Groundwater contamination by PCE and TCE: ATSDR's approach to evaluating public health hazard

The Agency for Toxic Substances and Disease Registry (ATSDR) conducts public health assessments and consultations that evaluate the potential health impacts from human exposure to hazardous substances and recommend appropriate actions needed to mitigate or prevent exposures. ATSDR has conducted health evaluations for more than 80 federal facilities. Eighteen sites involve human exposure to tetrachloroethylene (PCE) or trichloroethylene (TCE) in groundwater. ATSDR uses a two-tiered approach to evaluate health hazard or risk from exposure. The first tier of analysis is described as a rote algorithmic determination of risk (RAD) and is used to screen exposure conditions that do not pose a health hazard under conservative assumptions of exposure. The second tier is a weight-of-evidence analysis that incorporates the traditional elements of risk assessment within the broader context of professional and biomedical health hazard for exposure pathways involving groundwater contamination at federal facilities.