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The RME was obtained by selecting chemical concentrations at the exposure point, the <br /> characteristics of the receptor population, and their activity patterns so that they would <br /> result in a maximum exposure reasonably expected to occur at the site. The intent of <br /> the RME is to conservatively estimate a chemical intake that is well above average but <br /> still within the range of possible exposures. For example, EPA guidance recommends <br /> that the 95 percent upper confidence limit (UCL) on the arithmetic mean concentration <br /> be used for characterizing the chemical concentration for the RME scenario (EPA <br /> 1989b). The UCL is a conservative estimate of concentrations to which a receptor may <br /> be exposed over time. However, for this risk assessment, the highest concentration <br /> detected at the site was used for the RME scenarios in order to be extremely protective <br /> of human health and groundwater. The 95 percent UCL was used for average exposure <br /> scenarios. <br /> 4.4.2 Calculation of Intake Factors <br /> The intake factor is a value that combines the site-specific and receptor specific <br /> assumptions for a given exposure pathway. The intake factor multiplied by the <br /> concentration of a chemical of concern results in an estimate of the chemical intake in <br /> mg/kg/day for that receptor population and exposure pathway. The generic equation <br /> to calculate intake is the following: r <br /> Intake (mg/kg/day) = Concentration x Intake Factor y <br /> Multiplying the intake factor by the concentration of the chemical of concern yields the -- <br /> daily chemical intake. Separate intake factors were calculated for each exposure <br /> pathway and receptor. The values and assumptions used to calculate each intake factor <br /> are dependent on the exposure pathway and receptor pathway being evaluated. A more <br /> detailed description of the values used for intake calculations is presented in Section 4.5 <br /> below. <br /> 4.4.3 Exposure Point Concentrations <br /> Exposure point concentrations are the chemical concentration in environmental media <br /> (soil, groundwater, and air) at the point of contact. Exposure point concentrations were <br /> SALDOYELLO RPT May 4, 1995 4-7 <br />