Laserfiche WebLink
Phase 11 Environmental Site Assessment <br /> Mountain House Neighborhood G <br /> July 9,2002 <br /> Page 8 <br /> The media values chosen for the calculations are the highest concentrations detected in the soil samples as <br /> presented in Table 1. <br /> 7.2.3 Risk Assessment Methods <br /> Toxicity Assessment <br /> A toxicity and environmental fate profile was developed for all contaminants using the Cal/EPA Cancer <br /> Potency Factors and the USEPA Integrated Risk Information System (IRIS), except for those without <br /> published toxicity reference values. See toxicity data for detected constituents in Appendix B. Published <br /> toxicity reference values for endosulfan were used for endosulfan I and R. <br /> Risk and Hazard Characterization <br /> As summarized in Table 3 on page 11, gamma-BHC, DDD, DDE, DDT, heptachlor, kepone, and <br /> tetrachlorvinphos are associated with cancer risks. Cancer risk and non-cancer hazard quotients were <br /> calculated for all of the COPC, as applicable using Cal/EPA PEA methods and default values based on <br /> toxicity data. The evaluation of risk was performed by Excel spreadsheets using the EPA Reference Doses <br /> (EPA IRIS, 2000) and the Cal/EPA PEA methods(PEA June 99—B 11, B 13).The evaluation of hazard was <br /> performed by Excel spreadsheets using the EPA Reference Doses(EPA IRIS, 2000) and the Cal/EPA PEA <br /> methods(PEA June 99—B 12, B 14). <br /> The reduced formula for the risk due to soil by oral and dermal routes(pg. B-11) is: <br /> Risk,oit =(SFo x Cs x 6.1 x 10"')+(SFo x Cs x 3.4 x 10-6)+(SFo x Cs x 9.7 x 10'6 x ABS) + (SFo x Cs x <br /> 3.4 x 10-'x ABS) <br /> Where: <br /> Cs=concentration in soil,(mg/kg) <br /> SFo=oral cancer slope factor,(mg/kg-day)-1 <br /> ABS =absorption fraction of chemical from soil <br /> and numeric coefficients were generated based on the following default exposure factors: <br /> IRs= ingestion rate for soil= 100 mg/day(adult), 200 mg/day(child) <br /> BW=body weight=70 kg(adult), 15 kg(child) <br /> AT=averaging time(exposure)=70 yrs. <br /> EF = exposure frequency = 365 day/yr (soil ingestion & child dermal contact), 100 day/yr (adult dermal <br /> contact) <br /> ED=exposure duration=30 yrs. (adult), 18 yrs. (child) <br /> SA=skin surface area=5,800 CM2/day(adult),2000 cm2/day(child) <br /> AF=adherence factor= 1 mg/cm2 <br /> NtooI <br /> iCONDOR <br />