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i <br /> lifetime. For soil ingestion, the assumed intake rate of 0.2 g/day Z-s <br /> based on a 5-year exposure period for a 16 Kg child and is assumed to <br /> represent an average scenario in which children ages 1-6 years of age <br /> ingest an average amount of soil on a daily basis. <br /> To evaluate the potential human exposure to airborne dust, the state <br /> annual average for suspended particulate matter (30 ug/m3) was assumed. <br /> RISK CHARACTERIZATION <br /> The final step in developing a site specific MHA is the risk character- <br /> ization. In this step, the potential for exposure to chemicals is <br /> related to their toxicity. The resulting relationship forms the basis <br /> of the baseline risk to humans. For carcinogens, this baseline risk <br /> describes the incremental probability of individuals exposed to site as <br /> an excess above a one-in-a-million (10"6) risk. For non-cancer toxicity <br /> (systemic toxicant) , the baseline risk defines the probability of <br /> sensitive individuals suffering adverse effects resulting from exposure <br /> to site conditions. This probability is described by the ratio of the <br /> individual 's exposure level to the Reference Dose for each chemical <br /> exposure. <br /> The overall potential for adverse effects resulting from exposure to <br /> multiple chemicals in soil is assessed using a hazard index (HI) . Using <br /> this approach, the additivity of carcinogenic effects and systematic <br /> toxicity effects can be evaluated. Carcinogens and systematic toxicants <br /> which cause similar systematic effects are evaluated separately. A <br /> hazard index of greater than or equal to one indicates a possible need <br /> for corrective measures at a site. <br /> For systemic toxicants with similar effects, the hazard index (HIT) for <br /> a site is calculated by; <br /> HIT = the sum from i=1 to n of E,/AE, <br /> where <br /> n = total number of toxicants <br /> E = average concentration detected of the ith toxicant <br /> AL, = maximum acceptable level for the lth toxicant <br /> For carcinogens, the hazard index (HIS) for a site is calculated by- <br /> HIC = the sum from 3=1 to n of E,/DR, <br /> where <br /> n = total number of carcinogens <br /> E = average concentration detected of the j carcinogen <br /> Dh� = dose at set level of risk for the 3th carcinogen <br /> Pre-excavation Soil <br /> Ingestionof Soil . A comparison of the range of concentrations of <br /> pesticides and their average concentrations with the potentially <br /> i <br /> WPI13 B-3 882526.01 <br />