Chou, CHSJ; Holler, J; de Rosa, CT
The Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) (42 U.S.C 9604 et seq.), as amended by the Superfund Amendments and Reauthorization Act (SARA) (Pub. L. 99-499), requires that the Agency for Toxic Substances and Disease Registry (ATSDR) develop jointly with the U.S. Environmental Protection Agency (USEPA), in order of priority, a list of hazardous substances most commonly found at facilities on the CERCLA National Priorities List (NPL) (42 U.S.C 9604(i)(2)); prepare toxicological profiles for each substance included on the priority list of hazardous substances, and ascertain in the toxicological profiles, significant human exposure levels (SHELs) for hazardous substances in the environment, and the associated acute, subacute, and chronic health effects (42 U.S.C 9604(i)(3)); and assure the initiation of a research program to fill identified data needs associated with the substances (42 U.S.C. 9604(i)(5)). The ATSDR Minimal Risk Levels were developed as an initial response to the mandate and to provide screening levels for health assessors and other responders to identify contaminants and potential health effects that may be of concern at hazardous waste sites and releases. An MRL is an estimate of the daily human exposure to a hazardous substance that is likely to be without appreciable risk of adverse noncancer health effects over a specified duration of exposure. In this paper, we describe ATSDR's current approach for deriving MRLs for priority hazardous substances. The MRLs for a particular substance are published in the toxicological profile for that substance. A listing of the current published MRLs as of December 1997 is also provided.