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. Ingestion exposure can occur via consumption of contaminated food—fruits and vegetables, meats, fish and shellfish, dairy products, fats, grain products, and human milk—or supplements and ingestion of water and other liquids. Food can contain chemical residues as a result of intentional application (e.g., pesticide use), deposition of particulate matter onto edible produce (e.g., from atmospheric pollutants), and/or biotic uptake and accumulation from contaminated soil or water (e.g., irrigation water, update of contaminants by fish or livestock). Ingestion exposure can also occur via the intentional or inadvertent non-dietary ingestion of soil, dust, or chemical residues on surfaces or objects that are contacted via hand-to-mouth or object-to-mouth activity (especially for young children). (See the module on Lifestages in the Lifestages and Populations Tool Set of EPA-Expo-Box for resources specific to this population.) Soil can become contaminated as a result of direct discharges to soil, atmospheric deposition, or transport from other media (e.g., water). Contaminated soil can also be tracked indoors and contribute to contaminated house dust.
Estimating exposure from ingestion requires information on the concentration of the contaminant in the medium that is ingested, ingestion rate, and the timeframe of exposure. Estimating exposure from non-dietary ingestion may also require information on the frequency of hand-to-mouth or object-to-mouth contact.
Calculations to estimate dose from dietary and non-dietary ingestion 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 ingestion are also provided.