Risk Assessment Report for the Sheboygan River
Total Page：16
File Type：pdf, Size：1020Kb
RISK ASSESSMENT FOR THE SHEBOYGAN RIVER, SHEBOYGAN COUNTY, WISCONSIN EPA Region 6 Records Ctr. 224694 RISK ASSESSMENT FOR THE SHEBOYGAN RIVER, SHEBOYGAN COUNTY, WISCONSIN •i J -j "1 Prepared for ^ Teciunseh Products Company I Sheboygan Falls, Wisconsin .^ Prepared by i ENVIRON Corporation *: Princeton, New Jersey ~.J August 1995 CONTENTS Page I. EXECUTIVE SUMMARY 1 II. INTRODUCTION 9 A. Objective 9 B. Background 9 C. Monte Carlo Simulation 12 HI. HAZARD IDENTTFICATION 13 A. Analytical Information Regarding the Sheboygan River Site 13 n 1. Fish 13 2. Floodplain Soil 15 B. Characteristics of PCBs 15 _^ IV. TOXICITY ASSESSMENT 21 A. General Considerations 21 "1 B. Carcinogenic (Non-threshold Toricity) 23 - i 1. Differential Carcinogenic Potency Estimates Based on Chase et al. (1989) 25 ~1 2. Revisions to the Chase et al. Approach Based on Recently i Proposed Scaling Factor 28 ~~ 3. Revisions to the Chase et al. Approach Based on Reevaluation "" I of the Liver Histopathology 29 - i 4. Revision to the Chase et al. Approach Based on Consideration of Data from All Appropriate Bioassays 30 V. ESTIMATE OF HUMAN EXPOSURE 32 A. Receptors and Exposure Routes 32 ^_ 1. Recreational Fishing 32 J 2. Floodplain Soils 36 B. Intake Calculations 36 C. Exposure Assumptions 43 "^ \. Generic Assumptions 43 2. Recreational Fishing 46 3. Flood Plain Soil 51 VI. RISK CHARACTERIZATION 56 A. Risk Calculations 56 B. Potential Cancer Risks 56 ENVIRON CONTENTS (continued) Page VII. UNCERTAINTY 60 A. Estimation of Human Exposure 60 1. Ingestion of Fish 60 2. Exposure to Floodplain Soil 61 B. Monte Carlo Analysis 62 C. Fish Sample Preparation 62 D. Evidence of Human Toxicity from PCB Exposure 63 Vffl. CONCLUSIONS 65 IX. REFERENCES 66 APPENDICES -n Appendix A: Hmong Survey Appendix B: Fall Creel Survey Appendix C: Spring Creel Survey Appendix D: Monte Carlo Simulation Appendix E: Sheboygan River Smallmouth Bass Population Estimates TABLES Table 1-1: Lifetime Tumorigenic Risks for Hypothetical Receptors from Ingestion of Fish from the Sheboygan River (50th and 90th Percentile) 6 Table 1-2: Lifetime Tumorigenic Risks for Hypothetical Adult and Child Receptors Exposed to Floodplain Soils (50th and 90th Percentile) 7 Table n-1: Comparison of Nomenclature Used to Describe Locations Along the Sheboygan River 11 Table ffl-1: Summary of PCB Concentrations Detected in Fish from the Sheboygan River 16 Table ffl-2: Summary of PCB Concentrations Detected in Floodplain Soils 18 Table IV-1: Relative Cancer Slope Factors (CSFs) for PCBs Based on Chase et al. (1989 and Updates of Chase et al.) 27 Table V-l: Cumulative Distributions of LADDs Due to Exposure to Soils for Hypothetical Child Receptors (mg/kg-day) 38 ENVIRON CONTENTS (continued) Page TABLES (Cont'd) Table V-2: Cumulative Distributions of LADDs Due to Exposure to Soils for Hypothetical Child Receptors (mg/kg-day) 39 Table V-3: Cumulative Distributions of LADDs Due to Ingestion of Fish from Area 3 (mg/kg-day) 40 Table V-4: Cumulative Distributions of LADDs Due to Ingestion of Fish from Area 3 (mg/kg-day) 41 Table V-5: Intake Assumptions for Fish Consumption 42 Table V-6: Intake Assumptions for Incidental Soil Ingestion 44 Table V-7: Intake Assumptions for Dermal Contact with Soil 45 Table V-8: Cumulative Distributions of PCB Concentrations in Fish (mg/kg) 47 Table V-9: Cumulative Distributions of Exposure Parameters for Fish Ingestion 50 Table V-10: Cumulative Distributions of PCB Concentrations in Soil (mg/kg) 52 Table V-ll: Cumulative Distributions of Exposure Parameters for Soil Ingestion and Dermal Contact for Hypothetical Adult Receptors 53 Table V-12: Cumulative Distributions of Exposure Parameters for Soil i Ingestion and Dermal Contact for Hypothetical Child Receptors 54 Table VI-1: Cumulative Distributions of Total Cancer Risk Ingestion of Fish from the Sheboygan River 57 Table VI-2: Cumulative Distributions of Total Cancer Risk Soil Ingestion and Dermal Contact 59 FIGURES Figure ffl-l: Sheboygan River Fish Consumption Study Survey Sites 14 Figure III-2: Sheboygan River Floodplain Soil Sampling Sites 17 ENVIRON I. EXECUTIVE SUMMARY This risk assessment, prepared on behalf of Tecumseh Products Company (Tecumseh), evaluates the potential human health risks associated with exposure to polychlorinated biphenyls (PCBs) at current conditions in the Sheboygan River and the floodplain soils adjacent to the Sheboygan River. This report evaluates the potential for long-term health-related effects, specifically the carcinogenic risk, posed to hypothetical receptors exposed to PCBs through ingestion of fish caught in the Sheboygan River as n well as through incidental ingestion of, and dermal contact with, floodplain soils. The — ' results presented in this report indicate that, based on site-specific information for fish ™n consumption and on current PCB levels in fish, that the risks associated with either fish _ consumption or direct contact with flood plain soils are acceptable according to USEPA guidelines. The U.S. Food and Drug Administration has established a tolerance level of 2.0 \J mg/kg (2.0 ppm) total PCBs hi fish fillets for interstate commerce (USFDA 1988). According to the Agency for Toxic Substances and Disease Registry's Toxicological Profile ' for Selected PCBs (199 la), the mean concentration of PCBs in whole freshwater fish throughout the United States is 0.5 mg/kg (0.5 ppm). A study published by Humphrey (1988) reported that the median (50th percentile) concentrations of PCBs in cooked Lake Michigan fish (trout, salmon, pike, perch, walleye and whitefish) ranged from 0.17 ppm (pike, perch, walleye and whitefish) to 3.0 ppm (lake trout). The 50th percentile values used to evaluate potential risk associated with ingestion of fish (i.e., uncooked fillets from the Sheboygan River) were generally below 3.0 ppm, indicating in a qualitative sense that fish in the Sheboygan River have not bioaccumulated PCBs to any greater extent than fish in other parts of the United States. The levels of PCB in fish that are consumed are reduced by customary removal of _ fat and dark tissue and by cooking. The recently-released Health Guide for People Who -I- ENVIRON Eat Sport Caught Fish from Wisconsin Waters (WDOH 1993) emphasizes the point that "PCBs and many pesticides usually build up in a fish's fat deposits and just beneath the skin rather than in muscle tissue. By removing the fat before you cook and eat these fish..., you can reduce PCB and pesticide levels..." The guide further advises removal of all skin, the dark flesh on the top of the fish along the backbone, the fat belly meat along the bottom of the fish and the V-shaped wedge of fat along the lateral line of the fish. Cooking preparation, especially baking or broiling trimmed fish on a rack or grill further decreases the concentration of PCBs in the fish (WDOH 1993). These recommendations are further supported by the Great Lakes Sport Fish Advisory Task Force's (GLSFATF) Protocol for a Uniform Great Lakes Sport Fish Consumption Advisory (GLSFATF 1993). The PCB concentrations for Sheboygan River fish presented in this report were obtained from the analysis of uncooked fillets from which the dark flesh had not been removed. Had the fillets been trimmed as recommended by the Wisconsin I Health Guide and cooked, the analytical data would have yielded substantially lower PCB levels in the fish species, and, as a result, the potential risk associated with ingestion of the fish would be lower than calculated. This analysis considers the most recent sampling data available for each species of fish. Data from 1992 were used for salmon and steelhead trout, while 1993 data were w I used for bass and carp. These analytical data best represent current exposure concentrations for fish ingestion, without taking into account reductions associated with preparation. Although PCB concentrations in fish decreased markedly following land- >- based removal activities in 1979, they increased somewhat following dredging in 1989 and 1990. Since that time, the PCB concentrations have tended to decrease and, absent intervening activities, are likely to continue to decrease, although existing fish may live for some time and contain PCB concentrations near current levels. The current exposure concentrations in fish were used to estimate future concentrations for this risk assessment. This assumption will also overestimate the carcinogenic risk posed to hypothetical receptors in the fish ingestion scenario, as PCB levels in the Sheboygan River are expected to decrease, not remain constant, in the future. The organization of this report is based on the individual steps of the risk assessment process as described by the National Research Council of the National Academy of -2- ENVIRON Sciences in a report by its Committee on the Institutional Means for Assessment of Risk in Public Health (NRC 1983). The chemicals detected in environmental media are identified and the analytical data are summarized in the Hazard Identification section (Section III). The lexicological properties of the detected chemicals are discussed and health-effects criteria used in the quantitative risk assessment are summarized in the Toxicity Assessment section (Section IV). The Exposure Assessment section identifies populations that may be exposed to the chemicals, and exposure pathways are selected for further evaluation (Section V). The magnitude, frequency and duration of exposure are estimated and the potential chemical intakes are quantified in Section V as well. The Risk Characterization section integrates human exposure information and toxicity criteria to develop estimates regarding the nature and magnitude of potential risk to human health (Section VI). This risk assessment was conducted using Monte Carlo simulation techniques to quantify risks and provide an analysis of uncertainty in exposure assumptions (USEPA 1992a). Monte Carlo analysis uses probability density functions or cumulative frequency distributions instead of single point estimates as input variables for the risk calculations.