Illustrating Chemical Transport Mechanisms and Exposure Pathways

There are three basic steps to an exposure assessment  

Not everyone will be exposed to chemicals associated with a site. In this step, the types of people that could be exposed are identified. Using the gas station example, the gas station attendants will represent the people most likely to be exposed to chemicals at the site. People refueling their cars will also be exposed. Small children are unlikely to be exposed to any appreciable degree. Also, if the leak were to be fixed, workers could directly contact the contaminated soil during excavation and removal of the soil. Similarly, if chemicals were present in groundwater at a site used for an office building, we could expect that office workers in the building would be the primary exposed receptors. 

Once potential receptors cu e identified, the ways in which they may contact chemicals need to be defined. This is done by identifying complete exposure pathways. There are four components that must all be present for an exposure pathway to be complete  

A source and mechanism of chemical release to the environment (e.g., leaking underground storage tank) 

An environmental transport medium for the chemical (e.g., movement of the chemical into air) 

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Figure 8.2. Diagram Illustrating Chemical Transport Mechanisms and Exposure Pathways...

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