ATSDR’s Process for Defining and Evaluating Exposure Units

This decision tree starts with a text box that states, ”Based on the exposure pathway analysis, do potential or completed pathways exist?” If the answer is no, the tree goes to a text box that states, ”Exposure units do not need to be defined.” If the answer is yes, the tree goes to a text box that states, “Define exposure units per guidance.” This box leads to another text box that asks, “Does the exposure unit have adequate data to evaluate exposure?” If the answer is no, the tree goes to a text box that states, “Identify data gaps and recommend sampling or modeling. Include specifics based on the exposure unit and media in reports.” If the answer is yes, the tree goes to a text box that states, ”Is the maximum concentration of the contaminant in the exposure unit greater than the applicable ATSDR CVs or does the contaminant meet other criteria for inclusion (e.g., a community concern)?” If the answer is no, the tree goes to a decision text box that states, “Exposure in the exposure unit is not a concern.” If the answer is yes, the tree goes to a decision text box that states, “Use the appropriate EPC guidance to calculate EPCs for the exposure pathways of interest for each identified contaminant of concern in the exposure unit. Then calculate doses and continue the health evaluation.”