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e <br /> * r.r <br /> t-y <br /> • Exposure duration refers to the number of years spent on or near the site. <br /> Occupational average and RME exposure durations were 5 years and 25 <br /> years, respectively (USEPA 1991). <br /> r, • Residential receptor exposure durations were assumed to be 9 years for <br /> the average case and 30 years for the RME (USEPA 1989). For child <br /> residents a 6-year exposure duration was evaluated. <br /> • Body weights derived from USEPA (1989 and 1991) were the same for <br /> RME and average exposures. The body weight was 70 Kg for adult <br /> residents and occupational employees, and 15 Kg for children. <br /> • Averaging time for noncarcinogenic effects is based on exposure duration, <br /> since these effects are evaluated based on whether the daily intake of a <br /> chemical exceeds its threshold dose. Averaging times were 5 years and 25 <br /> years for average and RME occupational exposures, respectively. The <br /> corresponding averaging times for adult residential exposure were 9 years <br /> for the average case and 30 years for the RME and 6 years for the child <br /> y <br /> RME and average resident. <br /> • The averaging time for carcinogenic effects was 70 years. <br /> 4.5.2 Assumptions for Inhalation of Volatiles <br /> 'r <br /> Intake factors for exposure via inhalation of volatiles from soil emissions were estimated <br /> for occupational and future residential receptors. The following assumptions were used <br /> to estimate exposure to chemicals of concern through this route. <br /> Inhalation rates vary in proportion to the rate of exertion. The average <br /> inhalation rate for occupational receptors was 1.8 m3/hr and for the RME, <br /> the rate was 2.5 m3/hr. The average rate assumes activities such as the <br /> use of a sledge hammer. The RME rate corresponds to efforts like trench <br /> digging (EPA 1991). <br /> • The inhalation rates for residential receptors were based on moderate <br /> activity for the average adult (EPA 1989a). The average inhalation rate <br /> was 0.83 M3/hr and 1.25 M3/hr for the RME scenario. The inhalation rate <br /> _ for both the average and RME child resident scenarios was 0.42 M3/hr <br /> (EPA 1989). <br /> S:\LDC\YELLO.RPT May 4, 1995 4-16 <br /> a.+ <br />