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• P7LM1Tminary Environmental Assessment Report Pittman Elementary School,Stockton,CA December 10,2003 Page 23 • heptachlor, heptachlor epoxide, benzene, 1,3-butadiene, chloroform, 1,2-dichloroethane, MTBE, methylene chloride, tetrachloroethene, and trichloroethene are associated with cancer risks. Cancer risk and non-cancer hazard quotients were calculated for all of the COPC in soil, as applicable, using DTSC PEA methods and default values based on toxicity data. The evaluation of risk was performed using Microsoft Excel spreadsheets with the USEPA and OEHHA Slope Factors and the DTSC PEA methods (1999). The evaluation of hazard was performed using Microsoft Excel spreadsheets with the USEPA Reference Doses and the DTSC PEA methods (1999). Oral reference dose values were used for dermal and inhalation exposures for all COPC when reference dose inhalation values were not available. The formulas used to calculate cancer risk and hazard quotients are included in Appendix C. Tables containing screening parameters and the calculated risk and hazard values are also included in Appendix C. Hazard from exposure to lead was evaluated using the DTSC Leadspread 7 Model described in Section 8.2.5. Cancer risk and non-cancer hazard quotients were calculated for all of the soil gas and groundwater COPC, as applicable, using the Johnson and Ettinger Model for Subsurface Vapor Intrusion Into Buildings as discussed by Environmental Quality Management, Inc. (2000). The evaluation of risk and hazard was performed using Microsoft Excel spreadsheets designed for the USEPA and revised by DTSC. The formulas used to calculate cancer risk and hazard quotients are included in Appendix C. Tables containing the calculated risk and hazard values are also included in Appendix C. The detected constituents cyclohexane, heptane, 4-ethyltoluene, and ethanol were not evaluated by the Johnson and Ettinger Model as reference concentrations (RfC) and unit risk factor(URF) values were unavailable. 8.2.4 General Hazard Assessment Results • Maximum increased lifetime cancer risk was calculated for each COPC detected at the site. The cancer risk and hazard quotients associated with each constituent of concern, over soil, air, and soil gas exposure media, and for all constituents of concern, were summed to obtain the total cancer risk and total hazard index posed by these constituents at the highest detected concentrations. The summations are included in Table 17, on the next page. The total calculated cancer risk is 1.84E-05 (18.4 in a million), which is greater than one in a million. Total hazard, calculated to be 0.82, is less than unity. • �', CONDOR