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`. *MW <br /> Concentration of Copper for a Hazard Ouotient of 1 <br /> To determine the concentration of copper to achieve a HQ of one for the adult industrial worker,equation 2 <br /> can be re-arranged to: <br /> Cs= ------ <br /> RJD,x HQ (equation 3) <br /> F4.697 x 10-7 + 2.724 x 10-5 x ABS <br /> r <br /> By substituting the appropriate constants for copper into using equation 3, the concentration of copper <br /> necessary to achieve a HQ equal to one(one-in-a-million risk)for the adult industrial worker is 53,901 mg/kg, <br /> or approximately 54,000 mg/kg. <br /> r <br /> Assumptions <br /> ` Equations 1, 2, and 3 assume factors that lead to an over assumption of the actual hazard from concrete <br /> because these equations assume exposure to soil.The default exposure factor of IR,assumes ingestion of soil, <br /> AF assumes default dermal contact with soil,and ABS assumes dermal absorption of copper from soil.As the <br /> likelihood of concrete ingestion is less than that of soil,and that dermal contact with concrete for the adult <br /> industrial worker is less than the potential of contact with soil,these factors provide an over calculation of the <br /> hazard associate with copper in concrete.As default exposure factors for concrete are not available,it would be <br /> ` safe to assume that the default soil ingestion rate (IR,), the soil to skin adherence factor (AF), and the <br /> absorption fraction of a chemical(ABS)would be lower than those for soil,and would result in a lower HQ <br /> for copper from concrete. <br /> References <br /> Department of Toxic Substances Control (DTSC). 1994.Preliminary Endangerment Assessment Guidance <br /> Manual. State of California Environmental Protection Agency. 1994. <br /> Environmental Protection Agency,Region Di;(EPA Region DQ. 2002.Region MPreliminary Remediation <br /> Goal(PRG) Tables. October. San Francisco. <br /> r <br /> v <br /> r <br /> V <br />