Exposure assessment
Exposure is defined as the connections between agents and the visible part of human that are dermal, oral, inhalation routes. Exposure assessment is the step that can be measured directly and indirectly, but in generally always measure by concentration in environment indirectly and attention values of fate and transport of chemical agents, and human intake over time.
Dermal exposure is the route that contact by skin. The skin is a barrier between the human inner body and outside environment, so chemical substance can absorb through the dead upper skin parts and then into the tissue and blood vessels in the lower skin layers (Erich, 2004).
For dermal exposure of risk assessment based on dose response relationships, the dermal absorb dose (DAD) equation is used to calculate dose of dermal exposure per day so the descriptions and units of each parameter are shown in Table 2.6. The DAD equation through dermal route is calculated by general equation following (USEPA, 2004)