The ATSDR, in response to congressional mandate under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), develops comparison values to help identify chemicals that may be of concern at hazardous waste sites. One type of these values is called minimal risk levels (MRLs).
An MRL is an estimate of the amount of a chemical a person can eat, drink, or breathe each day without a detectable risk to health. MRLs are developed for health effects other than cancer.
If someone is exposed to an amount above the MRLs, it does not mean that health problems will happen. When health assessors find exposures higher than the MRLs, it means that they may want to look more closely at a site. ATSDR works closely with the Environmental Protection Agency (EPA) at both a national and regional level at sites where exposures are estimated to exceed health-based values such as MRLs.
MRLs can be made for 3 different time periods [the length of time people are exposed to the chemical: acute (about 1 to 14 days), intermediate (from 15-364 days), and chronic (exposure for more than 364 days)].
