EPA-Expo-Box (A Toolbox for Exposure Assessors)
An exposure route is the way that a contaminant enters an individual or population after contact (IPCS, 2004). Typically, exposure occurs by one of three exposure routes—inhalation, ingestion, or dermal. Dermal exposure can result from skin contact with contaminated environmental media, including water (e.g., during bathing, washing, swimming); sediment (e.g., while wading, fishing); outdoor soil or dust (e.g., during recreational, gardening, or construction-related activities); and indoor dust that has settled on carpets, floors, clothing, counter tops, or other surfaces. Water can become contaminated via direct discharges to surface water (i.e., point sources), indirect releases, and migration to groundwater or other water sources to which people may be exposed dermally. Soil, house dust, or other materials might become contaminated as a result of intentional application (e.g., pesticide use), deposition of particulate matter (e.g., from atmospheric pollutants), or transport from other media (e.g., water). Human receptors could also come into contact with chemicals from consumer products directly (e.g. during use) or indirectly (e.g., chemicals that have settled on indoor or outdoor surfaces).
Estimating exposure from dermal contact requires information on the concentration of the contaminant in the medium that is contacted; timeframe of exposure (contact frequency and duration); and other factors that affect dermal exposure—for example, skin surface area, dermal adherence of solids to skin (e.g., soil or sediment loading), film thickness of liquids on skin (e.g., after use of consumer products such as cleaning solution or soap), and/or residue transfer factors (e.g., to characterize the transfer of contaminant residues from a contaminated indoor or outdoor surface to the skin of a receptor).
Calculations to estimate dose from dermal contact are provided in this module as are various tools available for evaluating potential exposure concentrations. Exposure scenarios, exposure factors, and guidance for assessing exposure via dermal contact are also provided.