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SECTIONFOUR Aposure Assesslment <br /> o Averaging tune for noncwcinogemc effects is based on exposure duration, since these <br /> effects are evaluated based on whether the daily intake of a chemical exceeds its <br /> threshold dose Averaging tunes were 25 years for occupational exposures and 30 <br /> years for the residential exposures(EPA., 1989 and DTSC, 1993) <br /> o The averaging time for carcinogenic effects was 70 years (EPA,, 1989 and DTSC, <br /> 1993) <br /> r4.5.2 Assumptions for Inhalation of Volatiles, Groundwater Ingestion, Dermal Exposure, <br /> and Soil Ingestion <br /> Intake factors for exposure via inhalation of volatiles from soil emissions, groundwater ingestion, <br /> dermal exposure, and soil ingestion were estimated for occupational and potential off-site residential <br /> 1 receptors The following assumptions were used to estimate exposure to chemicals of concern through <br /> this route <br /> o The inhalation rate for occupational and residential receptors were 20 m�/day (EPA., 1989 <br /> and DTSC, 1993) <br /> o Residents were assumed to drink an average of 2 liters of groundwater per day from the <br /> hypothetical wells(EPA, 1989 and DTSC, 1993) <br /> 0 The RNIE adult soil ingestion rate for occupational employees was 100 mg/day (EPA, <br /> 1989 and DTSC, 1993) <br /> o Skin surface area of 5,800 cm2 was used for the occupational RNTE day (EPA, 1989 <br /> and DTSC, 1993) <br /> All exposure factors are included in Output Table 1 in Appendix A <br /> 0 TkigOM73008NA%STOCKTONIREPORT%SHOREP01 D0C1-FEB4MB73009NMSNA 4-15 <br />