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' DRAFT <br /> were used to evaluate the lead concentrations for each applicable investigation area. The <br /> input parameters used in the blood lead level evaluation included the drinking water <br /> concentration of lead for the City of Stockton (1999) and the annual average ambient air <br /> lead concentration (U.S. EPA, Airs Data, 1999) of 0.01 µg/m3. According to the City of <br /> Stockton 1998 Annual Water Quality Report, lead was not present in groundwater at a <br /> detection level of 5 gg/L,however, this value was used in the model as a conservative <br /> estimate of lead in drinking water. In addition to the use of city-specific drinking water <br /> data and ambient air data, the Leadspread model was modified to incorporate an updated <br /> intake lead concentration from dietary contribution. A value of 2.56 gg/kg dietary lead <br /> contribution was used instead of the default parameter of 10 gg/kg based on an updated <br /> U. S. Food and Drug Administration"market basket"survey for the period between 1986 <br /> ' through 1991 (CalEPA,personal communication, 1999). Results of the lead risk <br /> assessment are presented in Table 19 and are used to evaluate soil lead concentrations <br /> present at Areas 2A, 213, 3, and 4, and as discussed in the following sections. <br /> 2.1 Area 2A <br /> The noncarcinogenic hazard indices presented in Table A-6 indicate that HIs were greater <br /> ithan 1 for construction worker, landscape maintenance worker, commercial/industrial <br /> worker, and residential receptor. Elevated HIs for these receptors are primarily attributed <br /> to the presence of 2-methyl naphthalene in soil. It should be noted that toxicity data for <br /> naphthalene are used as a surrogate for 2-methyl naphthalene and may result in a <br /> conservative estimate of noncarcinogenic hazard. <br /> tThe excess cancer risks for the construction worker, landscape maintenance worker, and <br /> commercial worker were 1.03E-06, 8.36E-05, and 4.38E-05, respectively, and within the <br /> acceptable range of risks between 1E-04 to 1E-06 for non-residential site uses. However, <br /> the excess cancer risk for the resident was estimated at 1.03E-04, which is two orders of <br /> magnitude higher than the acceptable risk of 1 E-06 for residential site use. Excess cancer <br /> risk at Area 2A primarily driven by the presence of arsenic in the soil. Arsenic ranged <br /> ' SOMA 99-2218 15 12/10/99 <br />