ATSDR’s Decision Tree for Conducting the Exposure Pathway Evaluation

This infographic decision tree starts with a text box that says, “Obtain site information.” Then, there are boxes that ask questions to see if each of the five pathway elements are present. There are three final decision boxes. If the answer to any element question is no, the infographic goes to the “Eliminated Pathway” final decision bubble with the text, “Scientific evaluations are not needed unless community concerns specifically address the pathway.” If the answer to any element question is unknown, the infographic goes to the “Potential Pathway” final decision bubble that states, “Conduct scientific evaluations for all contaminants potentially found in the pathway. Consider options, such as exposure investigations to fill data gaps.” If the answer is yes, the infographic goes to the question for the next element. An arrow leading from the “Obtain site information” bubble goes to, “Pathway Element #1: Is there a source of contamination or release?” If the answer is yes, the infographic moves to “Pathway Element #2: Does contamination migrate through a medium?” If the answer is yes, the infographic moves to, “Pathway Element #3*: Does contamination reach an exposure point?” This box has an asterisk associated with the following note, “There is some flexibility in ATSDR’s analysis. If there is contamination at an exposure point, ATSDR assumes the exposure pathway is complete, even if there isn’t proof that other components of the pathway are present (e.g., environmental fate, a known contaminant source). A health assessor would call this type of scenario a complete exposure pathway – being sure to indicate the assumptions or data gaps about the pathways element(s) in their document.” If the answer is yes, the infographic moves to “Pathway Element #4: Is there a possible route of human exposure?” If the answer is yes, the graphic moves to “Pathway Element #5: Are there potentially exposed populations?” If yes, the arrow moves to “Completed Pathway” that states “Conduct scientific evaluations for all contaminants in the pathway.”