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Mr.Michael Oliphant—CEMC <br /> HHSE Addendum February 22,2012 <br /> Surland Homes-Bridle Creek Page 3 of 6 <br /> ' low end of the range of background concentrations. Arsenic is unlikely to be associated <br /> with crude oil. <br /> ' RESULTS <br /> RESIDENTIAL SCENARIO 1 <br /> ' SAIC selected the maximum detected concentration as the EPC for each COPC as <br /> shown in Table 4; and utilized the same methodology, toxicity criteria(Tables 5 and 6), <br /> and exposure parameters (Table 7) as were utilized in the 2009 HHSE. <br /> ' Cancer Risks <br /> The estimated oral and dermal cancer risks associated with the individual COPCs, and <br /> the summation of cancer risks associated with all COPCs for these exposure routes are <br /> ' provided in Table 8. Estimated indirect inhalation exposures to on-site soils, the risk <br /> associated with individual COPCs, and the summation of inhalation risks are provided <br /> in Table 9. The aggregate risks for oral, dermal, and inhalation cancer risks are provided <br /> ' in Table 10. SAIC estimated the total potential cancer risk to a hypothetical resident <br /> from oral, dermal, and inhalation exposures to on-site soils to be 3E-06. This level of <br /> risk is within, and at the lower end of,the risk management range of 1E-06 to 1E-04 <br /> ' established by the California Environmental Protection Agency(Cal/EPA) and United <br /> States Environmental Protection Agency(EPA). The largest contributors to the excess <br /> cancer risk are benzo(a)anthracene,benzo(a)pyrene, and lead. <br /> ' Non-Cancer Health Hazards <br /> The estimated oral and dermal hazards associated with individual COPCs, and the <br /> ' summation of hazards associated with all COPCs for these routes are provided in <br /> Table 11. The hazards from indirect inhalation exposure associated with individual <br /> COPCs, and the summation of hazards for all COPCs for the inhalation route are <br /> ' provided in Table 12. The aggregate non-cancer hazard for oral, dermal, and inhalation <br /> routes is provided in Table 13. SAIC estimated the total potential non-cancer hazard <br /> from oral, dermal, and inhalation exposures to on-site soils to be 0.4. This level of <br /> ' hazard is below the threshold hazard index of 1, and therefore indicates an acceptable <br /> non-cancer health hazard for exposures to on-site soils for a hypothetical resident. <br /> RESIDENTIAL SCENARIO 2 <br /> SAIC selected the second highest detected concentration as the EPC for each COPC <br /> (Table 4). The maximum detected concentration was selected as the EPC for toluene <br /> ' and ethylbenzene because they were each detected in only one sample. The second <br /> highest detected concentration was the same as the highest detected concentration for <br /> chrysene and pyrene. SAIC utilized the same methodology, toxicity criteria(Tables 5 <br /> ' and 6), and exposure parameters (Table 7) as were utilized in the 2009 HHSE. <br /> Cancer Risks <br /> The estimated oral and dermal cancer risks associated with the individual COPCs, and <br /> ' the summation of cancer risks associated with all COPCs for these exposure routes are <br /> provided in Table 14. The estimated risk from indirect inhalation exposure associated <br />