Abstract:
Dermal contact with contaminated soils is a potential pathway for chemical exposure. A survey of Superfund risk assessments has shown that dermal exposure was predicted to be the dominant route of exposure to contaminants in surface soils at 8% of the sites surveyed, and estimates for lifetime cancer risk from the dermal-soil pathway exceeded 10-4 at 16% of the Superfund sites surveyed (Johnson and Kissel, 1996.) Since cleanup decisions involve tradeoffs between health risks and cleanup costs, good decisions require accurate exposure projections. Lacking empirical data for parameters such as duration and extent of contact with soil, risk assessors have traditionally used default inputs based upon professional judgment. Default parameters typically include a degree of conservatism that is not well characterized. In this study, two populations were surveyed were surveyed via random digit dialing to determine the amount of time spent in activities with potential for contact with soil and the amount of skin exposed during those activities. The survey data are applied to two tasks. In the first, frequency distributions for duration of exposure and exposed skin area are compared between national and regional populations to examine variability in activities relevant to dermal exposure. In the second task, results of the survey are incorporated into a dermal exposure model to generate a dose distribution. The distribution predicted by the model is compared to a dose calculated using default parameters to assess the degree of conservatism providing by the default protocol.