et al. (1994)

where:
C_water = chemical concentration in water (mg/L)
K = volatilization factor (unitless)
F_water = water flow rate (L/hour)
V = volume of bathroom (m³)
t₁ = time of shower (hours/event)
t₂ = time immediately after shower (hours/event)
t_event = t₁ + t₂ (hours/event)

The inhalation rate for adults and children during showering was assumed to be 0.6 m³/hr and 0.36 m³/hr, respectively (EPA 1989a). Showering time was assumed to be 12 minutes (0.2 hours) for RME and 7 minutes (0.12 hours) for CTE (Schaum et al. 1994). Time spent in the bathroom after the shower is turned off is assumed to be 30 minutes (0.5 hours) for RME and 10 minutes for CTE (0.2 hours). Recommended values for flow rate of 750 L/hour, volume of bathroom of 11 m³, and volatilization factor of 0.5 are used (Schaum et al. 1994). It was assumed that residents shower once per day for 350 days per year.

4.4.7 Incidental Ingestion of Surface Water

Incidental ingestion of surface water was assumed to occur for the older child in the trespasser scenario and for both the adult and young child in the hypothetical future residential scenario through play and recreational activities. The following formula was used to calculate the CDI of non-radiological contaminants in surface water (radiological contaminants are addressed in Section 4.4.12) due to incidental ingestion:

where:
CDI = chronic daily intake of contaminants in surface water (mg/kg-day)
C_sw = constituent concentration in surface water (mg/L)
IR = ingestion rate (L/event)
ABS = absorption factor (1.0, unitless)
EF = exposure frequency (events/year)
ED = exposure duration (years)
BW = body weight (kg)
AT = averaging time (days)

The trespasser was assumed to have an RME frequency of visits to the site of 64 days/year and a CTE frequency of 13 visits/year. Since only half of the on-site portion of the Peconic River contains water year round, exposure frequency was assumed to be the same. However, recent flow data and observations suggest that off-site areas also contain water less than half of the year. The data from 1996 to 2002 indicate that the river has not flowed over the HQ gauging station from more than 50 percent of the time. At the current time (mid-November 2002), there has been no flow in the upstream off-site area of the Peconic River since January 2002. Thus, though riverside child residents were assumed to visit the Peconic River and be exposed to sediment 150 days per year as an RME and 50 days per year as a CTE, they were assumed to be exposed to surface water only half of that time. Resident adult scenarios assumed an RME exposure frequency at the Peconic River of 64 events per year (twice a week for 8 months of the year) and a CTE exposure frequency of 13 events per year (once per summer week). Exposure to surface water was assumed to occur only half of that time. Incidental ingestion of surface water during recreational activities was estimated at an ingestion rate of 50 ml per hour (EPA 1989a), during an exposure period of 2.6 hours per event, for a total of 0.13 liters (L) surface water ingested per event. These ingestion rates were derived from swimming activities and were considered to be very conservative estimates of ingestion rates for activities that may occur at the Peconic River such as fishing, wading, or hiking.

4.4.8 Dermal Contact with Surface Water

Dermal contact with surface water was assumed to occur for the older child in the trespasser scenario and for the adult and young child in the hypothetical future residential scenario through play and recreational activities.

The same algorithm that was used for dermal contact with groundwater was used to estimate dermal exposure to surface water. Though the dermal uptake route of exposure may be important for many organic chemicals, dermal uptake is generally not an important route of uptake for radionuclides, which have small permeability constants. Additionally, the shielding effects of water also reduce potential exposure (EPA, 1989a). Dermal uptake of radionuclides is not evaluated in this risk assessment.

The trespasser scenario assumed an RME frequency of visits to the site at 64 days/year and a CTE frequency of 13 visits/year. Since about half of the Peconic River on the site contains water year round, exposure frequency was assumed to be the same. However, recent flow data and observations suggest that off-site areas contain water less than half of the year. Thus, though riverside child residents were assumed to visit the Peconic River and be exposed to sediment 150 days per year as an RME and 50 days per year as a CTE, they were assumed to be exposed to surface water only half of that time. Resident adult scenarios assumed an RME exposure frequency at the Peconic River of 64 events per year (twice a week for 8 months of the year) and a CTE exposure frequency of 13 events per year (once per summer week). Exposure to surface water was assumed to occur only half of that time. The same exposure frequency and exposure time was used for surface water ingestion.

Total body surface area (18,000 cm² for adults, 11,300 cm² for older child, and 6,600 cm² for young child) was assumed in this scenario and bathing time was assumed to be 0.58 hours for adults and older children and 1 hour for young children per event for RME exposure and 0.25 hours for adults and older children and 0.33 hours for young children for CTE exposure (EPA 2001).

4.4.9 Incidental Ingestion of Sediment

The CDI of non-radiological contaminants (radiological contaminants are addressed in Section 4.4.12) due to incidental ingestion of sediment while wading or playing in the Peconic River on-site at was calculated by the following formula:

where:
CDI = chronic daily intake of contaminants from sediment (mg/kg-day)
C_sed = constituent concentration in sediment (mg/kg)
IR = ingestion rate (mg/event)
CF = conversion factor (1.0 x 10^-6 kg/mg)
ABS = absorption factor (1, unitless)
EF = exposure frequency (events/year)
ED = exposure duration (years)
BW = body weight (kg)
AT = averaging time (days)

An RME frequency of 64 events per year was assumed for the on-site trespasser as well as a CTE exposure of 13 events per year. The riverside resident child was assumed to play at the river 150 days per year as an RME and 50 days per year as a CTE. The riverside adult resident was assumed to engage in activities in the river 64 events per year as an RME and 13 events per year as a CTE. Incidental ingestion of sediment during these play activities was assumed to be 100 mg per event for an adult and the older child trespasser and 200 mg per event for a young child as an RME and 50 mg/event and 100 mg/event as a CTE, respectively. As mentioned earlier, the ingestion of sediment was considered in addition to the ingestion of soil. Thus, the total soil and sediment ingestion rates are very conservative estimates.

4.4.10 Dermal Contact with Sediment

The CDI of non-radiological contaminants in sediment through dermal absorption as a result of direct contact with sediment was calculated through the same formula as that for dermal absorption as a result of direct contact with soil.

where:
CDI = chronic intake from dermal contact with sediment (mg/kg-day)
CS = constituent concentration in sediment (mg/kg)
ABS = absorption factor (chemical specific)
SA = surface area of exposed skin; (cm²/event)
AF = soil-to-skin adherence factor (mg/cm²)
EF = exposure frequency (events/yr)
ED = exposure duration (years)
CF = conversion factor (1.0 x 10^-6 kg/mg)
BW = body weight (kg)
AT = averaging time (days).

For chemical contaminants, it is assumed that the hands, forearms, lower legs, and head come into direct contact with sediment (EPA 2001). Recommended exposed skin surface area is 5,700 cm² for adults, 2,800 cm² for young children. An exposed skin surface area for an older child is assumed to be 4,600 cm² based on age-specific surface area data (EPA 2001). An adherence factor of 0.07 mg/cm² is assumed for RME and 0.01 mg/cm² for CTE (EPA 2001).

An RME frequency of 64 events per year was assumed for the on-site trespasser as well as a CTE exposure of 13 events per year. The riverside resident child was assumed to play at the river 150 days per year as an RME and 50 days per year as a CTE. The riverside adult resident was assumed to engage in activities in the river 64 events per year as an RME and 13 events per year as a CTE. Exposure assumptions for dermal uptake of COPCs in sediment are comparable to and have uncertainties similar to the soil dermal contact exposure algorithm. It was assumed that the hands, forearms, lower legs, and head come into direct contact with soil/dust (EPA 2001). Recommended exposed skin surface area is 5,700 cm² for adults, 2,800 cm² for young children. An exposed skin surface area for an older child was assumed to be 4,600 cm² based on age-specific surface area data (EPA 2001). An adherence factor of 0.07 mg/cm² is assumed for RME and 0.01 mg/cm² for CTE (EPA 2001). The same dermal absorption factors and default values used in soil dermal exposure were used in these recreational exposure scenarios.

4.4.11 Ingestion of Locally Caught Fish

The CDI of non-radiological contaminants in fish (radiological contaminants are addressed in Section 4.4.12) caught locally from the Peconic River (i.e., fish caught on site for the future on-site resident scenario, and fish caught from the off-site upstream section of the Peconic River for the off-site resident scenario) was calculated by the following formula:

where:
CDI = chronic intake from consumption of locally caught fish (mg/kg-day)
C_fish = constituent concentration in fish (mg/kg)
IR = ingestion rate (kg/day)
EF = exposure frequency (days/yr)
ED = exposure duration (years)
BW = body weight (kg)
AT = averaging time (days)

The recreational angler/hunter was assumed to have the greatest exposure to contaminants in fish tissue and/or deer tissue. Analytical data on deer tissue concentrations of contaminants does not contain information on non-radiological contaminants. Thus, the exposure to non-radiological contaminants in deer meat cannot be quantitatively addressed in this risk assessment. The exposure to radiological contaminants in deer meat is addressed in Section 4.4.12.

The RME fish ingestion rate for the recreational angler/hunter was assumed to be 25 g/day (20 lb/year) and the CTE was assumed to be 8 g/day (6.4 lb/year). The riverside resident that is not a recreational angler/hunter may consume some locally caught fish. An ingestion rate of 6.5 grams per day (5.2 lb/year) was used as an RME for the on-site areas and for the off-site upstream areas. Much of these areas are considered unfishable and they support a limited fish population of edible size fish. Almost all of the fish captured from these areas of the Peconic River as part of the RI and the BNL annual monitoring had whole body weights less than a half pound (0.23 kg) and most were less than a quarter pound (0.113 kg); they would not be considered of edible size. In particular, fish collected from on-site upstream of North Street were much smaller, though some fish collected off-site or on-site at North Street were of edible size. EPA (1989a) provides a 50^th percentile fish meal size of a quarter pound (0.113 kg) and a conservative estimate of the average fish meal size of half pound (0.227 kg). An average daily consumption rate of 6.5 g/day is equivalent to having 20 quarter-pound meals of fish during a year that are caught from the on-site or off-site upstream section of the Peconic River. Given the small size of fish and the small fish population size, the use of the 6.5 g/day ingestion rate is conservative for the general riverside resident population. The majority of the population does not consume locally caught fish. Thus, it was assumed that the riverside resident that is not a recreational hunter/angler does not consume locally caught fish as a CTE exposure.

4.4.12 Radionuclide Exposure

Exposure to radionuclides may occur through the same pathways described in the preceding sections. Additionally, exposure via external gamma radiation from radionuclides in soil and sediment represents an additional source. Radionuclide exposure and risk assessment was addressed in the Plutonium Contamination Characterization and Radiological Dose and Risk Assessment Report (IT 2000). That report identified cesium-137 as the greatest contributor to the total radiological dose. Since that report, additional sediment samples have been collected from the on-site and off-site upstream section of the Peconic River. These were analyzed for cesium-137 as well as inorganic and organic compounds. The radiological dose and risk was re-assessed based on the revised exposure concentrations for cesium-137 as well as the other radionuclides determined to be COPCs. In general, exposure pathways and parameters used previously (IT 2000) are used in this risk assessment.

EPA (1989a, 1991b) present methods for estimating risk to human health for radionuclide exposure. They recommend the use of appropriate computer models and the use of site-specific information to refine the risk assessments. One appropriate computer model that can be used is the RESRAD (RESidual RADiation) Model. RESRAD is a computer code developed by Argonne National Laboratory that calculates radiation dose and excess lifetime cancer risk. Some of the pathway exposures and resulting dose and risk assessments in this risk assessment were determined using a computer model RESRAD (i.e., external gamma radiation, airborne particulate inhalation); these require additional parameters or assumptions not incorporated in the chemical risk assessment. The RESRAD program uses transport models to estimate concentrations in fish, meat (e.g., deer), groundwater, and other media based on initial soil concentrations. For all other pathways (e.g., ground water ingestion, deer and fish consumption), actual concentrations were measured at the potential exposure points (fish, deer meat, surface water, groundwater). The use of actual concentrations as opposed to modeled concentrations provides a more realistic assessment of radiological dose and risk. Thus, the exposures through these other pathways are determined using virtually the same equations as are used for the chemical risk assessment; parameters for these pathways were exactly the same as those for the chemical risk assessment. The following discussion presents a discussion of the potential receptors to be addressed and the exposure assumptions and pathways to be used.

Receptors
The radionuclide risk assessment addresses the same potential receptors that the chemical risk assessment does. However, unlike chemical cancer risks, risks due to radionuclide exposure are not body-weight dependent, and unlike chemical non-cancer health hazards, radionuclide exposure is not averaged over the exposure period. Thus, exposure factors that have a great degree of significance in chemical risk assessment and necessitate the evaluation of adults, older children, and younger children separately, are not as important in the radiological risk assessment. Regardless, the adult, younger child, and older child are each evaluated independently. Both current and future receptors are addressed:

The current receptor scenarios include the following:
· Off-site riverside resident
· Off-site riverside resident recreational angler and hunter
· Off-site recreational angler and hunter
· On-site trespasser (older child only)

The future receptor scenarios include the following:
· Future on-site riverside resident
· Future on-site riverside resident recreational angler and hunter
· Future on-site recreational angler and hunter

Exposure Pathways
The exposure pathways addressed in the radionuclide risk assessment are discussed individually in the following paragraphs and are the following:
· Locally caught fish consumption
· Locally caught deer consumption
· Incidental surface water ingestion
· Ground water ingestion
· Incidental sediment ingestion
· Incidental soil ingestion
· Inhalation of airborne particulates
· External gamma radiation

As discussed previously, dermal uptake of radionuclides, which have small permeability constants, is generally not an important route of uptake for radionuclides (EPA, 1989a). Dermal uptake of radionuclides is not evaluated in this risk assessment. Likewise, radionuclides are generally not volatile and inhalation of ground water is not considered a significant exposure route.

The exposure to radionuclides is assessed using the same equations presented in the previous sections for chemical contaminants, except that the body weight and averaging time terms are omitted. The result of these calculations is an estimate of intake expressed in terms of activity (e.g., pCi) instead of a body weight normalized chronic daily intake (e.g., mg/kg-day). In addition, the endpoint of a radiation exposure assessment is usually expressed in terms of the annual radiation dose, which is calculated by multiplying the annual intake by the appropriate dose conversion factors. The equations for estimating radiation dose are presented below. The equations for calculating lifetime intake of radionuclides is simply the annual intake multiplied by the exposure duration.

Locally Caught Fish Consumption
Fish consumption rates for the radionuclide risk assessment, as well as the other exposure parameters, were the same as those for the non-radiological risk assessment. The radiation dose from fish consumption was calculated by the following formula:

where:
Dose = annual radiation dose from consumption of locally caught fish (millirem per year [mrem/year])
C_fish = constituent concentration in fish (pCi/g)
IR = ingestion rate (g/day)
EF = exposure frequency (days/yr)
CF = dose conversion factor (mrem/pCi)

Locally Caught Deer Consumption
Deer consumption rates for the radionuclide risk assessment were described previously. The recreational hunter adult and older child (both riverside resident and non-riverside resident) was assumed to have an RME of 28.9 kg/year (64 lb/year) and a CTE of 2.7 kg/year (6 lb/year) (EPA 1997a). The recreation hunter younger child (or younger child member of recreation hunter family) was assumed to consume deer meat meals at the same frequency but at half the meal size. Thus, consumption rates for the younger child were assumed to be 14.45 kg/year (32 lb/year) for RME and 1.35 kg/year (3 lb/year) for CTE. The riverside resident that is not a recreational hunter, or is not within a family with a recreational hunter, was assumed to eat no locally caught deer. Exposure duration was 30 years for RME and 9 years for CTE for the adult and 6 years for both RME and CTE for the older and younger child.

The radiation dose from deer meat consumption was calculated by the following formula:

where:
Dose = annual radiation dose from consumption of locally caught fish (mrem/year)
C_deer = constituent concentration in deer (pCi/g)
IR = ingestion rate (kg/year ´ 1000 g/kg)
CF = dose conversion factor (mrem/pCi)

Incidental Ingestion of Sediment
Incidental ingestion rates for sediment, as well as the other exposure parameters, in the radionuclide risk assessment were the same as those for the non-radiological risk assessment. The radiation dose from incidental ingestion of sediment was calculated by the following equation:

where:
Dose = annual radiation dose from ingestion of sediment (mrem/year)
C_sed = constituent concentration in sediment (pCi/g)
IR = ingestion rate (mg/event ´ 0.001 g/mg)
EF = exposure frequency (events/year)
CF = dose conversion factor (mrem/pCi)

Incidental Ingestion of Surface Water
Incidental ingestion rates for surface water, as well as the other exposure parameters, in the radionuclide risk assessment were the same as those for the non-radiological risk assessment. The annual radiation dose from ingestion of surface water was calculated using the following equation:

where:
Dose = annual radiation dose from ingestion of surface water (mrem/year)
C_sw = constituent concentration in surface water (pCi/L)
IR = ingestion rate (L/event)
EF = exposure frequency (events/year)
CF = dose conversion factor (mrem/pCi)

Incidental Ingestion of Soil
Incidental ingestion rates for soil, as well as the other exposure parameters, in the radionuclide risk assessment were the same as those for the non-radiological risk assessment. The annual radiation dose from incidental ingestion of soil was calculated from the following equation:

where:
Dose = annual radiation dose from ingestion of sediment (mrem/year)
C_soil = constituent concentration in soil (pCi/g)
IR = ingestion rate (mg/event ´ 0.001 g/mg)
EF = exposure frequency (events/year)
CF = dose conversion factor (mrem/pCi)

Groundwater Ingestion
The consumption rates for groundwater used as a drinking water source, as well as the other exposure parameters, were the same in the radionuclide risk assessment as in the chemical risk assessment. The annual radiation dose from consumption of ground water was calculated from the following equation:

where:
Dose = annual radiation dose from consumption of groundwater (mrem/year)
C_water = constituent concentration in groundwater (mg/L)
IR = ingestion rate (L/day)
EF = exposure frequency (days/year)
CF = radiation dose conversion factor (mrem/pCi)

External Gamma Radiation and Inhalation of Airborne Particulates
Both the external gamma radiation and inhalation of airborne soil and sediment particulates pathways were modeled through the RESRAD computer program. The inhalation rate was the same as that used for the chemical risk assessment: 20 m³/day or 7,200 m³/year (EPA 1997a). The exposure frequency for inhalation and external gamma radiation was 350 days a year. This time is divided between indoor, outdoor, and at-river exposures. It was assumed that, on average, half of each day was spent indoors at the home, one quarter of each day was spent outdoors, and one quarter of each day was spent away from the home. This was consistent with the previous radionuclide risk assessment.

As mentioned previously, 150 days were spent in activities directly at the river. It was assumed that the total six hours of outdoor time for the 150 days at the river are spent at the river. The remaining 200 days, the outdoor time was spent outdoors at home. Since the river is intermittent, it was assumed that half of each exposure pathway was during dry conditions and half was during wet conditions; this was also consistent with the previous radiological risk assessment.

The previous risk assessment treated the entire off-site section of the river from BNL boundary to Schultz Road as the source area. In response to comments received regarding generally higher levels of contaminants expected in Area D where homes actually exist, the sediment source area for this radiological risk assessment is the Area D off-site section of the Peconic River and the soil source area is the soils adjacent to the Peconic River in Area D.

Two factors that are important related to the Peconic River sediment exposures are related to the source "shape" factors. These include the distance to the source, and the size and shape of the source. When engaged in activities at the Peconic River, the distance to the sediment source was considered to be zero meters. Houses are not situated directly on the river but are some distance away from the river. Measurements made from the river edge to the nearest resident near the BNL site showed this distance to be 19.5 meters. To remain conservative in the risk assessment, the distance to the house was assumed to be 10 meters from the sediment source area (i.e., the Peconic River sediment). At the same time the distance to soils alongside the river is less than the distance to sediment. Though the potentially contaminated soils represent those soils near the river and are still at some distance from the houses, for the purposes of exposure via inhalation and external gamma radiation, the distance from the soil source area was conservatively assumed to be zero meters in the absence of site-specific data. A survey of the cesium-137 activity between the high water mark of the Peconic River and the off-site residences in Area D found that cesium-137 activities in soils nearer to the residences were less than one pCi/g. Thus, the distance to sediment of 10 meters and distance to contaminated soils of zero meters are considered to be conservative assumptions.

Another factor in determining the dose obtained from a source is the size and shape of the source area. The Peconic River has an irregular shape throughout the area near BNL, and at each point along the river, the shape is quite different. The essential elements of the selected shape for the RESRAD model is that all segments of the river could be contained within the selected shape at each of the points along the length of the Peconic River in Area D with the shape being located 10 meters from the assumed house position. The shape parameter of the sediment source area used for external gamma radiation and inhalation exposure was conservatively based on a rectangular source area of 100 meters across and 500 meters long, giving a total area of 50,000 m², with residences located adjacent to the river and houses 10 meters from the river.

All other RESRAD input parameters used in the external gamma and inhalation pathways were the same as used previously. The RESRAD parameters are summarized in the Table 4.37, with those parameters that have been changed from earlier risk assessments as indicated in the above paragraph. Since there are two source areas, and residents may be exposed to either when at the house or playing at the river, it was necessary to make dose and risk calculations from the RESRAD model for each applicable condition and then add these results together to arrive at a total dose or risk calculation from the inhalation or external gamma pathway. The following conditions require individual model calculations for the inhalation and external gamma pathways:

· Exposure from soils while at the house
· Exposure from sediment while at the house when the river is dry
· Exposure from sediment while playing at the river when the river is dry
· Exposure from exposed sediment while at the house when the river is mostly wet
· Exposure from exposed sediment while playing at the river when the river is mostly wet

5.0 Toxicity Assessment

The toxicity assessment evaluates the potential for the COPCs to cause adverse health effects in exposed individuals, and establishes a relationship between exposure to a constituent and the increased likelihood and severity of induced adverse health effects.

Two broad categories of chemically-induced disease states — cancer and non-cancer causing health effects — were evaluated in the toxicity assessment for each identified COPC for the Peconic River area. In the same way that an exposure assessment attempts to define the chronic lifetime dosage of COPCs received by an individual in a given scenario, the toxicity assessment links adverse effects associated with exposure to the particular COPC. Establishing an association between exposure to a constituent and the possible adverse effects is the goal of toxicology. The dose received determines the magnitude of any anticipated adverse effects related to the constituent's inherent toxicity.

Toxicity values are used in risk characterization to quantify the probability of observing cancer and non-cancer effects in a potentially exposed population. Two types of toxicity values are used to express a COPCs dose-response-effect relationship:

· Slope Factor (SF), expressed in the units of (mg/kg-day)^-1 for non-radiological contaminants and (pCi)^-1 for radiological contaminants for estimating the likelihood of carcinogenic effects
· Reference Dose (RfD), reported in mg/kg-day, or Reference Concentration (RfC) expressed in mg/m³, for estimating possible non-carcinogenic effects from non-radiological contaminants

In general, SF and RfD or RfC values are derived from long-term animal studies. These studies incorporate uncertainty factors to compensate for extrapolation of observed adverse effects in laboratory animals to estimate possible adverse effects in humans. If adequate human data from epidemiological studies are available, the human data are used to reduce uncertainty in deriving animal toxicity values.

The toxicity assessment component of this baseline human health risk assessment is dependent upon the use of EPA-derived toxicity values. As specified (EPA 1989a), the resource hierarchy for selection of the most current and appropriate toxicity values is, in descending order, the following:

· Integrated Risk Information System (IRIS), an on-line database maintained by EPA
· EPA National Center for Environmental Assessment (NCEA) guidance documents, general toxicology information, extrapolations, and guidance for contaminants without toxicity values
· Health Effects Assessment Summary Tables (HEAST), published by the EPA
· EPA criteria documents, constituent-specific drinking water criteria, surface water criteria, and ambient air quality criteria documents
· Agency for Toxic Substance and Disease Registry (ATSDR) toxicological profiles, constituent-specific literature reviews of the use/production, chemical properties, toxicology, analytical methodology, and regulatory status of a constituent

Non-carcinogenic toxicity effects information for the COPCs are listed in Table 5.1 and Table 5.2. Carcinogenic toxicity effects for the non-radiological COPCs are listed in Table 6.1 and Table 6.2. Carcinogenic toxicity information for radiological COPCs is listed in Table 6.3 and Table 6.4.

Cancer risks are expressed as the incremental probability of an individual developing cancer over a lifetime as a result of exposure to the potential carcinogen (i.e., excess individual lifetime cancer risk). In carcinogen assessment, EPA evaluates the available data to determine the likelihood that an agent is a human carcinogen. Under the revised carcinogen risk assessment guidelines (EPA 1999), standard descriptors are used as part of the weight-of-evidence narrative. These standard descriptors are summarized as follows:

Carcinogenic to humans – when there is convincing evidence demonstrating causality between human exposure and cancer, or when there is compelling evidence of causality in animals and mechanistic information in animals and humans demonstrating similar modes of action.

Likely to be carcinogenic to humans – when the available data are adequate to demonstrate carcinogenic potential to humans.

Suggestive evidence of carcinogenicity, but not sufficient to assess human carcinogenic potential – when the evidence from either human or animal data is only suggestive of carcinogenicity. In such cases data is insufficient to determine dose-responses or to determine human carcinogenic potential.

Data are inadequate for an assessment of human carcinogenic potential – when available data are inadequate to perform an assessment. Often there is either a lack of pertinent or useful data or there is evidence of conflicting data.

Not likely to be carcinogenic to humans – when the data are considered sufficiently strong for making a conclusion that there is no carcinogenic human hazard concern.

Most of the available toxicity information (e.g. IRIS) was developed prior to the implementation of the revised cancer guidelines. This toxicity information is based on a EPA's previous classification scheme of the overall weight-of-evidence:

Group A - Human Carcinogen - Sufficient evidence from epidemiological studies substantiated by causal association between exposure and carcinogenicity.

Group B1 - Probable Human Carcinogen - Limited evidence of carcinogenicity in humans from available epidemiological data.

Group B2 - Probable Human Carcinogen - Sufficient evidence of carcinogenicity in animals, but inadequate or no evidence in humans.

Group C - Possible Human Carcinogen - Limited evidence of carcinogenicity in animals.

Group D - Not Classified - Inadequate evidence of carcinogenicity in animals to support classification.

Group E - Not a Human Carcinogen - No evidence of carcinogenicity in at least two adequate animal tests in different species or in both epidemiological and animal studies.

Based on the evidence that a constituent is a known or likely to be a human carcinogen, the EPA calculates a toxicity value that defines a quantitative relationship between dose and response (i.e., SF). An SF converts estimated daily intakes averaged over a human lifetime of exposure directly to incremental risk of an individual developing cancer. A critical assumption of this approach is that the dose-response relationship is a linear relationship in the low-dose portion of the dose-response curve. Under this assumption, the SF is a constant and risk is directly related to intake. Thus, the linear form of the carcinogenic risk equation is usually applicable for estimating site risks. This linear low-dose equation is defined for non-radiological contaminants as:

where:
Risk = a unitless probability (e.g., 1 ´ 10^-6) of an individual developing cancer over a lifetime
CDI = chronic daily intake averaged over 70 years (mg/kg-day)
SF = slope factor, expressed in (mg/kg-day)^-1

The collective carcinogenic risk from exposure to several non-radiological contaminants is calculated by adding the individual cancer risks for each constituent in the medium identified in each appropriate exposure pathway assessment and then summing the total carcinogen risk for all relevant exposure pathways.

where:
Risk_T = the total cancer risk, expressed as a unitless probability, and
Risk_ij = the risk estimate for the i^th constituent in the j^th exposure medium pathway

The resulting summation of constituent-specific cancer risks is a very conservative upper-bound estimate of cancer risk for the following reason. Each SF is an upper 95^th percentile estimate of potency, and, because percentiles of probability distributions are not strictly additive, the total cancer risk estimate becomes more conservative as the number of cancer risk estimates increases. While this may appear to be overly conservative, this method is used to ensure that carcinogenic risks will not be underestimated.

Likewise, the increased lifetime cancer risk from radiological contaminants is given by the following equation:

where:
Risk = a unitless probability (e.g., 1 ´ 10^-6) of an individual developing cancer over a lifetime
Intake = total lifetime intake above background (pCi)
SF = slope factor, expressed in (pCi)^-1

The total cancer risk from both radiological and non-radiological contaminants is calculated by summing the individual cancer risks for all contaminants (both radiological and non-radiological) across all exposure media and pathways.

To evaluate non-carcinogenic effects, a chronic RfD or RfC is an estimate of the daily exposure to a human population, including any sensitive subpopulation, that is unlikely to cause an increased incidence of deleterious health effects during a lifetime of exposure. Chronic RfD or RfC values are specifically developed to be protective for long-term exposure to a constituent.

To characterize low-dose exposure effects, the "no observed adverse effect level" (NOAEL) and the "lowest observed adverse effect level" (LOAEL) are evaluated. The NOAEL is an exposure level where there are no statistically or biologically significant increases in the frequency or severity of adverse effects in the exposed population. The LOAEL is the lowest exposure dose in a dose-response experiment at which there are statistically or biologically significant increases in severity or frequency of adverse effects in the exposed population.

In arriving at RfD or RfC toxicity values, the NOAEL or LOAEL is divided by additional factors to account for uncertainties in extrapolation from subchronic to chronic exposures and from uncertain species-to-species toxicity relationships. These uncertainty factors can range from 1 to 10,000 based on the degree of exposure. Uncertainty factors are presented for the COPC RfDs in Table 5.1 and Table 5.2.

For non-carcinogenic contaminants, the measure used to describe the potential for non-carcinogenic toxicity to occur in an individual is evaluated by comparing the estimated exposure level over a specified time period (e.g., lifetime) with the appropriate non-cancer toxicity value (i.e., RfD or RfC).

This ratio of exposure to toxicity is called a non-cancer hazard quotient (HQ):

where:
HQ = hazard quotient
CDI = chronic daily intake (mg/kg-day)
RfD = Reference Dose

The non-carcinogenic hazard quotient assumes that there is a level of exposure (i.e., RfD or RfC) below which it is unlikely for even sensitive subpopulations to experience adverse health effects.

For assessing the health impacts of several non-carcinogenic contaminants, RfDs or RfCs are compared to exposure-specific intake rates of each COPC. A summation of these hazard quotients is termed the hazard index (HI). The aggregate HI is expressed as:

where:
HI_T = total hazard index for exposure scenarios for an individual
CDI_ij = chronic daily exposure for the i^th constituent in the j^th exposure pathway
RfD_i = Reference dose for the i^th constituent

If this ratio of the daily intake to the RfD or RfC exceeds 1.0 (unity) for the defined exposure scenario, this provides an indication that the exposed receptor may be subject to an adverse health impact and that further investigation should be undertaken. If the ratio is below unity, then it is generally assumed that no adverse impact to human health has or will occur.

The HI approach does have limitations and should be interpreted carefully based on the known aspects of additive toxic effects from exposure to mixtures of chemicals. First, because both the HQ and HI are ratios, after unity has been exceeded, the magnitude of the index has little bearing on the potential severity of adverse effects that may be anticipated. A HI of five does not indicate the non-cancer hazard is greater than a HI of three. Secondly, it is inappropriate to sum non-cancer hazard quotients for contaminants that do not have similar toxic modes of action or that do not affect the same organ system. Additionally, there may be synergistic effects, which, though not directly affecting the same organ system, may increase the risk from one contaminant based on the presence or effect of some other contaminant.

6.0 Risk Characterization

In this section, the exposure assessment from Section 4 and the toxicity assessment from Section 5 are combined in order to assess the potential non-cancer health hazards and cancer risks based on the potential exposure. Section 6.1 presents the non-cancer health hazards to the target receptors from each medium. Section 6.2 presents the cancer risks from non-radiological COPCs to the target receptors from each medium. In Section 6.3, the total health hazards and non-radiological risks from all media are assessed. The total radiological cancer risk and dose assessment from exposures to radionuclides, particularly cesium-137, in environmental media is presented in Section 6.4. The total cancer risk from both radiological and non-radiological COPCs is addressed in Section 6.5. Section 6.6 assesses the potential contaminants and media that present the greatest concern and may require consideration of remedial actions. A discussion of uncertainty in the risk assessment is provided in Section 6.7.

The potential health concerns identified in this section are the following:

Potential Non-Cancer Health Hazards:
Groundwater
· current off-site young child drinking groundwater with arsenic, manganese, and trichloroethene (see Section 6.1.1)

Fish
· current off-site recreational anglers eating locally caught fish with PCBs or mercury (see Section 6.1.3)
· future recreational anglers (on- and off-site, adult and child) eating locally caught fish with PCBs or mercury (see Section 6.1.3)

Potential Cancer Health Risks:
Fish
· future on-site residents and on-site recreational anglers (adult and child, in each case) eating fish with PCBs caught on site (see Section 6.2.3)
· current off-site residents drinking groundwater with arsenic and trichloroethene (see Section 6.2.1)
· current or future recreational hunters eating deer meat from locally caught deer containing cesium-137 (see Section 6.4.2)

6.1 Non-Cancer Health Hazards

In this section, the health hazards related to COPCs in each medium are addressed. For each target population, the exposure to the RME individuals is evaluated as a conservative estimate of the health hazards.

6.1.1 Groundwater

Current off-site residents may be exposed to contaminants in the off-site groundwater if they are using private wells as their drinking water and household-use source. The groundwater in the area is classified as Class GA (fresh groundwaters) by the NYSDEC (6 NYCRR Part 701), and, though residents in the off-site area near the Peconic River between Schultz Road (Wading River Road) and the site perimeter have been offered public water hookups, private wells may still be present. Some private wells are known to be currently used for drinking purposes along North Street but outside the area defined by the VOC plume. Future on-site residents may also be exposed to contaminants in on-site groundwater in the unlikely event that the site near the Peconic River is ever developed for residential housing and the use of residential wells was permitted.

The non-cancer health hazards for both future on-site and current off-site residents from groundwater are summarized in Tables 7a.1.RME through 7a.6.RME for the reasonable maximum exposed individuals. For off-site residents, the hazard quotients for the adult, young child and older child are greater than one (1.6, 4.9, and 2.2, respectively). About 90 percent of the hazard quotient is due to arsenic, manganese, and trichloroethene from drinking groundwater.

For potential future on-site residents, the hazard quotient for the young child resident is 1.4. Arsenic contributes the most to the hazard quotients, and arsenic, manganese, and thallium from drinking groundwater combine for over 90 percent of the health hazard, though individually each has a hazard quotient less than one. The hazard quotients for the future on-site resident adult and older child are less than one (0.45 and 0.59, respectively). Arsenic and manganese in groundwater are likely due to naturally occurring arsenic and manganese in the soil and are not thought to be site-related. It should also be noted that the concentrations of arsenic in groundwater are below the established New York State groundwater standard of 25 m g/L (6 NYCRR Part 703). Though manganese in some of the groundwater samples are above the New York State groundwater standard of 300 µg/L, these may likely be due to abnormally high suspended soil particulates in a few samples. The groundwater in the area is classified as Class GA (fresh groundwaters) by the NYSDEC (6 NYCRR Part 701). To assure future safe drinking water, residents along the river in this area have been provided connection to the public water supply, and groundwater monitoring will continue.

Trespassers to BNL or recreational anglers and hunters that are not riverside residents with private wells are not exposed to groundwater contaminants.

Health hazards from groundwater based on CTE exposures are presented in Tables 7a.1.CTE through 7a.6.CTE. All hazard quotients are less than (1) for all receptors based on CTE exposure factors except for the off-site young child (1.9). The hazard quotient for the off-site resident adult, and older child, based on CTE exposures, are 0.79 and 0.85, respectively. The hazard quotient for the future on-site adult, young child, and older child resident are 0.22, 0.54, and 0.23, respectively. Since the hazard quotient based on RME exposure factors is almost entirely due to drinking groundwater, the difference in RME and CTE hazard quotients is due to the difference in assumed drinking water ingestion rates (2.0 L/day and 1.4 L/day for adults and older children, and 1.3 L/day and 0.74 L/day for a young child).

Though the groundwater data used in this risk assessment are from wells that both characterize and delineate the potential contamination from OU V and the Peconic River, individual wells and well depths may have higher concentrations of some contaminants whereas other wells or depths may have higher concentrations of other contaminants. For example, the low-level VOC plume is located at a depth of approximately 200 feet bls. The data set contains data from monitoring wells located in both the upper and lower portions of the deep aquifer. The range of these monitoring well screen intervals compare well with the range of screen intervals of domestic wells reported for the area. The potential uncertainty in the risk assessment concerning the use of the data from an extended area and various well depths is addressed in Section 6.7 of this report.

6.1.2 Soil

Future on-site residents may also be exposed to contaminants in on-site soils in the unlikely event that the site near the Peconic River was ever developed for residential use and current off-site residents may also be exposed to soils along the river if the residents live adjacent to the Peconic River. Soil exposure might come through incidental ingestion of soils, dermal contact with contaminated soils, or inhalation of airborne particulates. Likewise, trespassers may come into contact with contaminated soils if engaging in activities along the Peconic River.

The non-cancer health hazards for future on-site residents, current trespassers, and current off-site residents are summarized in Tables 7a.7.RME through 7a.13.RME for the reasonable maximum exposed individuals. All hazard quotients due to soil exposures are less than 0.1, which is well below the EPA target level of one. The RME hazard quotients for the off-site resident adult, young child, and older child are 0.0056, 0.048, and 0.011, respectively. The RME hazard quotients of the potential future on-site resident adult, child, and older child and current trespasser are 0.0099, 0.085, 0.019, and 0.0036, respectively. The non-cancer hazard quotients from soil based on CTE exposure factors are summarized in Tables 7a.7.CTE through 7a.13.CTE for the future on-site residents and current trespassers. The CTE hazard quotients for the off-site resident adult, young child, and older child are 0.0024, 0.022, 0.0048, respectively. The CTE hazard quotients of the potential future on-site resident adult, child, and older child and current trespasser are 0.0031, 0.028, 0.0061, and 0.00023, respectively.

6.1.3 Fish

Current off-site and future on-site recreational anglers may be exposed to contaminants in the fish they catch and eat. Riverside residents who are also recreational anglers may be exposed to contaminants through other media and pathways as well as fish. Riverside residents, though not necessarily recreational anglers, may still be exposed to contaminants in fish through the occasional consumption of on-site or off-site fish. The hazard quotient for RME individuals was calculated assuming that the adult and older child recreational angler eats 25 g/day of local caught fish (20 lb per year), the young child recreational angler eats half that amount, whereas the occasional RME consumer is considered to eat 6.5 g/day (5.2 lb per year).

The non-cancer health hazards for future on-site and current off-site recreational anglers and residents occasionally consuming fish are summarized in Tables 7a.14.RME through 7a.25.RME for the reasonable maximum exposed individuals. The hazard quotients for future on-site and current off-site recreational anglers are all greater than one. The hazard quotients for future on-site recreational anglers (62, 140, and 120 for the adult, young child, and older child, respectively) are greater than those for the current off-site recreational anglers (3.4, 7.9, and 6.8 for the adult, young child, and older child, respectively). The hazard quotients for future on-site and current off-site residents assumed to occasionally consume locally caught fish are greater than one for all but the off-site adult resident. The hazard quotients for the future on-site residents who are not recreational anglers but still consume local caught fish are 16, 75, and 32 for the adult, young child, and older child, respectively. The hazard quotients for the off-site residents who are not recreational anglers but still consume local caught fish are 0.88, 4.1, and 1.8 for the adult, young child, and older child, respectively. The on-site hazard quotients are principally due to PCBs in fish, whereas those for off-site are due more to mercury than PCBs. Whereas the off-site fish tissue concentration data were based on edible fish tissue, edible fish tissue data was not available for the on-site areas. Therefore, whole body fish tissue data were used as a conservative estimate of organic contaminant (e.g., PCB) exposures from on-site fish consumption, though this may underestimate potential mercury exposure. Off-site edible fish tissue data does not include fish from on-site Area D above the gauging station. Since these fish had high levels of PCBs in whole body samples (maximum of 6 parts per million [ppm]), it is likely that they would have had higher concentrations in their edible tissue also. The potential uncertainty in the risk assessment due to this data gap is assessed in Section 6.7.

Data for contaminants in edible fish tissue from the on-site Area D of the Peconic River that is accessible to off-site receptors are under-represented in the data set used for the off-site receptors. Since the concentrations of contaminants, particularly PCBs, were generally greater above the gauging station, the exposure concentrations used to represent the edible fish tissue concentrations may have been underestimated. An analysis of the uncertainty due to this lack of data (see Section 6.7) indicate that, for the off-site receptors, the non-cancer health hazard from fish consumption may be up to 2.5 times greater, but the health hazard would still be much less than that reported for a potential future on-site resident or recreational fisher.

For CTE individuals it was assumed that the adult and older child recreational angler eats eight g/day of locally caught fish (6.4 lb per year), the young child recreational angler eats half that amount, whereas the occasional CTE resident was considered not to eat any locally caught fish. The non-cancer health hazards, based on CTE exposures for recreational anglers are summarized in Tables 7a.1.CTE through 7a.25.CTE. Hazard quotients for recreational anglers are greater than one for all but the off-site adult recreational angler based on these exposure assumptions. The hazard quotient for future on-site recreational anglers (13, 31, and 27 for the adult) are greater than those for current off-site recreational anglers (0.91, 2.1, and 1.8 for the adult, young child, and older child, respectively). Hazard quotients based on the CTE exposures for residents who are not recreational anglers are all zero.

6.1.4 Surface Water

Future on-site residents may also be exposed to contaminants in on-site Peconic River surface water in the unlikely event that the site near the Peconic River was ever developed for residential use. Surface water exposure may come through incidental ingestion of surface water and dermal contact with contaminated surface water. Likewise, trespassers may come into contact with contaminated surface water if engaging in activities along the Peconic River. Current off-site residents who live along the Peconic River may also be exposed to contaminants in surface water of the Peconic River.

The non-cancer health hazards for future on-site residents, current trespassers, and current off-site residents are summarized in Tables 7a.26.RME through 7a.32.RME for the reasonable maximum exposed individuals. All hazard quotients due to surface water exposures are less than 0.06, which is well below the EPA target level of one. The RME hazard quotients for the future on-site resident adult, young child, and older child, current trespasser, and current off-site resident adult, young child, and older child are 0.0064, 0.058, 0.027, 0.011, 0.0036, 0.033, and 0.015, respectively. The non-cancer hazard quotients from surface water based on CTE exposure factors are summarized in Tables 7a.26.CTE through 7a.32.CTE for the reasonable maximum exposed individuals. The CTE hazard quotients for the future on-site resident adult, young child, and older child, current trespasser, and current off-site resident adult, young child, and older child are 0.00088, 0.013, 0.0061, 0.0016, 0.00046, 0.0074, and 0.0035, respectively.

6.1.5 Sediment

Future on-site residents or trespassers to the site could be exposed to contaminants in sediment while engaging in activities in the Peconic River or, during periods when the river is dry, in the riverbed. Exposure to contaminants in sediment may result from incidental ingestion of sediment, dermal exposure to sediment, or inhalation of airborne particulates during periods when the river is dry.

The non-cancer health hazards for future on-site residents, current trespassers, and current off-site residents are summarized in Tables 7a.33.RME through Table 7a.39.RME for the reasonable maximum exposed individuals. All hazard quotients due to sediment exposures for the reasonable maximum exposed individuals are less than one. The highest is for the future resident young child (i.e., hazard quotient of 0.33). The RME hazard quotients for the future on-site resident adult and older child are 0.016 and 0.073, respectively. The RME hazard quotients for the current trespasser and resident adult, young child, and older child are 0.031, 0.026, 0.53, and 0.12, respectively. The non-cancer health hazards from sediment exposure are summarized in Tables 7a.33.CTE through Table 7a.39.CTE. All hazard quotients based on CTE exposure factors are less than one. The CTE hazard quotients for the future on-site resident adult, young child, and older child, current trespasser, and current off-site resident adult, young child, and older child are 0.0014, 0.049, 0.011, 0.0028, 0.0015, 0.052, and 0.011, respectively.

6.2 Non-radiological Cancer Risks

In this section, the cancer risks related to non-radiological COPCs in each medium are addressed. Cancer risks due to radiological COPCs are addressed in Section 6.4. The total cancer risk is presented in Section 6.5. For each target population, the exposure to the RME individuals is evaluated as a conservative estimate of the cancer risks.

6.2.1 Groundwater

Current off-site residents may be exposed to contaminants in the off-site groundwater if they are using private wells as their drinking water and household-use source. The groundwater in the area is classified as Class GA (fresh groundwaters) by the NYSDEC (6 NYCRR Part 701). Though residents in the off-site area near the Peconic River have been offered public water hookups, private wells may still be present. Some private wells are known to be currently used for drinking purposes along North Street, though these are not within the area of the VOC plume. Future on-site residents may also be exposed to contaminants in on-site groundwater in the unlikely event that the site near the Peconic River was ever developed for residential use.

The cancer risks for both future on-site and current off-site residents from groundwater are summarized in Tables 7b.1.RME through b.6.RME for the reasonable maximum exposed individuals. For off-site residents, the cancer risks for the adult, young child, and older child are 1.9´ 10^-4, 1.1´ 10^-4, and 5.6´ 10^-5, respectively. The cancer risks for the off-site adult and young child are just above the EPA target range of 1´ 10^-4 to 1´ 10^-6. Over 50 percent of the cancer risk is due to arsenic from drinking groundwater and about 40 percent of the cancer risk is due to trichloroethene. For future on-site residents, the cancer risks range for the adult, young child, and older child are 4.1´ 10^-5, 2.4´ 10^-5, and 1.1´ 10^-5, respectively. Over 70 percent of the cancer risk is due to arsenic from drinking groundwater and trichloroethene contributes about 10 percent of the risk.

Trespassers to the site or recreational anglers and hunters that are not riverside residents with private wells are not exposed to groundwater contaminants.

Cancer risks from groundwater based on CTE exposures are presented in Tables 7b.1.CTE through 7b.6.CTE. Cancer risks based on CTE exposures are less than those based on the RME exposures and are all within the EPA target range of 1´ 10^-4 to 1´ 10^-6. The cancer risks are 2.6´ 10^-5, 4.4´ 10^-5, and 2.0´ 10^-5 for the current off-site resident adult, young child, and older child, respectively, and 5.7´ 10^-6, 9.4 ´ 10^-6, and 4.2´ 10^-6 for the future off-site resident adult, young child, and older child, respectively.

6.2.2 Soil

Future on-site residents may also be exposed to contaminants in on-site soils in the unlikely event that the site near the Peconic River was ever developed for residential use and current off-site residents may also be exposed to soils along the river if the residents live adjacent to the Peconic River. Soil exposure may come through incidental ingestion of soils, dermal contact with contaminated soils, or inhalation of airborne particulates. Likewise, trespassers may come into contact with contaminated soils if engaging in activities along the Peconic River.

The cancer risks for future on-site residents, current trespassers, and current off-site residents are summarized in Tables 7b.7.RME through 7b.13.RME for the reasonable maximum exposed individuals. Arsenic was the only non-radiological COPC identified in surface soils adjacent to the Peconic River. The cancer risk for future on-site resident adults and young children were greater than 1´ 10^-6 for reasonable maximum exposed individuals (2.0´ 10^-6 and 3.3´ 10^-6, respectively). These are within the EPA target range of 1´ 10^-4 to 1´ 10^-6. The cancer risk for future on-site resident older children was less than 1´ 10^-6 (7.6 ´ 10^-7). The cancer risk for the trespasser was 1.4´ 10^-7. The cancer risks for the off-site resident adult, young child, and older child are 1.1´ 10^-6, 1.9´ 10^-6, and 4.3´ 10^-7, respectively. The cancer risks from soil based on CTE exposure factors are summarized in Tables 7b.7.CTE through 7b.13.CTE for the future on-site residents, current trespassers, and current off-site residents. The cancer risk is less than 1´ 10^-6 for all based on CTE exposure factors except the future on-site resident young child with a cancer risk of 1.1´ 10^-6. The cancer risk based on CTE exposure factors for the adult and older child future residents are 1.9´ 10^-7 and 2.4´ 10^-7, respectively. The cancer risk based on CTE exposure factors for the adult, young child, and older child current off-site residents are 1.5´ 10^-7, 8.7´ 10^-7, and 1.9´ 10^-7, respectively. The cancer risk based on CTE exposure factors for the on-site trespasser is 9.0´ 10^-9.

6.2.3 Fish

Current off-site and future on-site recreational anglers may be exposed to contaminants in the fish they catch and eat. Riverside residents who are also recreational anglers may be exposed to contaminants through other media and pathways as well as fish. Riverside residents, though not necessarily recreational anglers, may still be exposed to contaminants in fish through the occasional consumption of on-site or off-site fish. The cancer risk for RME individuals was calculated assuming that the adult and older child recreational angler eats 25 g/day of local caught fish (20 lb per year) and the young child recreational angler eats half that amount, whereas the occasional RME consumer was considered to eat 6.5 g/day (5.2 lb per year).

The cancer risks for future on-site and current off-site recreational anglers and residents occasionally consuming fish are summarized in Tables 7b.14.RME through 7b.25.RME for the reasonable maximum exposed individuals. The cancer risks for hypothetical future on-site residents and future on-site recreational anglers that eat on-site fish are greater than 1´ 10^-4. The cancer risks for the future on-site resident recreational anglers (adult, older child, younger child) are 1.0´ 10^-3, 4.1´ 10^-4, and 4.8´ 10^-4. For the future on-site resident occasionally consuming fish, the cancer risks are 2.7´ 10^-4, 1.1´ 10^-4, and 2.5´ 10^-4 (adult, older child, younger child, respectively). PCBs contribute over 90 percent to the estimated cancer risk. The cancer risk for off-site anglers and off-site residents who consume locally caught fish is less than 1´ 10^-4. The highest cancer risk for off-site areas (1.6´ 10^-5) is for the off-site adult recreational angler consuming 20 lb per year of locally caught fish. The cancer risks for the off-site recreation angler young child and older child and the off-site resident adult, young child, and older child that occasionally consume local caught fish are 7.5´ 10^-6, 6.4´ 10^-6, 4.2´ 10^-6, 3.9´ 10^-6, and 1.7´ 10^-6, respectively. The greatest contributors to this risk are PCBs. Whereas the fish tissue concentration data used for off-site receptors were based on edible fish tissue, edible fish tissue data was not available for the on-site upstream areas. Therefore, whole body fish tissue data were used as a conservative estimate of organic contaminant (e.g., PCB) exposures from fish consumption by future on-site receptors, though they may underestimate mercury exposure.

Data for contaminants in edible fish tissue from the on-site Area D of the Peconic River that is accessible to off-site receptors are under-represented in the data set used for the off-site receptors. Since the concentrations of contaminants, particularly PCBs, were generally greater above the gauging station, the exposure concentrations used to represent the edible fish tissue concentrations may have been underestimated. An analysis of the uncertainty due to this lack of data (see Section 6.7) indicate that, for the off-site receptors, the cancer risk from fish consumption may be almost an order of magnitude greater, but the cancer risk would still be much less than that reported for a potential future on-site resident or recreational fisher.

For CTE individuals, it was assumed that the adult and older child recreational angler eats eight g/day of locally caught fish (6.4 lb per year) and the young child recreational angler eats half that amount, whereas the CTE resident was considered not to eat any locally caught fish. The cancer risks based on CTE exposures for recreational anglers are summarized in Tables 7b.14.CTE through 7b.25.CTE. Cancer risks for CTE on-site recreational anglers is 1.0´ 10^-4 for on-site recreational angler young children. Cancer risks for CTE on-site recreational angler adults and older children are 6.7´ 10^-5 and 8.9´ 10^-5, respectively. Cancer risks for CTE off-site recreational anglers are less than 1´ 10^-5 (1.8´ 10^-6 for a young child, 1.5´ 10^-6 for an older child, and 1.1´ 10^-6 for an adult).

6.2.4 Surface Water

Future on-site residents may also be exposed to contaminants in the unlikely event that the site near the Peconic River was ever developed for residential use. Surface water exposure may come through incidental ingestion of surface water and dermal contact with contaminated surface water. Likewise, trespassers may come into contact with contaminated surface water if engaging in activities along the Peconic River. Current off-site residents who live along the Peconic River may also be exposed to contaminants in surface water of the Peconic River.

The cancer risks for future on-site residents, current trespassers, and off-site residents are summarized in Tables 7b.26.RME through 7b.32.RME for the reasonable maximum exposed individuals. All cancer risks due to surface water exposures are less than 1´ 10^-6 except for the future on-site resident young child with a cancer risk of 1.0´ 10^-6 and the off-site resident young child with a cancer risk of 1.3´ 10^-6 due to incidental ingestion of arsenic in surface water during activities related to the Peconic River such as swimming or wading. The cancer risk for the future on-site resident adult and older child, current trespasser, and current off-site resident adult and older child are 5.7´ 10^-7, 4.8´ 10^-7, 2.1´ 10^-7, 7.0´ 10^-7, and 5.9´ 10^-7, respectively. All risks are within or below the EPA target range of 1´ 10^-6 to 1´ 10^-4. The cancer risks from surface water based on CTE exposure factors are summarized in Tables 7b.26.CTE through 7b.32.CTE for the future on-site residents, current trespassers, and current off-site residents. All are less than 1´ 10^-6. The cancer risks based on CTE exposures for the future on-site resident adult, young child, and older child are 1.7´ 10^-8, 1.6´ 10^-7, and 8.3´ 10^-8, respectively. The cancer risks based on CTE exposures for the trespasser and the off-site resident adult, young child, and older child are 2.3´ 10^-8, 8.9´ 10^-8, 2.9´ 10^-7, and 1.3´ 10^-7, respectively.

6.2.5 Sediment

The cancer risks for future on-site residents, current trespassers, and current off-site residents are summarized in Table 7b.33.RME through Table 7b.39.RME for the reasonable maximum exposed individuals. The RME cancer risks from sediment exposure to future on-site residents are 1.3´ 10^-6, 4.7´ 10^-6, and 1.2´ 10-6 for an adult, young child, and older child, respectively. The cancer risk to on-site trespassers is 4.9´ 10^-7. The cancer risk to off-site residents are 1.1´ 10^-6, 4.2´ 10^-6, and 9.6´ 10^-7 for an adult, young child, and older child, respectively. All cancer risks are within or below the EPA target range of 1´ 10^-4 to 1´ 10^-6. The greatest contributor to sediment cancer risks is arsenic from incidental ingestion. The cancer risks from sediment exposure based on CTE exposure factors are summarized in Table 7b.33.CTE through Table 7b.39.CTE. All cancer risks based on CTE exposure factors are less than 1´ 10^-6. The cancer risks based on CTE exposures are 2.4´ 10^-8, 5.2´ 10^-7 and 1.2´ 10-7 for future on-site resident adults, young children, and older children, respectively, and are 2.2´ 10^-8, 4.9´ 10-7, and 1.1´ 10^-7 for off-site resident adults, young children, and older children. The CTE cancer risk to on-site trespassers is 3.1´ 10^-8.

6.3 Total non-radiological Cancer Risks and Health Hazards

In this section the total cancer risks and total non-cancer health hazards based on chemical contaminants are presented for each receptor population across all media and exposure pathways. Target organs for non-cancer health hazards are indicated, and organ-specific total health hazards are also presented as applicable.

6.3.1 Off-Site Resident Recreational Anglers

The greatest total non-radiological risks and health hazards from exposure to contaminants in off-site media are to off-site residents that also engage in recreational angling and consume a significant amount of locally caught fish (Table 8.1.RME through Table 8.3.RME). Total non-radiological cancer risks to adult (2.1´ 10^-4) and young child (1.3´ 10^-4) resident recreational anglers are just above the EPA target range of 1´ 10^-4 to 1´ 10^-6, whereas the total non-radiological cancer risks to the older child (4.2´ 10^-5) resident anglers is within the EPA target range of 1´ 10^-4 to 1´ 10^-6. Non-cancer hazard quotients are greater than one for each of these receptors (5.0, 13, and 9.1, respectively) based on RME exposure factors. Most of the non-cancer hazard quotients are from mercury in fish tissue; lesser contributions are from PCBs in fish tissue and arsenic, manganese, and trichloroethene in groundwater used for drinking. The total hazard index based on central nervous system effects is greater than one (2.8, 7.2, and 5.5 for the adult, young child, and older child, respectively) and is due to mercury in fish as well as manganese in groundwater. The total hazard indices based on immune system effects are greater than one for the young child (2.1) and older child (1.8), due mostly to PCBs in fish, but less than one for the adult (0.88). The total hazard indices based on effects to the skin are 1.9 for the young child, 0.77 for the older child, and 0.58 for the adult, due mostly to arsenic in groundwater. Hazard indices for the liver and kidney are 2.2 for the young child, 1.0 for the older child, and 0.7 for the adult. Hazard indices for other specific organs or targets are less than one. Total non-radiological risks and health hazards based on CTE exposure factors are presented in Table 8.1.CTE through Table 8.3.CTE. Non-cancer hazard quotients are greater than one for off-site resident recreational anglers based on CTE exposure factors (1.7, 4.2, and 2.7 for adults, young children, and older children, respectively) due mostly to mercury in fish tissue and cancer risks based on CTE exposure factors are 2.8´ 10^-5, 4.7´ 10^-5, and 2.2´ 10^-5for adults, young children, and older children, respectively, and are within the EPA target range of 1´ 10^-4 to 1´ 10^-6. The highest target-specific total hazard indices based on CTE exposure factors are for central nervous system effects (0.80, 1.9, and 1.5 for the adult, young child, and older child, respectively).

6.3.2 Off-Site Recreational Anglers

Off-site recreational anglers that are not riverside residents are principally exposed to contaminants through the consumption of fish in the off-site upstream area of the Peconic River. The total non-radiological cancer risks and non-cancer health hazards are summarized in Table 8.4.RME through Table 8.6.RME. Total non-radiological cancer risks to adult (1.6´ 10^-5), young child (1.3´ 10^-5), and older child (6.5´ 10^-6) resident anglers are all within the EPA target range of 1´ 10^-4 to 1´ 10^-6. Non-cancer hazard quotients are greater than one for each of these receptors (3.4, 7.9, and 682, respectively) based on RME exposure factors. Over 80 percent of the non-cancer hazard quotients are from mercury in fish tissue. The total hazard index based on central nervous system effects are greater than one (2.5, 5.8, and 5.0 for the adult, young child, and older child recreational anglers, respectively). Hazard indices based on other specific organs or targets (i.e., liver, immune system) are less than one. Total non-radiological risks and health hazards based on CTE exposure factors are presented in Table 8.4.CTE through Table 8.6.CTE. Non-cancer hazard quotients are greater than one for the young child recreational angler (2.1) and the older child recreational angler (1.8) based on CTE exposures but not for the adult recreational angler (0.91), with most of the hazard index related to central nervous system effects from mercury in fish (0.71, 1.7, and 1.4, respectively). Total non-radiological cancer risks based on CTE exposures for off-site anglers are 1.1´ 10^-6 for the adult, 1.8´ 10^-6 for the young child and 1.5´ 10^-6 for the older child. All are within the EPA target range of 1´ 10^-4 to 1´ 10^-6.

6.3.3 Off-Site Residents

Off-site residents that are not recreational anglers but still consume some fish caught in the off-site upstream section of the Peconic River may be exposed to contaminants in various environmental media. The total non-radiological cancer risks and non-cancer health hazards for the reasonable maximum exposed individuals are summarized in Table 8.7.RME through Table 8.9.RME. Cancer risks to adult residents (2.0´ 10^-4) and young child residents (1.3´ 10^-4) are just above the EPA target range of 1´ 10^-4 to 1´ 10^-6, whereas cancer risks to older child residents (6.0´ 10^-5) are within the EPA target range. Non-cancer hazard quotients are greater than one for each of these receptors (2.5, 9.6, and 4.1 respectively) based on RME exposure factors. Since the resident is still assumed to consume locally caught fish, most of the non-cancer hazard is still from mercury in fish tissue for the adult and older child resident. Arsenic, manganese, and trichloroethene in groundwater also contribute significantly to the hazard quotient for the young child. The highest organ or target-specific hazard indices are for central nervous system effects from mercury in fish, as well as manganese in groundwater and mercury in sediment. Total central nervous system hazard indices are 0.96, 4.3, 1.8 for the adult, young child, and older child resident, respectively. The total hazard indices based on effects to the skin are above one for the young child (1.9) but less than one for the adult (0.58) and the older child (0.77), and is mostly due to arsenic. The total hazard indices based on effects to the kidney and liver are above one for the young child (2.2) but not for the adult (0.7) and the older child (1.0). Total non-radiological risks and health hazards based on CTE exposure factors are presented in Table 8.7.CTE through Table 8.9.CTE. Based on CTE exposure factors, it is assumed that residents do not consume locally caught fish. The non-cancer hazard quotients are less than one for the adult and older child residents (0.80 and 0.87, respectively) but greater than one for the young child resident (2.0) based on these CTE exposure factors. Cancer risks based on CTE exposures are 2.7´ 10^-5, 4.5´ 10^-5, and 2.1´ 10^-5, respectively.

6.3.4 On-Site Tresspassers

Trespassers to on-site areas of the Peconic River can be exposed to contaminants in on-site sediment, surface water, and soils. The total non-radiological cancer risks and non-cancer health hazards for the reasonable maximum exposed on-site trespassers are summarized in Table 8.10.RME. Cancer risks to on-site trespassers (8.1´ 10^-7) are below the EPA target range. The total non-cancer health hazard (0.046) is also below one. The total non-radiological cancer risks and non-cancer health hazards based on CTE exposure factors for on-site trespassers are summarized in Table 8.10.CTE and are 5.9´ 10^-8 and 0.0068, respectively.

6.3.5 Future On-Site Resident Recreational Anglers

The greatest total non-radiological risks and health hazards from exposure to contaminants in on-site media are to future on-site residents that also engage in recreational angling and consume a significant amount of locally caught fish (Table 8.11.RME through Table 8.13.RME). Total non-radiological cancer risks to adult (1.1´ 10^-3), young child (5.2´ 10^-4), and older child (4.3´ 10^-4) future on-site resident anglers are all above the EPA target range of 1´ 10^-4 to 1´ 10^-6. The cancer risk is mostly due to PCBs in fish tissue. Non-cancer hazard quotients are greater than one for each of these receptors (62, 150, and 120, respectively) based on RME exposure factors. Most of the non-cancer hazard quotients are from PCBs in fish tissue. However, PCBs were measured in whole body fish tissue samples, not edible portions; thus, PCB exposure concentrations may be overestimated. The hazard quotient based on mercury in fish tissue was also above the 1.0 target level. Total hazard indices bases on central nervous system and immune system effects are greater than one for the future on-site resident recreational anglers. Central nervous system hazard indices are 3.2, 7.8, and 6.3, for the adult, young child, and older child, respectively, due almost exclusively to mercury in fish. The immune system hazard indices are 58, 140, and 120, respectively, due almost exclusively to PCBs in fish. The total hazard index for skin effects is equal to one for the young child (1.0) but less than one for the adult (0.32) and the older child 0.54), due mostly to arsenic in groundwater. Total non-radiological risks and health hazards based on CTE exposure factors are presented in Table 8.11.CTE through Table 8.13.CTE. Total non-radiological cancer risks for future on-site residential recreational anglers are 7.3´ 10^-5, 1.2´ 10^-4, and 9.4´ 10^-5 due mostly to PCBs in fish tissue and non-cancer hazard quotients are greater than one (14, 32, and 27, respectively) for off-site resident recreational anglers based on CTE exposure factors due to PCBs and mercury in fish tissue. The total central nervous system hazard indices based on CTE exposure factors are 0.82, 2.0, and 1.6 for the adult, young child and older child, respectively, and the total immune system hazard indices are 13, 29, and 25, respectively.

6.3.6 Future On-Site Recreational Anglers

Future on-site recreational anglers that are not riverside residents are principally exposed to contaminants through the consumption of fish in the on-site portion of the Peconic River. The total non-radiological cancer risks and non-cancer health hazards are summarized in Table 8.14.RME through Table 8.16.RME. Cancer risks to adult (1.0´ 10^-3), young child (4.8´ 10^-4), and older child (4.1´ 10^-4) hypothetical future on-site resident anglers are all above the EPA target range of 1´ 10^-4 to 1´ 10^-6. The cancer risk is mostly due to PCBs in fish tissue. Non-cancer hazard quotients are greater than one for each of these receptors (62, 140, and 120 respectively) based on RME exposure factors. Most of the non-cancer hazard quotients are from PCBs in fish tissue. However, PCBs were measured in whole body fish tissue samples, not edible portions; PCB concentrations may be overestimated. The hazard quotient for mercury in fish tissue was also above the 1.0 target level. The central nervous system hazard indices are 3.1, 7.2, and 6.1 for the adult, young child, and older child, respectively, due to mercury in fish. The immune system hazard indices are 58, 140, and 120, respectively, due to PCBs in fish. Total non-radiological risks and health hazards based on CTE exposure factors are presented in Table 8.14.CTE through Table 8.16.CTE. Cancer risks for future on-site recreational anglers are 6.7´ 10^-5, 1.0´ 10^-4, and 8.9´ 10^-5 for the adult, young child, and older child, respectively, due mostly to PCBs in fish tissue. None are greater than the EPA target range of 1´ 10^-4 to 1´ 10^-6. Non-cancer hazard quotients are greater than one (13, 31, and 27 for the adult, young child, and older child, respectively) for on-site resident recreational anglers based on CTE exposure factors due to PCBs and mercury in fish tissue. The total hazard indices based on central nervous system effects are 0.78, 1.8, and 1.6 for the adult, young child, and older child, respectively, due to mercury in fish. The total hazard indices based on immune system effects are 13, 29, and 25, respectively, due to PCBs in fish.

6.3.7 Future On-Site Residents

Future on-site residents that are not recreational anglers but still consume some fish caught in the off-site upstream section of the Peconic River may be exposed to contaminants in various environmental media. The total non-radiological cancer risks and non-cancer health hazards for the reasonable maximum exposed individuals are summarized in Table 8.17.RME through Table 8.19.RME. Cancer risks to adult (3.1´ 10^-4), young child (2.8´ 10^-4), and older child (1.2´ 10^-4) residents are all above the EPA target range of 1´ 10^-4 to 1´ 10^-6. This is principally due to consumption of fish containing PCBs that were caught on site. Non-cancer hazard quotients are greater than one for each of these receptors (17, 77, and 33 respectively) based on RME exposure factors. Since the hypothetical future resident was still assumed to consume locally caught fish, most of the non-cancer hazard is still from PCBs and mercury in fish tissue. Hazard indices based on central nervous system effects from mercury (0.92, 4.3, and 1.8 for the adult, young child, and older child, respectively) and on immune system effects from PCBs (15, 71, and 30, respectively) are greater than one for most of these future residents. The hazard index based on skin effects from arsenic is also greater than one for the young child (1.2). Total non-radiological risks and health hazards based on CTE exposure factors are presented in Table 8.17.CTE through Table 8.19.CTE. Based on CTE exposure factors, it was assumed that residents do not consume locally caught fish. The cancer risks based on CTE exposure factors to adult (5.9´ 10^-6), young child (1.1´ 10^-5), and older child (4.7´ 10^-6) residents are all within the EPA target range of 1´ 10^-4 to 1´ 10^-6. The non-cancer hazard quotients are less than one (0.22, 0.63, and 0.47 for the adult, young child, and older child, respectively) for the on-site residents based on these CTE exposure factors.

6.4 Radiological Risk Assessment

The computer code RESRAD was used to calculate radiological doses, for the inhalation and external gamma radiation pathways evaluated, and to estimate corresponding increased lifetime cancer risks (ILCR) for the identified potentially exposed populations for those pathways. RESRAD evaluated exposure through inhalation of soil or exposed sediment particulates and dusts, and external gamma exposure from radionuclides in soil or exposed sediment for each of the potentially exposed populations. Dose and risk estimates were calculated without using RESRAD for surface water ingestion, soil ingestion, sediment ingestion, consumption of locally caught fish, consumption of locally caught deer, and groundwater ingestion. In this section, dose and risk estimates are presented for exposures to the reasonable maximum exposed individuals.

6.4.1 Ingestion of Surface Water

Current off-site residents may be exposed to radiological contaminants in Peconic River surface water during periods when the off-site areas contain standing surface water. Future on-site residents may also be exposed to radiological contaminants in on-site Peconic River surface water in the unlikely event that the site near the Peconic River was ever developed for residential use. Surface water exposure may come through incidental ingestion of surface water. Dermal uptake of radionuclides from surface water does not represent a significant exposure pathway because of the low permeability of radionuclides and the additional shielding from the water. Trespassers may also come into contact with radionuclides in contaminated surface water if engaging in activities along the Peconic River. Current off-site residents who live along the Peconic River may also be exposed to radiological contaminants in surface water of the Peconic River.

The annual radiological doses from surface water for future on-site residents, current trespassers, and current off-site residents are summarized in Tables 9.1.RME through 9.19.RME for the reasonable maximum exposed individuals. The annual radiological dose due to surface water exposures is less than 0.01 for all receptors, which is well below the 15 mrem/yr EPA dose limit. The RME annual doses for the future on-site resident adult, young child, and older child, current trespasser, and current off-site resident adult, young child, and older child are 0.0026, 0.0061, 0.0061, 0.0026, 0.000058, 0.00014, and 0.00014, respectively. The annual radiological doses from surface water based on CTE exposure factors are summarized in Tables 9.1.CTE through 9.19.CTE. The CTE annual doses for the future on-site resident adult, young child, and older child, current trespasser, and current off-site resident adult, young child, and older child are 0.00037, 0.0014, 0.0014, 0.00037, 0.000011, 0.000045, and 0.000045, respectively.

The increased lifetime cancer risk from radionuclides in surface water for future on-site residents, current trespassers, and current off-site residents are summarized in Tables 9.1.RME through 9.19.RME for the reasonable maximum exposed individuals. The increased lifetime cancer risk due to surface water exposures is less than 2´ 10^-8 for all receptors, which is well below the EPA target range of 1´ 10^-4 to 1´ 10^-6. The increased lifetime cancer risk from radionuclides in surface water based on RME exposure factors for the future on-site resident adult, young child, and older child, current trespasser, and current off-site resident adult, young child, and older child are 1.1´ 10^-8, 5.0´ 10^-9, 5.0´ 10^-9, 2.1´ 10^-9, 5.7´ 10^-10, 2.7´ 10^-10, and 2.7´ 10^-10, respectively. The increased lifetime cancer risk from radionuclides in surface water based on CTE exposure factors are summarized in Tables 9.1.CTE through 9.19.CTE. The CTE increased lifetime cancer risk for the future on-site resident adult, young child, and older child, current trespasser, and current off-site resident adult, young child, and older child are 5.1´ 10^-10, 1.3´ 10^-9, 1.3´ 10^-9, 3.4´ 10^-10, 3.2´ 10^-11, 9.0´ 10^-11, and 9.0´ 10^-11, respectively.

6.4.2 Deer Meat Consumption

Hunting is not allowed on the BNL site; the area is posted and occasionally patrolled. However, hunting is permitted in off-site areas near the Peconic River and deer may migrate from on site to off-site areas. Cesium-137 has been detected at elevated concentrations in deer meat samples from deer on and near the BNL site and near the Peconic River. Several deer meat samples further than one mile from the site, but less than 10 miles, were also found with elevated cesium-137 levels, though most were at background levels, and the higher concentrations were generally found closer to the site. Therefore, deer meat consumption is considered for the future on-site resident and non-resident hunters as well as current off-site resident and non-resident hunters. It should be noted that BNL has a standing program that encourages local hunters to bring samples of meat from deer taken near the site to BNL for cesium-137 testing.

The dose through deer consumption is calculated as follows:

where:
Dose_deer = Effective dose from dietary consumption of deer (mrem/yr)
C_rad = Activity of radionuclide in deer (pCi/kg)
ACR = Annual Consumption Rate of deer (kg/year)
CF_rad = Radionuclide Conversion Factor for dose (mrem/pCi)

Deer meat samples from deer caught on-site or within a ten-mile radius of the site were considered for both the current off-site and future on-site hunters. The 95 percent UCL activity of cesium-137 in these deer is 2.28 pCi/g. The annual consumption rate for deer for adults and older children is 28.9 kg/year (64 lb/year) for RME hunters and 2.7 kg/year (6 lb/year) for CTE hunters. Young children in families of hunters are assumed to consume the same number of meals as the adults or older children but to consume meals of only half the size. Thus, the annual consumption rate for young children is assumed to be 14.45 kg/year and 1.35 kg/year for RME and CTE exposures, respectively. Residents who are not recreational hunters are not assumed to consume any locally caught deer meat. The annual dose from consumption of deer meat obtained within the vicinity of BNL by both RME future on-site and current off-site hunters is 4.9 mrem/yr for adults and older children and 2.5 mrem/year for younger children (Table 9.1.RME through Table 9.19.RME). The annual dose for CTE exposures is 0.07 mrem/year for adults and older children and 0.035 mrem/year for younger children (Table 9.1.CTE through Table 9.19.CTE). All annual doses are below the 15 mrem/year EPA dose limit.

The ILCRs from deer meat consumption are summarized in Table 9.1.RME through Table 9.19.RME for RME exposures and in Table 9.1.CTE through 9.19.CTE for CTE exposures. The ILCR from consumption of deer from the vicinity by both future on-site and current off-site residents for RME exposures is estimated at 1.1´ 10^-4 for adults, 2.2´ 10^-5 for older children, and 1.1´ 10^-5 for younger children The ILCR for CTE exposures is 4.7´ 10^-7 for adults, 3.2´ 10^-7 for older children, and 1.6´ 10^-7 for younger children. The estimated carcinogenic risk from this pathway was below the EPA recommended limits of 10^-4 to 10^-6 for all receptors except the adult hunter under RME exposure factors.

6.4.3 Fish Consumption

Though fishing is not allowed on the BNL site, fishing is permitted and does occur in off-site areas, predominantly in the downstream stretch, and fishing may occur in accessible on-site areas. Cesium-137 and other radionuclides were detected in edible fish tissue and, therefore, fish consumption was considered for the future on-site residents and anglers as well as the current off-site residents and anglers.

The annual radiological doses for future on-site and current off-site recreational anglers and residents occasionally consuming fish are summarized in Tables 9.1.RME through 9.19.RME for the reasonable maximum exposed individuals. The annual radiological doses for all receptors are less than one except for future on-site adult and older child recreational anglers. The annual doses for future on-site recreational anglers (1.1, 0.54, and 1.1 for the adult, young child, and older child, respectively, for RME exposures) are greater than those for the current off-site recreational anglers (0.39, 0.19, and 0.39 for the adult, young child, and older child, respectively, for RME exposures). The annual dose for future on-site and current off-site residents assumed to occasionally consume locally caught fish is less than 1.0 mrem/year. The annual dose from radionuclides in fish for the future on-site residents who are not recreational anglers but still consume local caught fish is 0.28 for the adult, young child, and older child. The annual dose from radionuclides in fish for the off-site residents who are not recreational anglers but still consume local caught fish is 0.10 for the adult, young child, and older child. The annual dose from fish is due to both cesium-137 and strontium-90 in fish tissue, though the annual dose is still well below the 15 mrem/year EPA dose limit.

The annual dose from radionuclides in fish, based on CTE exposures for recreational anglers are summarized in Tables 9.1.CTE through 9.19.CTE. The annual dose for recreational anglers are well below one mrem/year. The annual doses for future on-site recreational anglers (0.24, 0.12, and 0.24 for the adult young child, and older child, respectively, for CTE exposures) are greater than those for current off-site recreational anglers (0.094, 0.047, and 0.094 for the adult, young child, and older child, respectively, for CTE exposures). The annual dose for the residents who are not recreational anglers based on the CTE exposures is assumed to be zero because the majority of the general population does not consume fish caught from the Peconic River.

The increased lifetime cancer risks from radionuclides for future on-site and current off-site recreational anglers and residents occasionally consuming fish are summarized in Tables 9.1.RME through 9.19.RME for the reasonable maximum exposed individuals. The increased lifetime cancer risks from radionuclides for hypothetical future on-site residents and future on-site recreational anglers that eat on-site fish are greater than 1´ 10^-6. The ILCRs for the future on-site resident recreational anglers (adult, older child, younger child) are 2.2´ 10^-5, 4.3´ 10^-6, 2.2´ 10^-6. For the future on-site resident occasionally consuming fish, the ILCRs are 5.6´ 10^-6, 1.1´ 10^-6, and 1.1´ 10^-6 (adult, older child, younger child, respectively). The increased lifetime cancer risk from radionuclides for off-site anglers and off-site residents who consume locally caught fish is less than that for the future on-site receptors. The highest cancer risk for off-site receptors (8.2´ 10^-6) is for the off-site adult recreational angler consuming 20 lb per year of locally caught fish. The ILCRs for the off-site recreation angler young child and older child and the off-site resident adult, young child, and older child that occasionally consume local caught fish are 8.2´ 10^-7, 1.6´ 10^-6, 2.1´ 10^-7, 4.3´ 10^-7, and 4.3´ 10^-7, respectively. The greatest contributors to these risks are cesium-137 and strontium-90.

For CTE individuals, it was assumed that the adult and older child recreational angler eats eight g/day of locally caught fish (6.4 lb per year) and the young child recreational angler eats half that amount, whereas the occasional CTE resident was considered not to eat any locally caught fish. The cancer risks based on CTE exposures for recreational anglers are summarized in Tables 9.1.CTE through 9.19.CTE. ILCRs for CTE on-site recreational angler adults, younger children, and older children are 1.4´ 10^-7, 4.8´ 10^-7, and 9.6´ 10^-7, respectively. ILCRs for CTE off-site recreational anglers are all less than 1´ 10^-6 (2.0´ 10^-7 for a young child, 4.0´ 10^-7 for an older child, and 6.0´ 10^-7 for an adult). The ILCR for the residents who are not recreational anglers based on the CTE exposures is assumed to be zero since the vast majority of the general population do not consume local caught fish.

The estimated radiation doses and corresponding carcinogenic risks from the fish consumption pathway were low compared to the EPA recommended limits of 15 mrem/year and a risk of 1´ 10^-4 to 1´ 10^-6.

6.4.4 Ingestion of Groundwater

Current off-site residents may be exposed to contaminants in the off-site groundwater if they use private wells as their drinking water and household-use source. The groundwater in the area is classified as Class GA (fresh groundwaters) by the NYSDEC (6 NYCRR Part 701). Although residents in the off-site area near the Peconic River have been offered public water hookups, private wells may still be present. Some private wells are known to be currently used for drinking purposes along North Street. Future on-site residents may also be exposed to contaminants in on-site groundwater in the unlikely event that the site near the Peconic River was ever developed for residential use. Dermal uptake of radionuclides from groundwater does not represent a significant exposure pathway because of the low permeability of radionuclides and the additional shielding from the water.

The annual radiological doses from groundwater for future on-site residents, current trespassers, and current off-site residents are summarized in Tables 9.1.RME through 9.19.RME for the reasonable maximum exposed individuals. The annual radiological dose due to groundwater exposures is less than 0.4 for all receptors, which is well below the 15 mrem/yr EPA dose limit. The RME annual doses for the future on-site resident adult, young child, and older child, and current off-site resident adult, young child, and older child are 0.19, 0.12, 0.12, 0.36, 0.23, and 0.23, respectively. The annual radiological doses from groundwater based on CTE exposure factors are summarized in Tables 9.1.CTE through 9.19.CTE. The CTE annual doses for the future on-site resident adult, young child, and current off-site resident adult, young child, and older child are 0.072, 0.038, 0.038, 0.091, 0.048, 0.048, respectively.

The increased lifetime cancer risk from radionuclides in groundwater for future on-site residents, current trespassers, and current off-site residents are summarized in Tables 9.1.RME through 9.19.RME for the reasonable maximum exposed individuals. The increased lifetime cancer risk due to groundwater exposures is less than 1´ 10^-6 for all receptors except the adult off-site and future on-site residents. The increased lifetime cancer risk from radionuclides in groundwater based on RME exposure factors for the future on-site resident adult, young child, and current off-site resident adult, young child, and older child are 2.6´ 10^-6, 3.3´ 10^-7, 3.3´ 10^-7, 1.6´ 10^-6, 2.1´ 10^-7, and 2.1´ 10^-7, respectively. The increased lifetime cancer risk from radionuclides in groundwater based on CTE exposure factors are summarized in Tables 9.1.CTE through 9.19.CTE. The CTE increased lifetime cancer risk for the future on-site resident adult, young child, and current off-site resident adult, young child, and older child are 2.7´ 10^-7, 9.4´ 10^-8, 9.4´ 10^-8, 2.2´ 10^-7, 7.8´ 10^-8, and 7.8´ 10^-8, respectively.

Though the groundwater data used in this risk assessment are from wells that both characterize and delineate the potential contamination from OU V and the Peconic River, individual wells and well depths may have higher concentrations of some contaminants whereas other wells or depths may have higher concentrations of other contaminants. For example, the low-level VOC plume is located at a depth of approximately 200 feet bls. The data set contains data from monitoring wells located in the shallow aquifer and the upper and lower portions of the deep aquifer. The range of these monitoring well screen intervals compare well with the range of screen intervals of domestic wells reported for the area. The potential uncertainty in the risk assessment concerning the use of the data from an extended area and various well depths is addressed in Section 6.7 of this report.

6.4.5 Ingestion of Soil

Incidental ingestion of soil can expose either future on-site or current off-site residents to contaminants in soils along the Peconic River. Dermal uptake of radionuclides from soil does not represent a significant exposure pathway because of the low permeability of radionuclides. Trespassers may also come into contact with radionuclides in contaminated soil.

The annual radiological doses from soil for future on-site residents, current trespassers, and current off-site residents are summarized in Tables 9.1.RME through 9.19.RME for the reasonable maximum exposed individuals. The annual radiological dose due to incidental ingestion of soil is less than 0.004 for all receptors, which is well below the 15 mrem/yr EPA dose limit. The RME annual doses for the future on-site resident adult, young child, and older child, current trespasser, and current off-site resident adult, young child, and older child are 0.0012, 0.0012, 0.0024, 0.0022, 0.0019, 0.0019, and 0.0037, respectively. The annual radiological doses from incidental ingestion of soil based on CTE exposure factors are summarized in Tables 9.1.CTE through 9.19.CTE. The CTE annual doses for the future on-site resident adult, young child, and older child, current trespasser, and current off-site resident adult, young child, and older child are 0.00043, 0.0043, 0.0086, 0.000016, 0.00081, 0.00081, and 0.0016, respectively.

The increased lifetime cancer risks from radionuclides in soil due to incidental ingestion for future on-site residents, current trespassers, and current off-site residents are summarized in Tables 9.1.RME through 9.19.RME for the reasonable maximum exposed individuals. The increased lifetime cancer risk due to incidental ingestion of soil is less than 5´ 10^-8 for all receptors, which is well below the EPA target range of 1´ 10^-4 to 1´ 10^-6. The increased lifetime cancer risk from incidental ingestion of radionuclides in soil based on RME exposure factors for the future on-site resident adult, young child, and older child, current trespasser, and current off-site resident adult, young child, and older child are 3.1´ 10^-8, 6.2´ 10^-9, 1.3´ 10^-8, 1.1´ 10^-9, 4.8´ 10^-8, 9.6´ 10^-9, and 1.9´ 10^-8, respectively. The increased lifetime cancer risk from incidental ingestion of radionuclides in soil based on CTE exposure factors are summarized in Tables 9.1.CTE through 9.19.CTE. The CTE increased lifetime cancer risk for the future on-site resident adult, young child, and older child, current trespasser, and current off-site resident adult, young child, and older child are 3.3´ 10^-9, 2.2´ 10^-9, 4.5´ 10^-9, 9.3´ 10^-11, 6.3´ 10^-9, 4.2´ 10^-9, and 8.4´ 10^-9, respectively.

The estimated radiation dose and corresponding carcinogenic risk from this pathway were very low compared to the EPA recommended limits of 15 mrem/year and a risk of 1´ 10^-4 to 1´ 10^-6.

6.4.6 Ingestion of Sediment

Incidental ingestion of sediment while engaged in activities in the Peconic River could expose either future on-site or current off-site residents to contaminants in sediment along the Peconic River. Dermal uptake of radionuclides from sediment does not represent a significant exposure pathway because of the low permeability of radionuclides. Trespassers may also come into contact with radionuclides in contaminated sediment while engaged in activities on-site at the Peconic River.

The annual radiological doses from incidental ingestion of sediment for future on-site residents, current trespassers, and current off-site residents are summarized in Tables 9.1.RME through 9.19.RME for the reasonable maximum exposed individuals. The annual radiological dose due to incidental ingestion of sediment is less than 0.8 for all receptors, which is well below the 15 mrem/yr EPA dose limit. The RME annual doses for the future on-site resident adult, young child, and older child, current trespasser, and current off-site resident adult, young child, and older child are 0.14, 0.33, 0.65, 0.73, 0.022, 0.051, and 0.010, respectively. Most of the radiological dose from ingestion of on-site sediment is due to lead-210 with americium-241 being the next highest contributor. Lead-210 was not reported in off-site sediment. Most of the radiological dose from ingestion of off-site sediment is due to americium-241. The annual radiological doses from incidental ingestion of sediment based on CTE exposure factors are summarized in Tables 9.1.CTE through 9.19.CTE. The CTE annual doses for the future on-site resident adult, young child, and older child, current trespasser, and current off-site resident adult, young child, and older child are 0.010, 0.040, 0.081, 0.011, 0.0010, 0.0039, and 0.0078, respectively.

The increased lifetime cancer risk from radionuclides in sediment due to incidental ingestion for future on-site residents, current trespassers, and current off-site residents are summarized in Tables 9.1.RME through 9.19.RME for the reasonable maximum exposed individuals. The increased lifetime cancer risk due to incidental ingestion of soil is less than 2´ 10^-6 for all on-site receptors and less than 1.0´ 10^-7 for all off-site receptors. The increased lifetime cancer risk from incidental ingestion of radionuclides in sediment based on RME exposure factors for the future on-site resident adult, young child, and older child, current trespasser, and current off-site resident adult, young child, and older child are 1.5´ 10^-6, 7.0´ 10^-7, 1.4´ 10^-6, 3.0´ 10^-7, 1.0´ 10^-7, 4.9´ 10^-8, and 9.7´ 10^-8, respectively. The increased lifetime cancer risk from incidental ingestion of radionuclides in sediment based on CTE exposure factors are summarized in Tables 9.1.CTE through 9.19.CTE. The CTE increased lifetime cancer risk for the future on-site resident adult, young child, and older child, current trespasser, and current off-site resident adult, young child, and older child are 3.3´ 10^-8, 8.6´ 10^-8, 1.7´ 10^-7, 2.2´ 10^-8, 2.1´ 10^-9, 5.4´ 10^-9, and 1.1´ 10^-8, respectively.

The estimated radiation dose and corresponding carcinogenic risk from this pathway were well below the EPA recommended limits of 15 mrem/year and were within the risk range of 1´ 10^-4 to 1´ 10^-6.

6.4.7 Inhalation of Airborne Dust and Particulates

Soils and exposed sediment can be inhaled as airborne dusts and particulates. Sediment near the high water marks is almost always dry; thus exposure to this sediment may occur year round. However, exposure to inhalation of most sediment only occurs during periods when the Peconic River is dry; thus, exposure to sediment in intermittent areas was assumed to occur half of the year. The dose and risk assessments for inhalation were calculated using the RESRAD program.

Separate RESRAD estimates were calculated for time spent at the river and time spent at the house because the distance to the source area is different for each of these assumed activity patterns. The RESRAD computer printouts of inputs and outputs are presented in Appendix B.

The annual radiological doses from inhalation of sediment and soil for future on-site residents, current trespassers, and current off-site residents are summarized in Tables 9.1.RME through 9.19.RME for the reasonable maximum exposed individuals. The annual radiological dose due to inhalation of sediment and soil is less than 0.01 for all receptors, which is well below the 15 mrem/yr EPA dose limit. The RME annual doses from inhalation of sediment for the future on-site resident adult, young child, and older child, current trespasser, and current off-site resident adult, young child, and older child are 0.0036, 0.0015, 0.0015, 0.00067, 0.0021, 0.00092, and 0.00092, respectively. Most of the radiological dose from inhalation of sediment is due to americium-241. Lead-210 was not reported in off-site sediment. The RME annual doses from inhalation of riverside soils for the future on-site resident adult, young child, and older child, current trespasser, and current off-site resident adult, young child, and older child are much less than that of sediment and are 1.6´ 10^-7, 7.1´ 10^-8, 7.1´ 10^-8, 3.0´ 10^-8, 2.3´ 10^-7, 1.1´ 10^-7, and 1.1´ 10^-7, respectively. The annual radiological doses from inhalation of sediment and soil based on CTE exposure factors are summarized in Tables 9.1.CTE through 9.19.CTE. The CTE annual doses from sediment for the future on-site resident adult, young child, and older child, current trespasser, and current off-site resident adult, young child, and older child are 0.00074, 0.00032, 0.00032, 0.000028, 0.00096, 0.00042, and 0.00042, respectively, whereas the annual doses from soil are only 2.2´ 10^-7, 5.0´ 10^-8, 5.0´ 10^-8, 4.4´ 10^-9, 2.1´ 10^-7, 9.5´ 10^-8, and 9.5´ 10^-8, respectively.

The increased lifetime cancer risk from inhalation of radionuclides in sediment and soil for future on-site residents, current trespassers, and current off-site residents are summarized in Tables 9.1.RME through 9.19.RME for the reasonable maximum exposed individuals. The increased lifetime cancer risk due to inhalation of sediment and soil is less than 1´ 10^-8 for all receptors. The increased lifetime cancer risk from inhalation of radionuclides in sediment based on RME exposure factors for the future on-site resident adult, young child, and older child, current trespasser, and current off-site resident adult, young child, and older child are 8.0´ 10^-9, 7.8´ 10^-10, 7.8´ 10^-10, 3.4´ 10^-10, 4.6´ 10^-9, 4.6´ 10^-10, and 4.6´ 10^-10, respectively. The increased lifetime cancer risk from inhalation of radionuclides in soil based on RME exposure factors for the future on-site resident adult, young child, and older child, current trespasser, and current off-site resident adult, young child, and older child are 1.9´ 10^-12, 2.3´ 10^-13, 2.3´ 10^-13, 9.7´ 10^-14, 2.6´ 10^-12, 3.6´ 10^-13, and 3.6´ 10^-13, respectively. The increased lifetime cancer risk from incidental ingestion of radionuclides in sediment based on CTE exposure factors are summarized in Tables 9.1.CTE through 9.19.CTE. The CTE increased lifetime cancer risk from inhalation of sediment for the future on-site resident adult, young child, and older child, current trespasser, and current off-site resident adult, young child, and older child are 5.5´ 10^-10, 1.6´ 10^-10, 1.6´ 10^-10, 1.4´ 10^-11, 7.0´ 10^-10, 2.1´ 10^-10, and 2.1´ 10^-10, respectively.

The estimated radiation dose and corresponding carcinogenic risk from this pathway were well below the EPA recommended limits of 15 mrem/year and a risk of 1´ 10^-4 to 1´ 10^-6.

6.4.8 External Gamma Radiation

Both the off-site resident and the future on-site resident can be exposed to gamma radiation from exposed soils and sediment. The dose and risk assessments for external gamma radiation were calculated using the RESRAD program.

Separate RESRAD estimates were calculated for time spent at the river and time spent at the house, because the distance to the source area is different for each of these assumed activity patterns. The RESRAD computer printouts of inputs and outputs are presented in Appendix B.

The annual radiological doses from external gamma radiation from sediment and soil for future on-site residents, current trespassers, and current off-site residents are summarized in Tables 9.1.RME through 9.19.RME for the reasonable maximum exposed individuals. The annual radiological dose due to external gamma radiation is less than 1.0 for all receptors, which is well below the 15 mrem/yr EPA dose limit. The RME annual doses from external radiation from sediment for the future on-site resident adult, young child, and older child, current trespasser, and current off-site resident adult, young child, and older child are 0.27, 0.24, 0.24, 0.15, 0.29, 0.26, and 0.26, respectively. Almost all of the radiological dose from external radiation from exposed sediment is due to cesium-137. The RME annual doses from external radiation from riverside soils for the future on-site resident adult, young child, and older child, current trespasser, and current off-site resident adult, young child, and older child are much less than that from sediment and are 0.0096, 0.0096, 0.0096, 0.0014, 0.013, 0.015, and 0.015, respectively. The annual radiological doses from external radiation from sediment and soil based on CTE exposure factors are summarized in Tables 9.1.CTE through 9.19.CTE. The CTE annual doses from sediment for the future on-site resident adult, young child, and older child, current trespasser, and current off-site resident adult, young child, and older child are 0.22, 0.21, 0.21, 0.0024, 0.23, 0.22, and 0.22, respectively, whereas the annual doses from soil are only 0.013, 0.0069, 0.0069, 0.00020, 0.013, 0.013, and 0.013, respectively.

The increased lifetime cancer risks from external radiation from radionuclides in sediment and soil for future on-site residents, current trespassers, and current off-site residents are summarized in Tables 9.1.RME through 9.19.RME for the reasonable maximum exposed individuals. The increased lifetime cancer risk due to inhalation of sediment and soil is less than 4´ 10^-6 for all receptors. The increased lifetime cancer risk from external radiation from radionuclides in sediment based on RME exposure factors for the future on-site resident adult, young child, and older child, current trespasser, and current off-site resident adult, young child, and older child are 3.2´ 10^-6, 7.9´ 10^-7, 7.9´ 10^-7, 7.8´ 10^-9, 3.8´ 10^-6, 8.8´ 10^-7, and 8.8´ 10^-7, respectively. The increased lifetime cancer risk from external radiation from radionuclides in soil based on RME exposure factors for the future on-site resident adult, young child, and older child, current trespasser, and current off-site resident adult, young child, and older child are 1.3´ 10^-7, 3.4´ 10^-8, 3.4´ 10^-8, 4.9´ 10^-9, 1.8´ 10^-7, 5.2´ 10^-8, and 5.2´ 10^-8, respectively. The increased lifetime cancer risk from external radiation from radionuclides in sediment based on CTE exposure factors are summarized in Tables 9.1.CTE through 9.19.CTE. The CTE increased lifetime cancer risk from external radiation from sediment for the future on-site resident adult, young child, and older child, current trespasser, and current off-site resident adult, young child, and older child are 1.1´ 10^-6, 7.2´ 10^-7, 7.2´ 10^-7, 7.8´ 10^-9, 1.2´ 10^-6, 7.6´ 10^-7, and 7.6´ 10^-7, respectively, whereas the increased lifetime cancer risk from soil is 6.4´ 10^-8, 2.4´ 10^-8, 2.4´ 10^-8, 7.1´ 10^-10, 6.4´ 10^-8, 4.5´ 10^-8, and 4.5´ 10^-87, respectively.

The estimated radiation dose and corresponding carcinogenic risk from this pathway are within the EPA recommended limits of 15 mrem/year and within or below the risk range of 1´ 10^-4 to 1´ 10^-6.

6.4.9 Total Radiological Dose and Risk Assessment

The total dose and total cancer risks associated with radiation exposure from environmental media under current and future land-use scenarios are presented in this section. The total dose is expressed as the Total Effective Dose Equivalent (TEDE), which is the sum of the dose from all sources both internal and external. In this section, the dose and risk from the applicable pathways are summed to present an assessment of the total dose (i.e., TEDE) and risk.

The total radiological dose and risk estimates based on RME exposure factors are presented in Table 9.1.RME through Table 9.19.RME. The total radiological dose and risk estimates based on CTE exposure factors are presented in Table 9.1.CTE through Table 9.19.CTE.

The total dose and radiological risk to current off-site residents who are also recreational anglers and hunters based on RME exposure factors are presented in Table 9.1.RME through Table 9.3.RME. The annual dose is less than the EPA limit of 15 mrem/year (6.0 mrem/year for the adult, 3.3 mrem/year for the young child, and 5.9 mrem/year for the older child). Most of this dose is from the consumption of deer meat with cesium-137. The total increased lifetime cancer risk is just above the EPA target range for the adult (1.2´ 10^-4) but not the young child (1.3´ 10^-5) or older child (2.5´ 10^-5). The total dose and radiological risk based on CTE exposure factors are presented in Table 9.1.CTE through Table 9.3.CTE. The annual dose is less than 1 mrem/year based on CTE exposure factors (0.50 for adults, 0.37 for young children, and 0.45 for older children). The increased lifetime cancer risks are 2.5´ 10^-6 for adults, 1.3´ 10^-6 for young children, and 1.6´ 10^-6 for older children.

The total dose and radiological risk to current off-site recreational anglers/hunters who are not riverside residents based on RME exposure factors are presented in Table 9.4.RME through Table 9.6.RME. The annual dose is less than the EPA limit of 15 mrem/year (5.3 mrem/year for the adult, 2.7 mrem/year for the young child, and 5.3 mrem/year for the older child). Most of this dose is from the consumption of deer meat with cesium-137. The total increased lifetime cancer risk is just above the EPA target range for the adult (1.2´ 10^-4) but not the young child (1.2´ 10^-5) or older child (2.4´ 10^-5). The total dose and radiological risk based on CTE exposure factors are presented in Table 9.4.CTE through Table 9.6.CTE. The annual dose is less than 1 mrem/year based on CTE exposure factors (0.16 for adults, 0.082 for young children, and 0.16 for older children). The increased lifetime cancer risks are 1.1´ 10^-6 for adults, 3.6´ 10^-7 for young children, and 7.2´ 10^-7 for older children

The total dose and radiological risk to current off-site residents who are not recreational anglers and hunters based on RME exposure factors are presented in Table 9.7.RME through Table 9.9.RME. The annual dose is less than the EPA limit of 15 mrem/year (0.79 mrem/year for the adult, 0.71 mrem/year for the young child, and 0.66 mrem/year for the older child). The total increased lifetime cancer risk is within the EPA target range for the adult (7.9´ 10^-6), the young child (1.6´ 10^-6), and the older child (1.6´ 10^-6). The total dose and radiological risk based on CTE exposure factors are presented in Table 9.7.CTE through Table 9.9.CTE. The annual dose is less than 1 mrem/year based on CTE exposure factors (0.33 for adults, 0.29 for young children, and 0.28 for older children). The increased lifetime cancer risks are 1.4´ 10^-6 for adults, 9.0´ 10^-7 for young children, and 8.9´ 10^-7 for older children.

The total radiological dose and increased lifetime cancer risk for trespassers to the BNL site are presented in Table 9.10.RME for RME exposure factors and in Table 9.10.CTE for CTE exposure factors. The total dose based on RME exposure factors is 0.75 mrem/year and the increased lifetime cancer risk is 3.5´ 10^-7. The total dose based on CTE exposure factors is 0.013 mrem/year and the increased lifetime cancer risk is 3.1´ 10^-8. Radionuclides in sediment contribute the most to the radiological dose.

The total dose and radiological risk to future on-site residents who are also recreational anglers and hunters based on RME exposure factors are presented in Table 9.11.RME through Table 9.13.RME. The annual dose is less than the EPA limit of 15 mrem/year (6.6 mrem/year for the adult, 4.0 mrem/year for the young child, and 6.7 mrem/year for the older child). Most of this dose is from the consumption of deer meat with cesium-137. The total increased lifetime cancer risk is just above the EPA target range for the adult (1.4´ 10^-4) but not the young child (1.6´ 10^-5) or older child (2.8´ 10^-5). The total dose and radiological risk based on CTE exposure factors are presented in Table 9.11.CTE through Table 9.13.CTE. The annual dose is less than 1 mrem/year based on CTE exposure factors (0.63 for adults, 0.50 for young children, and 0.61 for older children). The increased lifetime cancer risks are 3.3´ 10^-6 for adults, 1.6´ 10^-6 for young children, and 2.2´ 10^-6 for older children.

The total dose and radiological risk to future on-site recreational anglers/hunters who are not riverside residents based on RME exposure factors are presented in Table 9.14.RME through Table 9.16.RME. The annual dose is less than the EPA limit of 15 mrem/year (6.0 mrem/year for the adult, 3.0 mrem/year for the young child, and 6.0 mrem/year for the older child). Most of this dose is from the consumption of deer meat with cesium-137. The total increased lifetime cancer risk is just above the EPA target range for the adult (1.3´ 10^-4) but not the young child (1.3´ 10^-5) or older child (2.6´ 10^-5). The total dose and radiological risk based on CTE exposure factors are presented in Table 9.14.CTE through Table 9.16.CTE. The annual dose is less than 1 mrem/year based on CTE exposure factors (0.31 for adults, 0.16 for young children, and 0.31 for older children). The increased lifetime cancer risks are 1.9´ 10^-6 for adults, 6.4´ 10^-7 for young children, and 1.3´ 10^-6.

The total dose and radiological risk to future on-site residents who are not recreational anglers and hunters based on RME exposure factors are presented in Table 9.17.RME through Table 91.9.RME. The annual dose is less than the EPA limit of 15 mrem/year (0.89 mrem/year for the adult, 1.3 mrem/year for the young child, and 0.99 mrem/year for the older child). The total increased lifetime cancer risk is within the EPA target range for the adult (1.3´ 10^-5), the young child (3.7´ 10^-6), and the older child (3.0´ 10^-6). The total dose and radiological risk based on CTE exposure factors are presented in Table 9.17.CTE through Table 91.9.CTE. The annual dose is less than 1 mrem/year based on CTE exposure factors (0.32 for adults, 0.34 for young children, and 0.30 for older children). The increased lifetime cancer risks are 1.4´ 10^-6 for adults, 1.0´ 10^-6 for young children, and 9.2´ 10^-7 for older children.

6.5 Total Cancer Risk

Total non-radiological cancer risks were presented in Section 6.3. Total radiological cancer risks were presented in Section 6.4.9. In accordance with EPA guidance in OSWER directive 9200.4-18 and OSWER directive 9200.4-31P, excess cancer risk from both radionuclides and chemical carcinogens should be summed to provide an estimate of the combined risk presented by all carcinogenic contaminants.

The total excess cancer risk based on RME exposure factors for off-site residents who are also recreational anglers and hunters are 3.3´ 10^-4 for the adult, 1.4´ 10^-4 for the young child, and 9.0´ 10^-5 for the older child. The total excess cancer risks for the adult and young child off-site resident angler/hunter exceed the EPA target range of 1´ 10^-4 to 1´ 10^-6. The total excess cancer risk is due about equally to both cesium-137 in deer meat and arsenic and trichloroethene in groundwater used as a drinking water source. The total excess cancer risk based on CTE exposure factors (3.1´ 10^-5 for adults, 4.8´ 10^-5 for young children, and 2.4´ 10^-5 for older children) are all within the EPA target range.

The total excess cancer risk based on RME exposure factors for off-site recreational anglers and hunters who are not riverside residents are 1.4´ 10^-4 for the adult, 2.5´ 10^-5 for the young child, and 3.1´ 10^-5 for the older child. Only the total excess cancer risk for the adult off-site recreational angler/hunter exceeds the EPA target range of 1´ 10^-4 to 1´ 10^-6. The total excess cancer risk is due mostly to cesium-137 in deer meat. The total excess cancer risk based on CTE exposure factors (2.2´ 10^-6 for adults, young children, and older children) are all within the EPA target range.

The total excess cancer risk based on RME exposure factors for off-site residents who are not recreational anglers and hunters are 2.1´ 10^-4 for the adult, 1.3´ 10^-4 for the young child, and 6.2´ 10-⁵ for the older child. The total excess cancer risks for the adult and young child off-site resident exceed the EPA target range of 1´ 10^-4 to 1´ 10^-6. The total excess cancer risk is due to mostly to arsenic and trichloroethene in groundwater used as a drinking water source. The total excess cancer risk based on CTE exposure factors (2.8´ 10^-5 for adults, 34.610^-5 for young children, and 2.2´ 10^-5 for older children) are all within the EPA target range.

The total excess cancer risk for an older child trespasser to the site is 1.2´ 10^-6 based on RME exposure factors and 9.0´ 10^-8 based on CTE exposure factors. All are within or below the EPA target range of 1´ 10^-4 to 1´ 10^-6.

The total excess cancer risk based on RME exposure factors for potential future on-site residents who are also recreational anglers and hunters are 1.2´ 10^-3 for the adult, 5.4´ 10^-4 for the young child, and 4.6´ 10^-4 for the older child. All exceed the EPA target range of 1´ 10^-4 to 1´ 10^-6. The total excess cancer risk is due about mostly to PCBs in fish but is also due to both cesium-137 in deer meat. The total excess cancer risk based on CTE exposure factors (7.6´ 10^-5 for adults, 1.2´ 10^-4 for young children, and 9.6´ 10^-5 for older children). Only the total cancer risk for the young child exceeds the EPA target range, and is due mostly to PCBs in fish.

The total excess cancer risk based on RME exposure factors for potential future on-site recreational anglers and hunters who are not riverside residents are 1.1´ 10^-3 for the adult, 4.9´ 10^-4 for the young child, and 4.4´ 10^-4 for the older child. All exceed the EPA target range of 1´ 10^-4 to 1´ 10^-6. The total excess cancer risk is due about mostly to PCBs in fish but is also due to both cesium-137 in deer meat. The total excess cancer risk based on CTE exposure factors (6.9´ 10^-5 for adults, 1.0´ 10^-4 for young children, and 9.0´ 10^-5 for older children) are all within the EPA target range.

The total excess cancer risk based on RME exposure factors for potential future on-site residents who are not recreational anglers and hunters are 3.2´ 10^-4 for the adult, 2.8´ 10^-4 for the young child, and 1.2´ 10^-4 for the older child. All exceed the EPA target range of 1´ 10^-4 to 1´ 10^-6. The total excess cancer risk is due about mostly to PCBs in fish. The total excess cancer risk based on CTE exposure factors (7.3´ 10^-6 for adults, 1.2´ 10^-5 for young children, and 5.6´ 10^-6 for older children) are all within the EPA target range.

6.6 Risk Assessment Summary

Table 10.1 through Table 10.19 provide a summary of those COPCs and media that contribute most significantly to any potential cancer risks estimated greater than the EPA target range of 1´ 10^-4 to 1´ 10^-6 or non-cancer health hazard quotients greater than 1.0.

For off-site residents who are also recreational anglers and hunters, the total excess cancer risk for adults using groundwater as a drinking water source (1.9´ 10^-4) and for adults consuming significant amounts of locally caught deer meat (1.1´ 10^-4) are outside the EPA target range of 1´ 10^-4 to 1´ 10^-6. Non-cancer hazard quotients above 1.0 are due to mercury in fish for adults (2.5), young children (5.8) and older children (5.0) based on RME exposures, but only for young children (1.7) and older children (1.4) based on CTE exposures. PCB non-cancer hazard quotients are also above 1 from fish consumption by young children (2.1) and older children (1.9) as recreational anglers or in families of recreational anglers based on RME exposures but not CTE exposures. Additionally, arsenic and trichloroethene in groundwater have hazard quotients equal to 1.7 and 2.2 for young children off-site residents based on RME exposures, but are less than one based on CTE exposures. Though the excess cancer risk from consumption of deer meat was in excess of 1´ 10^-4, the total radiological dose was less than the EPA limit of 15 mrem/year.

For off-site recreational anglers/hunters who are not riverside residents, the total excess cancer risk for any individual media is outside the EPA target range for adults consuming significant amounts of locally caught deer meat (1.1´ 10^-4). Non-cancer hazard quotients above 1.0 are due to mercury in fish for adults (2.5), young children (5.8) and older children (2.5) based on RME exposures, but only for young children (1.7) and older children (1.4) based on CTE exposures. PCB non-cancer hazard quotients are also above 1 from fish consumption by young children (2.1) and older children (1.9) as recreational anglers or in families of recreational anglers based on RME exposures but not CTE exposures. Again, though the excess cancer risk from consumption of deer meat was in excess of 1´ 10^-4, the total radiological dose was less than the EPA limit of 15 mrem/year.

For off-site residents who are not recreational anglers or hunters, the total excess cancer risk for any individual media is outside the EPA target range only for adults using groundwater as a drinking water source (1.9´ 10^-4). Non-cancer hazard quotients are greater than one based on RME exposure factors for young children from arsenic and trichloroethene in groundwater when used as a drinking water source (1.7 and 2.2, respectively).

For potential future on-site residents who are also recreational anglers and hunters and for potential future on-site recreational anglers/hunters who are not riverside residents, the total excess cancer risk for adults (1.1´ 10^-3), young children (4.8´ 10^-4), and older children (4.2´ 10^-4) consuming a significant amount of locally caught fish and for adults consuming significant amounts of locally caught deer meat (1.1´ 10^-4) are outside the EPA target range of 1´ 10^-4 to 1´ 10^-6. Non-cancer hazard quotients above 1.0 are due to mercury in fish for adults (3.1), young children (7.2) and older children (6.1) based on RME exposures, but only for young children (1.8) and older children (1.6) based on CTE exposures. PCB non-cancer hazard quotients are also above 1 from fish consumption by adults (58) young children (140) and older children (120) as recreational anglers or in families of recreational anglers based on RME as well as based on CTE exposures (13, 30, and 24, respectively). Though the excess cancer risk from consumption of deer meat was in excess of 1´ 10-4, the total radiological dose was less than the EPA limit of 15 mrem/year.

For off-site residents who are not recreational anglers or hunters but may still consume locally caught fish, the total excess cancer risk for adults (2.7´ 10^-4), young children (2.5´ 10^-4), and older children (1.1´ 10^-4) consuming locally caught fish are outside the EPA target range of 1´ 10^-4 to 1´ 10^-6. Non-cancer hazard quotients above 1.0 are due to mercury in fish for young children (3.7) and older children (1.6) based on RME exposures. PCB non-cancer hazard quotients are also above 1 from fish consumption by adults (15) young children (71) and older children (31). Residents that are not recreational hunters/anglers are assumed to consume no locally caught fish under CTE exposures.

6.7 Uncertainty

Uncertainties in the risk assessment are discussed in this section. Uncertainties may be present in the identification of COPCs, may be associated with the exposure assessment and the toxicity assessment, or may be a result of the risk characterization. In a human health risk assessment, uncertainty relates to both the variability of the available data and to the absence of a value for a parameter of interest (i.e., exposure point concentration, exposure factors).

This risk assessment indicated that the fish consumption, deer meat consumption, and groundwater ingestion pathways contributed the most to any potential cancer risk or health hazard. Section 6.7.2 discusses the uncertainties related to the exposure point concentrations, particularly with regard to these three pathways.

6.7.1 Analytical Data

With regard to analytical data, for example, uncertainty can exist in data collection, data analysis and validation, statistical analysis of the data, and screening of the data. Samples were collected from known and suspected areas of contamination — called "biased sampling" — to delineate the nature and extent of contamination. Although this sampling methodology provided a reasonable estimation of the level of contamination at known or suspected contaminated areas, the possibility exists that the data sets formed by these samples do not accurately represent the level of contamination and instead overestimate the concentrations to which receptors are exposed.

Blank contamination was another source of potential uncertainty with regard to laboratory analysis. Blank contamination can occur during sample collection, sample preparation, or sample analysis, and may result in false positive results in the database. To eliminate this possibility, contaminants detected in samples at concentrations less than five times the concentration detected in the associated blank were treated as non-detects. Common laboratory contaminants (acetone, 2-butanone, and methylene chloride) detected in samples at concentrations less than ten times the concentration detected in the associated blank were also treated as nondetects. This reduced the likelihood of false positive results affecting the quantitative risk assessment; however, it may have eliminated some low-level positive detections in the database.

6.7.2 Exposure Point Concentrations

The statistical analysis of the data introduced some additional uncertainty. Statistical analysis showed that the data exhibited wide ranges of values and variability for certain COPCs. The large variability may be the result of combining samples collected from known areas of contamination (biased samples) and samples collected randomly. While combining samples provides a more accurate representation of the site-wide contamination than either sampling scheme by itself, combining sample types does introduce a high degree of variability into the data set. The exposure point concentrations used in the exposure assessment for the RME receptors are based on 95 percent UCLs of the mean. These provide a conservative estimate of the true average concentration, and, therefore, they tend to overestimate the potential exposure.

Based on EPA recommendations and after analysis of the data sets for their distributional patterns, the 95 percent UCL concentrations were determined based on the distribution. It is, however, worth noting that although a data set may approximate a certain distribution, the data may not actually be distributed as approximated. Thus, the 95 percent UCLs are a source of uncertainty since they assume a given distribution.

Exposure point concentrations, both RME and CTE, are based on average concentrations within an exposure area. Exposure areas may actually be larger (e.g., off-site recreational anglers may fish beyond the North Street to Schultz Road area) or may actually be smaller (e.g., children may play only in the portion of the Peconic River adjacent to their homes and not the entire Area D section). Thus, exposures may be over or underestimated. Conversely, some contaminants (e.g., cesium-137) have somewhat greater concentrations in off-site sediment not included in Area D. Thus, the exposure to cesium-137 in sediment by off-site residents could be underestimated. However, the total risk is not likely to be underestimated because of this since most other contaminants, particularly mercury and PCBs, are higher in the sediment of Area D than in other off-site areas.

Concentrations in Edible Fish Tissue
Estimating the risk from fish consumption was difficult, due to the lack of fish available to sample. Some edible fish tissue data were available for the on-site Area D. This affected both the on-site fish tissue and off-site fish tissue risk estimates. The on-site fish tissue data were almost entirely whole body (bones and viscera included) samples. Whole body samples tend to have significantly higher concentrations of organic compounds (e.g., PCBs) than do edible fish tissue samples for the same fish. Thus, since the on-site receptors’ risk was based on whole-body samples, the risk estimate is over-conservative, based on consuming edible tissues from those fish. However, most of these fish were small. Concentrations in comparable tissues of larger, edible-sized fish, if available, would likely have been greater. Conversely, whole body concentrations may underestimate the concentrations of other non-organic contaminants, such as mercury, which may be at higher concentrations in edible tissues. The off-site fish tissue data set included edible fish tissue data from the Schultz Road area up to, and including, the on-site Area D edible fish tissue data. These data under-represented Area D on-site fish from above the gauging station. Since concentrations of contaminants were generally greater above the gauging station, the exposure concentrations used to represent the edible fish tissue concentrations may have been underestimated. Additionally, fish data used in this risk assessment represented only one year (off-site receptor data set) or only a few years (on-site receptor data set) of data. Concentrations in the future or in larger fish, if present, may be different than those currently measured.

Mercury detected in fish tissue was assumed to be entirely methylmercury. Methylmercury is more toxic than inorganic mercury, so, though most mercury in fish is reported to occur as methylmercury (EPA 2000b), the risk is still likely to be overestimated to some extent.

The off-site fish tissue data set included edible fish tissue data from the Schultz road area up to, and including, the on-site Area D below the gauging station, all of which were collected during one period in 2001. These data under-represent Area D on-site fish from above the gauging station. Since the concentrations of contaminants, particularly PCBs, were generally greater above the gauging station, the exposure concentrations used to represent the edible fish tissue concentrations may have been underestimated. The non-cancer health hazard to off-site recreational anglers from the consumption of fish were reported as 3.4 to 7.9 and the non-radiological cancer risks were reported as 6.4´ 10^-6 to 1.5´ 10^-5. If the edible fish tissue concentrations were assumed to be the same as the measured whole body fish tissue concentrations for PCBs from the fish that were collected in 1997 from on-site Area D, the non-cancer health hazards to off-site recreational anglers could be almost 2.5 times greater (8.3 to 17) and the non-radiological cancer risks to off-site recreational anglers could be almost 10 times greater (5.7´ 10^-5 to 1.4´ 10^-4 for non-radiological cancer risks).

Exposure Point Concentrations for Groundwater
Exposure point concentrations for groundwater to which off-site receptors could be exposed were based on average concentrations in the groundwater near the Peconic River and the BNL boundary as well as off-site within the delineated contaminant plumes (e.g., for tritium and volatile organic compounds) and represented shallow and deeper groundwater. Residential wells placed at particular depths and locations could result in exposure concentrations greater than the 95 percent UCLs used in the risk assessment. Thus, risks to these individuals could be underestimated. Conversely, though such wells may be higher in exposures to some contaminants, they may also be lower in other contaminants.

One residential well that had been sampled near the Peconic River did show trichloroethene concentrations (as well as other VOCs) in excess of the exposure point concentrations used in this risk assessment. The table below illustrates some of the VOC concentrations measured in that residential well during the period 1985 to 1996. It should be noted that this residence had been subsequently provided a filter for removal of contaminants and that the residence has been hooked-up to the public water supply and no longer uses the well as its household drinking water source.

Select Off-Site Residential Well Data near the Peconic River and North Street

Date	1,1-Dichloroethane (µg/L)	Trichloroethene (µg/L)	1,1-Dichloroethene (µg/L)
2/25/85	3	5	3
4/11/86	3	6	2
10/22/87	2	9	<1
2/18/88	2	7	<1
9/20/20	2	3	<1
12/18/91	7	7	2
6/25/92	7	6	1
3/19/94	3	9	0.7
5/21/96	3	8	0.7

To address this uncertainty, the individual monitoring wells were evaluated separately for the main COPCs in groundwater: arsenic, manganese, trichloroethene, and tritium. The average and maximum concentrations for each of the monitoring well locations are presented in the following table.

Summary of Individual Monitoring Well Data for Main COPCs

Well ID	Screen Interval (feet bls)	Trichloroethene		Arsenic		Manganese		Tritium
Well ID	Screen Interval (feet bls)	Ave. (µg/L)	Max. (µg/L)	Ave. (µg/L)	Max. (µg/L)	Ave. (µg/L)	Max. (µg/L)	Ave. (pCi/L)	Max. (pCi/L)
000-122	240-260	ND	ND	1.43	2.1	55.4	63.6	415	1190
000-123	150-170	0.26	0.42	4.4	7.2	764	987	362	1390
049-05	90-100	ND	ND	1.03	1.4	986	2850	225	470
049-06	175-185	0.59	1.71	1.03	1.4	1.9	12.1	458	1340
050-01	205-225	7.4	18	ND	ND	316	654	458	1039
050-02	140-160	ND	ND	14.4	21	1471	2720	2206	3320
061-04	90-100	ND	ND	1.3	1.4	1384	3070	748	1660
061-05	195-205	17.5	25.6	1.5	2.3	43	56.8	1242	2186

The risk assessment presented reasonable maximum exposure hazard quotients for the adult off-site resident from ingestion of groundwater as 1.6 (0.57 from arsenic, 0.30 from manganese, and 0.70 from trichloroethene), the non-radiological cancer risk as 1.9´ 10^-4 (1.1´ 10^-4 from arsenic and 7.8´ 10^-5 from trichloroethene, and the radiological cancer risk as 1.6´ 10^-6 1.3´ 10^-6 from tritium) based on the 95 percent UCL concentrations for the entire data set. These hazards and risks resulted from using the 95 percent UCL of the mean concentrations of 6.2 m g/L arsenic, 1442 m g/L manganese, 7.4 m g/L trichloroethene, and 1249 pCi/L tritium. The data on some individual monitoring wells presented in the following paragraphs illustrate a potential range in the uncertainty, though the uncertainty is relatively small.

The highest trichloroethene concentrations were located in a monitoring well (061-05) on-site but near the Peconic River and North Street (screened in the lower deep aquifer), with a maximum concentration of 25.6 m g/L and a 95 percent UCL of 19.7 m g/L. This monitoring well is located near to the residential well location discussed previously and at about the same depth in the aquifer, and has higher TCE concentrations than the residential well. This monitoring well also had elevated tritium levels (95 percent UCL of 1461 pCi/L) but relatively low arsenic and manganese levels (95 percent UCLs of 1.74 m g/L and 48 m g/L, respectively). The reasonable maximum exposure hazard quotients for the adult resident from ingesting groundwater from this area of the aquifer is 2.1 (0.16 from arsenic, 0.0094 from manganese, and 1.8 from trichloroethene), the non-radiological cancer risk as 1.2´ 10^-4 (3.1´ 10^-5 from arsenic and 9.3´ 10^-5 from trichloroethene), and the radiological cancer risk as 2.3´ 10^-6 (1.6´ 10^-6 from tritium). The total hazard quotient is only about 30 percent higher than that presented in the report, whereas the total cancer risk is almost 40 percent less.

A monitoring well (061-04) at the same location but screened in the upper deep aquifer reported the maximum manganese concentrations, with a maximum of 3070 m g/L and a 95 percent UCL of 1768 m g/L, as well as elevated tritium levels (95 percent UCL of 1005 pCi/L), but arsenic was relatively low (95 percent UCL of 1.55 m g/L) and trichloroethene was not detected. The reasonable maximum exposure hazard quotients for the adult resident from ingesting groundwater from this area of the aquifer is 0.58 (0.14 from arsenic and 0.35 from manganese), the non-radiological cancer risk as 2.9´ 10^-5 (2.7´ 10^-5 from arsenic), and the radiological cancer risk as 1.8´ 10^-6 (1.1´ 10^-6 from tritium). The total hazard quotient and cancer risk are much lower than that presented in the report using all the monitoring well data.

The maximum concentrations of arsenic (maximum of 21 m g/L and 95 percent UCL of 17.7 m g/L) and tritium (maximum of 3320 pCi/L and 95 percent UCL of 2546 pCi/L) were reported in a monitoring well (050-02) on the BNL site near the BNL boundary and the Peconic River and screened in the upper deep aquifer. This well also had elevated manganese concentrations (maximum of 2720 m g/L and 95 percent UCL of 2012 m g/L) but trichloroethene was not detected. The reasonable maximum exposure hazard quotients for the adult resident from ingesting groundwater from these area of the aquifer is 2.1 (0.16 from arsenic and 0.39 from manganese), the non-radiological cancer risk as 3.1´ 10^-4 (almost entirely from arsenic), and the radiological cancer risk as 3.4´ 10^-6 (2.7´ 10^-6 from tritium). The total hazard quotient is about 30 percent higher than that presented in the report and the cancer risk is about 2 times that presented in the report.

Another well (000-122) screened in the lower deep aquifer near the LIE downgradient of the Peconic River and the STP also reported elevated trichloroethene (maximum of 10.7 m g/L and 95 percent UCL of 8.8 m g/L) and tritium levels (maximum of 1190 pCi/L and 95 percent UCL of 747 pCi/L) but relatively low arsenic (95 percent UCL of 1.66 m g/L) and manganese levels (95 percent UCL of 61.2 m g/L). The reasonable maximum exposure hazard quotients for the adult resident from ingesting groundwater from this area of the aquifer is 1.1 (0.15 from arsenic, 0.012 from manganese, and 0.80 from trichloroethene), the non-radiological cancer risk as 7.2´ 10^-5 (2.9´ 10^-5 from arsenic and 4.1´ 10^-5 from trichloroethene), and the radiological cancer risk as 1.5´ 10^-6 (7.9´ 10^-7 from tritium). The total hazard quotient is about 30 percent less than that presented in the report, whereas the total cancer risk is less than half the value presented in the report.

In summary, based on the data available, an off-site resident using a residential well as its drinking water supply and for its household use may be exposed to concentrations of COPCs that represent a potential health hazard or cancer risk different than that presented in the risk assessment. The hazard or risk may be greater or less than that presented. Based on an evaluation of individual monitoring well data, with consideration of previous residential well data, the potential hazard may be up to 30 percent higher or the risk may be as much as 2 times that presented in the risk assessment. Public water hookups within the area and a program of continued monitoring, as described within the OU V Record of Decision for the STP, have been implemented to address these groundwater contaminants and potential risks or health hazards.

Exposure Point Concentrations for Deer Meat
The cesium-137 concentrations in deer meat data used in the risk assessment were not necessarily attributable to Peconic River contaminants. Since the deer data used in this risk assessment were from the entire BNL site as well as within the vicinity of the BNL site and the Peconic River area, the measured cesium-137 activities may be due to other sources besides the Peconic River area. Based on cesium-137 data obtained from vegetation within the Peconic River area, a conservative estimate of the tissue levels can be made based on ingestion of only Peconic River vegetation.

To estimate the potential concentration of cesium-137 in deer meat, the following equation and assumptions were used (Bechtel Jacobs 1999):

where:
C_deer is the concentration in tissue of the deer in wet weight
BTF is the biotransfer factor (d/kg on a wet weight basis)
C_food is the concentration of the contaminant in the food of the deer (dry weight basis)
IR_food is the ingestion rate of the deer (kg/d dry weight)
C_sed is the concentration of the contaminant in the sediment (dry weight basis)
IR_sed is the incidental ingestion rate of the soil/sediment (dry weight basis)
f_p is the fraction of the year that the animal spends on the contaminated site
f_a is the fraction of food on the site that is contaminated

The following values are estimates that were used in the equation to account for site-specific condition. The values are conservative, as will be discussed. The BTF of 0.23 d/kg is taken from an International Atomic Energy Agency report (IAEA 1994) and is based on an experimental cesium-137 uptake in goats. This value is recommended for deer by guidance from the Risk Assessment Information System at Oak Ridge National Laboratory. For C_food the value used was 3.5 pCi/g. This was the average concentration of cesium-137 observed in roots of tussock sedge, which was the plant matter with the greatest concentrations of cesium-137 observed in the Peconic River sampling campaign. This species represents only a small fraction of plant material in the area, but we have assumed that a deer eats only the roots of this sedge, thereby consuming plants, and plant parts, with the highest observed concentrations. The quantity of food eaten by a deer (IR_food) was based on the consumption rates for dairy goats, and was assumed to be 1.3 kg/d. Beyer et al. (1994) report that the amount of soil ingested by deer represents about two percent of its diet. This is equal to 0.026 kg/d. Though this is a small amount relative to the amount of plant matter consumed, it is incorporated in the model due to the higher concentrations measured in sediment. The average surface sediment concentration is about 8 pCi/g for both on-site and off-site Area D. Surface water consumption could also be incorporated into the model. However, cesium-137 was not detected in surface water of the Peconic River

Given that a deer’s range is approximately one mile in radius or greater depending on food and habitat availability, it is doubtful that a deer would remain in areas of greatest cesium-137 concentrations for 100 percent of the time. Nevertheless the values for f_p and f_a are conservatively set to 1. Based on these values, a cesium-137 concentration in deer meat of 1.11 pCi/g wet weight was determined.

Since this model used conservative assumptions (e.g., deer obtain the food only from contaminated on-site tussock sedge roots), it could be expected that the model would overestimate the actual concentrations. However, the modeled concentration is less than the 2.2 pCi/g average concentration for the deer data used in the risk assessment. Thus, it is possible that the deer have bioaccumulated cesium-137 from other on-site sources. Other on-site sources are being addressed in remedial actions for other operable units (particularly Operable Unit I). Furthermore, for RME exposure, the 95 percent UCL of 4.0 pCi/g was used in the risk calculations and could be over-conservative based on the modeled concentrations.

Exposure Point Concentrations for Riverside Soil
In general, soil samples have not been collected beyond the high water mark of the river up to the location or potential location of residential homes that would be representative of soil exposures to off-site or on-site riverside residents. Several surface soil samples were collected in 2001 near the Peconic River in areas that may have received sediment removed from the river. These samples were collected near the STP discharge, near gauging station HM in Area A, and near gauging station HQ in Area D. Since these soil samples were collected from areas where it is suspected that sediment from the river may have been removed and placed on the nearby soil during construction activities related to the gauging stations, they were expected to be conservative estimates of average soil concentrations near the Peconic River. No other data were available for soils, and not sediment, near the river. This lack of actual soil data away from the river and nearer to actual or potential residences was a source of uncertainty. In order to address this uncertainty, in November 2002, several soil samples were collected along three transects extending from the high water mark of the river to the nearest residences. Cesium-137 was only detected in six of the fifteen samples, with the highest detected activity at 8 pCi/g. These were less than that reported for the soils near the gauging stations in Area A and Area D. Thus, though the use of the small soil data set consisting of samples from near the gauging stations is a source of uncertainty, evidence suggests that this is conservative, at least for the external gamma radiation pathway.

6.7.3 Exposure Factors

Uncertainties related to the conservative aspect of the risk analysis process and methodologies are especially apparent in the exposure assessment. The EPA model for conducting human health risk assessments presently requires the use of point estimates for all parameters (e.g., chemical concentration, body weight, length of residence) to establish risk estimates for exposure scenarios. Single-point estimates, however, do not demonstrate the similarity or variability of the data. Therefore, uncertainty analysis is limited to qualitative statements about the confidence placed in critical data or default input parameters used in the exposure assessment used to establish the baseline human health risk assessment.

EPA default values for many of the RME parameters — used for ingestion rates of environmental media, exposure duration, and frequency of events — tends to overestimate exposure dosages in the current and future land-use scenarios. In particular for this risk assessment, the uncertainty lies in the fact that fish ingestion rates for the RME recreational anglers are based on surveys of a large number of recreational anglers. The conditions of the upstream portion of the Peconic River (e.g., inaccessibility, shallow water levels, low flow, large periods of dryness, small number and size of most fish) are not preferred fishing habitats for typical recreational anglers. Thus, the use of exposure factors for typical recreational anglers may not be appropriate for recreational anglers in the upstream sections of the Peconic River.

No data were available that measured concentrations of the respirable fraction of airborne particulates at the BNL site. Therefore, using meteorological data collected in a study of outdoor air particulate concentrations in Suffolk County (EPA 1995a), an upper-bound soil particulate concentration (i.e., 30 m g/m³) was assumed. Considering the extensive vegetation that covers most of the area, the particulate concentration used in the inhalation exposure algorithm probably overestimates the amount of respirable particulate materials generated from soils and sediment.

In exposure pathways that estimate uptake by ingestion, it was assumed that 100 percent of the ingested COPCs were absorbed. This assumption may be valid for organic, lipophilic COPCs, but this assumption overestimates intake of most inorganic COPCs. Thus, for metals, the fraction of inorganic contaminants actually absorbed by ingestion is likely to be overestimated in the CDI dose rate uptake of COPCs in all environmental media. As demonstrated in many animal studies and in limited human studies measuring bioavailability of metals after ingestion, less than 10 percent of most metals, even in soluble form, are absorbed from the alimentary tract into the body. This one assumption may overestimate ingested metals intake in all media by an order of magnitude.

Dermal uptake of COPCs by direct dermal contact to soil, sediment, or water is an exposure pathway with inherent uncertainty. Dermal uptake is directly proportional to the length of time for each exposure event. While dermal absorption coefficients for estimating absorbed doses from direct skin contact with water are available or can be calculated (EPA 2001), for some contaminants, metals —including those dissolved in water — are generally poorly absorbed through skin contact.

Dermal uptake from soil/sediment is even more uncertain. Quantitative exposure assessment of COPCs in soil/sediment by direct dermal contact is limited to the contaminants for which absorption factors were available. Dermal uptake of other COPCs is underestimated in these dermal exposure pathways. However, uptake of metals by dermal exposure to soil/sediment is considered a minor contributing pathway to the total estimated dosage of metals in contaminated media. Transfer of metals from soil to skin as an absorbed dose appears to be on the order of 0.1 to 1.0 percent of the available dose in soil (EPA 1995a).

6.7.4 Uncertainties in Toxicity Assessment

Toxicity assessment relies upon the use of toxicity values (carcinogenic SF, non-carcinogenic RfDs, or RfCs) developed by the EPA to evaluate potential chronic toxicity of COPCs. These toxicity values may be estimated from human data, but the process is largely dependent upon laboratory animal data generated from a variety of toxicology and safety testing studies conducted on contaminants.

Toxicity values are not available for all COPCs. Therefore, health risks/hazards cannot be quantitatively assessed for all contaminants and the total risk/hazard for the site may be underestimated in such circumstances.

The carcinogen toxicity values, SFs, are derived from cancer bioassay or epidemiologic dose-response data to estimate carcinogenic risk at contaminant concentrations that may be several orders of magnitude lower that the given dose or estimated exposure observed in the studies that form the basis of the assessment. Thus, extrapolations are made in projecting potential effects at low doses from data on effects at high doses; all these extrapolations add to the uncertainty. A number of uncertainties are associated with this methodology:

The extrapolation of observed carcinogenic effects at high doses used in animal cancer studies to possible cancer effects at substantially lower doses is based on the hypothesis that there is no threshold dose for carcinogens. No experimental evidence is available to support this thesis.

The extrapolation of carcinogenic and non-carcinogenic effects in animals to effects in humans may not be appropriate for all contaminants, particularly if there are large species differences in metabolism of the contaminant.

While the EPA recommends standard weight-of-evidence descriptors for carcinogens, the cancer risk algorithm does not utilize this weight-of-evidence and sums all carcinogen risks equally, whether a COPC is a known human carcinogen or only a suspect carcinogen.

Each of these three uncertainty factors tends to overestimate cancer risk. There are also questions concerning the summation of cancer risks when different contaminants have specific target organs or induce quite different neoplastic disease states.

The carcinogenic information on trichloroethene provides a range of slope factors: 0.40 to 0.02 (mg/kg-day)^-1. A range is presented as opposed to a single number due to the risk factors that can modify the effects of TCE in different populations. Because the modifying effect of most risk factors cannot be quantified, EPA recommends using the upper end of the slope factor range for susceptible populations having risk factors for TCE-induced cancer. The upper end slope factor was used in this risk assessment to assure that risk to susceptible individuals is not underestimated. However, risks to the general exposed population may be overestimated.

Toxicity values derived to estimate chronic dosages that may induce non-cancer adverse effects also have a number of limitations. Unlike cancer risk assessment, by convention non-cancer adverse effects are assumed to occur in a dose-response manner only after a threshold dose has been exceeded. This is the basis for the use of the RfD or RfC in estimating the HI. If this ratio is greater than 1.0, such exposures may be considered hazardous. The HI can only be used to qualitatively rank the possibility of adverse non-cancer effects occurring. The following uncertainties are present with the use of the hazard index to describe non-cancer health hazards:

RfDs are derived from NOAEL or LOAEL dose rates determined from animal studies or human exposure investigations. Depending on the quality of the available data, the NOAEL or LOAEL is divided by an uncertainty factor ranging from 1 to 10,000. Large uncertainty factors used in extrapolating animal effects to human effects may over-estimate non-cancer hazards.

The HI approach assumes that all non-cancer adverse effects to the same organ or systems are additive. While this approach may be sound for assessing a series of contaminants that have similar modes of action and act on the same target organ, it may not be appropriate when there are different modes of action.

Summation of HIs to calculate a total HI for an exposure scenario can generate a very large number. The HI is a ratio of estimated exposure compared to a "safe" exposure dose. A health hazard is indicated if this ratio exceeds one. The magnitude of a calculated HI greater than one has little bearing on the potential severity of adverse effects.

A number of factors contributed to uncertainties in this risk characterization. These uncertainties are attributable to the risk characterization procedure itself and to several site-specific factors.

Quantitative risk characterization is largely dependent upon laboratory-derived animal toxicity values (carcinogenic slope factors, non-carcinogenic RfDs, and RfCs) for the contaminants of potential concern. Toxicity values are not available for all COPCs; therefore, risks/hazards cannot be quantitatively characterized for these contaminants and the total calculated risk/hazard for the site may be underestimated. Additionally, toxicity values derived from animal studies are given the same weight as toxicity values derived from human data.

COPCs with different carcinogenic weights of evidence are summed in this risk characterization. The carcinogenic risk equation for multiple substances sums all carcinogens equally, giving as much weight to Group B1 or B2 carcinogens as to Group A carcinogens. This tends to overestimate calculated carcinogenic risks.

The summation of carcinogenic risks from individual contaminants may also lead to some uncertainty. Antagonistic or synergistic effects are not accounted for in this characterization, resulting in potential over- or under-estimations of carcinogenic risk.

The addition of hazard indices also has several limitations. As described in the toxicity assessment section of this report, the level of potential impact does not increase linearly as the RfD/RfC is approached or exceeded because the RfDs/RfCs do not have equal accuracy or precision and are not based on the same severity of effect. Additionally, HQs are combined for substances with RfDs/RfCs based on critical effects of varying toxicological significance. Also, RfDs and RfCs of varying levels of confidence, which include different uncertainty factors and modifying factors (e.g., extrapolation from animal data to humans, extrapolation from LOAELs to NOAELs, and extrapolation from one exposure duration to another), are combined.

Another limitation with the hazard index approach is the assumption that dose additivity is applied to all COPCs for all exposure media and pathways. This assumption implies that all compounds induce the same effect by the same mechanism of action. This is clearly not the case for the COPCs in the area. Consequently, the application of the HI equation to a number of COPCs that are not expected to induce the same type of effects and do not act by the same mechanism will overestimate the potential for adverse effects.

7.0 Summary and Recommendations

This human health risk assessment was conducted in order to reassess the human health risks related to contamination in the Peconic River. The reassessment was based on the additional chemical and radiological analyses that have been performed since the original human health risk assessment was presented as part of the remedial investigation report. The scope of this risk assessment was developed following review by, and discussions with, EPA, NYSDEC, NYSDOH, and SCDHS personnel.

This risk assessment evaluated potential contaminant exposures to residents living along the Peconic River downstream of the BNL site and potential future residents that might live on-site along the Peconic River. These residents could be exposed to contaminants in sediment and surface waters of the Peconic River, contaminants in groundwater in the vicinity of the Peconic River that could be used as a household water source, contaminants in soils alongside the Peconic River, contaminants in fish that may have accumulated contaminants from the surface water and sediment of the Peconic River, and contaminants in deer that may have accumulated contaminants from foraging in the area of OU V and the Peconic River. Besides the future residents that may be exposed to on-site contaminants, trespassers to the site may be currently exposed to on-site contaminants. Additionally, recreational anglers and hunters, though not necessarily residents living alongside the Peconic River, may be exposed to contaminants while fishing or hunting at or near the Peconic River.

Constituents of potential concern (COPC) were identified in some or all of the environmental media investigated. These included inorganics (arsenic, cadmium, chromium, copper, cyanide, iron, manganese, mercury, and thallium), volatile organic compounds (1,1-dichloroethene, 1,2-dichloroethane, ammonia, chloroform, tetrachloroethene, and trichloroethene), pesticides (DDD, DDE, DDT and alpha-chlordane), PCBs (Aroclor-1242, Aroclor-1254 and Aroclor-1260), PAHs (benzo(a)pyrene and benzo(b)fluoranthene), and radionuclides (americium-241, cesium-137, cobalt-60, lead-210, plutonium-238, plutonium-239/240, strontium-90, tritium, uranium-233/234, uranium-235, and uranium-238).

Total excess cancer risks to current off-site adult and young child residents, current off-site adult and young child resident angler/hunters, and current off-site adult non-resident angler/hunters were greater than the EPA target range of 1´ 10^-4 to 1´ 10^-6. This is due to arsenic and trichloroethene in groundwater as well as cesium-137 in deer meat. Total excess cancer risks for the current off-site older child residents, current off-site older child resident angler/hunters, and current off-site older and younger child non-resident angler/hunters were within the EPA target range, as was the total excess cancer risk for current trespassers to on-site. Non-cancer health hazard quotients exceeded 1.0 for these current recreational angler adults and children based on the assumed reasonable maximum exposure (RME) factors due to mercury in edible fish tissue and for these current recreational angler children due to PCBs. Non-cancer health hazard quotients exceeded 1.0 for current off-site resident children that consumed locally caught fish, due to mercury as well as PCBs for the younger children. The hazard quotient for these young children assuming RME exposures based on arsenic in groundwater in the off-site area is 1.7, and based on trichloroethene in groundwater in the off-site area is 2.2. Based on CTE exposures these are less than one. Arsenic in groundwater is likely due to naturally occurring arsenic in the soil, and it is not thought to be site-related. Because the concentrations of arsenic in groundwater are below the groundwater standard of 25 m g/L, remedial action objectives that address arsenic in groundwater are not warranted. The elevated concentrations in some of the groundwater samples are likely due to an inappropriately high level of suspended soil particulates in some samples and the naturally-occurring concentrations of arsenic in the soil. The groundwater in the area is classified as Class GA (fresh groundwaters) by the NYSDEC (6 NYCRR Part 701). To assure future safe drinking water, residents along the river in this area have been provided connection to the public water supply, and groundwater monitoring will continue. The groundwater standard for trichloroethene is 5 m g/L. Concentrations above the groundwater standard have been found in several samples as well as in samples of private wells and a trichloroethene plume has been defined in the area. Residents within this area have been provided access to the public water system and BNL continues to monitor the groundwater quality in the area.

Though this risk assessment evaluated exposure to cesium-137 through the consumption of potentially contaminated deer meat, it is likely that the elevated concentrations detected in deer are related more to other BNL on-site sources than to the Peconic River or OU V sources. Other sources that could result in cesium-137 in deer are being, or have been, remediated as part of Operable Unit I through the remediation of contaminated soils, which is designed to reduce the deer contamination. BNL also has an active monitoring program in place through which cesium-137 levels in deer are measured both on site and in off site areas. No further remedial action objectives that address deer contamination are recommended under OU V based on the results of this risk assessment.

It should be noted that some degree of uncertainty is inherent in the risk assessment process. There are many potential sources of uncertainty, and upper percentile estimates or safety factors are often used to assure that potential risks or health hazards are not under-estimated. One significant source of uncertainty is in the exposure factors used to try to estimate exposure to the RME individuals. The use of EPA default values for many of the RME parameters – used for ingestion rates of environmental media, exposure duration, and frequency of events – tends to overestimate exposure dosages in the current and future land-use scenarios. In particular, fish ingestion rates for the RME recreational anglers are based on surveys of a large amount of recreational anglers. The conditions of much of the upstream portion of the Peconic River (e.g., inaccessibility, shallow water levels, low flow, large periods of dryness, small number and size of most fish) are not preferred fishing conditions for typical recreational anglers. Thus, the use of exposure factors for typical recreational anglers may not be appropriate for recreational anglers in the upstream sections of the Peconic River.

A significant source of uncertainty in the risk assessment is the consumption rates for this area of the Peconic River. Conditions in the area (low water depth, frequent periods when no water is present, low dissolved oxygen levels, low water flow, inaccessibility of most areas, limited open water areas) may both limit the productivity of the river and reduce the use of the river by recreational anglers. Both of these may result in much lower consumption rates than those upon which the risk assessment is based. To reduce uncertainty about the fish consumption pathway two additional evaluations are recommended: 1) a prediction of the potential range of future water levels in the Peconic River based on historic water flow and water table levels; 2) a characterization of Peconic River fish habitats between the BNL Sewage Treatment Plant and Schultz Road followed by a prediction of potential future fish biomass within this section of the river for low, high and mid water levels. The water level in the upstream sections of the Peconic River is controlled by the water table level and the volume of treated effluent released into the river from the BNL Sewage Treatment Plant. Over the past fifty years there has been considerable variability in the water level of the onsite and immediate offsite sections of the river. This variability has caused uncertainty in the fish carrying capacity and hence the appropriate rates of consumption of fish by humans. To address this uncertainty BNL has initiated an assessment of fish habitat and biomass carrying capacity of the upstream section of the Peconic River between the Sewage Treatment Plant and Schultz Road. The results of this study will be placed in the Administrative Record as an attachment to the revised risk assessment. A second activity is to document historic flow rates in the Peconic River, which will be used to predict the future range of water levels. This document will also be placed in the Administrative Record.

Total cancer risks to future on-site residents who occasionally consume locally caught fish, future on-site resident angler/hunters, and future non-resident angler/hunters in on-site areas were all above the EPA target range of 1´ 10^-4 to 1´ 10^-6. Potential cancer risks are due to PCBs in fish as measured in whole-body fish samples (adequate edible fish tissue samples were not available for the on-site area) and cesium-137 in deer meat. Non-cancer health hazard quotients exceeded 1.0 for these same future on-site receptors due to mercury and PCBs in fish as measured in whole-body fish samples. Cancer risks were within the EPA target range of 1´ 10^-4 to 1´ 10^-6 and non-cancer health hazard quotients were below 1.0 for future on-site residents that do not consume locally caught fish or deer.

Recommendations for additional actions include:

Evaluate the appropriateness of the fish consumption exposure factors for the on-site and off-site upstream portions of the Peconic River by evaluating the productivity of the river.
Evaluate the appropriateness of the site-specific fish consumption patterns.
Continue monitoring fish.
Continue monitoring deer.
Develop Remedial Action Objectives to address contaminated fish.
Evaluate potential future water levels and their frequency in the upper section of the Peconic River as a function of historic flow rates and water levels.
Evaluate potential fish biomass that the upper section of the Peconic River could support under low, high and mid water levels.

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