Assessing Exposure
EPA develops methods and models that use sampling data to inform risk decisions. For example, research focuses on understanding the likelihood of human exposure to contaminants by modeling and evaluating exposure pathways. By increasing understanding all of the potential human exposure pathways, decision makers are able make more informed remediation decisions during a contamination incident.
Exposure is contact between a contaminant and a human or ecological (e.g. fish, wildlife) receptor. EPA considers risk to be the chance of harmful effects to human health or to ecological systems resulting from exposure to an environmental contaminant. Understanding the risks to human health from the release of contaminants is important to setting priorities, predicting and preventing contamination incidents and responding quickly and effectively to save lives during and after an incident.
Risk is relative to the amount of exposure. Of special concern to the Agency is the risk posed by exposure to contaminants termed “agents,” those contaminants that could be adapted to be used as weapons. EPA assesses information on exposure and toxicity for the chemical (including biotoxins), biological (including microbial pathogens), and radiological (CBR) agents that might contaminate structures, outdoor areas, or water systems. 
Industrial Air Pollution
EPA uses risk assessment to characterize the nature and magnitude of risk posed by CBR agents. Exposure pathways encompass the ways in which the receptors contact contaminants. Exposure assessment describes the movement of a contaminant from its source through the environment to receptors. A complete exposure pathway includes the source of the contamination, its transport through the environment (e.g., air, water, or soil), and the route by which it enters the body (generally inhalation, ingestion, or direct contact). Researchers provide the scientific basis to assess exposure pathways and utilize exposure modeling for CBR contaminants to support risk assessment.