List of ATSDR MRLs
补偿（电）箱上MRLs and Health Effects
通用公共信息
The Comprehensive Environmental Response，Compensation，and Liability Act（CERCLA）[42U.S.C.9604et seq.]，as amended by the Superfund Amendments and Reauthorization Act（SARA）[Pub.L.99499]，requires that the Agency for Toxic Substances and Disease Registry（ATSDR）develop jointly the Agency Agency for Proency。（EPA），in order of priority，a list of hazardous substances most commonly found at facilities on the CERCLA National Priorities List（NPL）（42U.S.C.9604（i）（2））；prepare toxicological profiles for each substance included on the priority list of hazardous substances，and to ascertain significant human exposure levels（SHELs）for hazardous substances in the environment，and the associated acute，subacute，and chronic health effects（42U.S.C.9604（i3））；and assure the initiation of a research program to fill identified data needs associated with the substances（42U.S.C.9604（i）（5））。
The ATSDR Minimal Risk Levels（MRLs）were developed asan initial response to the mandate。Following discussions with scientists within the Department of Health and Human Services（HHS）and the EPA，ATSDR chose to adopt a practice similar to that of the EPA’s Reference Dose（RfD）and Reference Concentration（RfC）for deriving substance specific health guidance levels for non-neoplastic endpoints。An MRL is an estimate of the daily human exposure to a hazardous substance that is likely to be without appreciable risk of adverse non-cancer health effects over a specified duration of exposure.These substance specific estimates，which are intended to serve as screening levels， are used by ATSDR health assessors and other responders to identify contaminants and potential health effects that may be of concern at hazardous waste sites。It is important to note that MRLs are not intended to define clean up or action levels for ATSDR or other Agencies。
The toxicological profiles include an examination，summary，and interpretation of available toxicological information and epidemiologic evaluations of ahazardous substance.During the development of toxicological profiles，MRls are derived when ATSDR determines that reliable and sufficient data exist to identify the target organ（s）of effect or the most sensitive health effect（s）for a specific duration for a given route of exposure to the substance。MRls are based on non-cancer health effects only and are not based on a consideration of cancer effects.Inhalation MRls are exposure concentrations expressed in units of parts per million（ppm）for gases and volatiles，or milligrams per cubic meter（mg/m3）for particles。Oral MRLs are expressed as daily human doses in units of milligrams per kilogram per day（mg/kg/day）。Radiation MRLs are expressed as external exposures in units of millisieverts。
ATSDR uses the no observed adverse effect level/uncertainty factor（NOAEL/UF）approach to derive MRLs for hazardous substances。They are set below levels that，based on current information，might cause adverse health effects in the people most sensitive to such substance-induced effects.MRLs are derived for acute（1-14days），intermediate（>14-364days），and chronic（365days and longer）exposure durations，and for the oral and inhalation routes of exposure.Currently MRLs for the deral route of exposure are not derived because ATSDR has not yet identified a method suitable for this route of exposure.MRLs are generally based on the most sensitive substance induced end point considered to be of relevance to hus.ATious serteffects（such as irreparable damage to the liver or kidneys，or birth defects）as a basis for establishing MRLs.Exposure to a level above the MRL does not mean that adverse health effects will occur。
MRls are intended to serve as as screening tool to help public health professionals decide where to look more closely.They may also be viewed as a mechanism to identify those hazardous waste sites that are not expected to cause adverse health effects.Most MRls contain some degree of certy of untick cological information on the people who might be most sensitive（e.g.，infants，elderly，and nutritionally or immunologically compromised）to effects of hazardous substances.ATSDR uses a conservative（i.e。，protective）approach to address these uncertainties consistent with the public health principle of prevention.Although human data are preferred，MRls often must be based on animal studies because relevant human studies are lacking.In the absence of evidence to the contrary，ATSDR assumes that humans are more sensitive than animals to the effects of hazardous substances that certain persons may be particularly sensitive.Thus the resulting MRL may be as much as a hundredfold below levels shown to be nontoxic in laboratory animals.When adequate information available，physiologically based pharmacokinetic（PBPK）modeling and benchmark dose（BMD）modeling have also been used asan adjunct to the NOAEL/UF approach in deriving MRLs。
Proposed MRLs undergo arigorous review process.They are reviewed by the Health Effects/MRL Workgroup within the Division of Toxicology and Human Health Sciences；an expert panel of external peer reviewers；the agency wide MRL Workgroup，with participation fromother federal agencies， including EPA；and are submitted for public comment through the toxicological profile public comment period.Each MRL is subject to change as new information becomes available concomitant with updating the toxicological profile of the substance.MRls in the most recent toxicological profiles supperde reviousleofforthis linkto see our current MRLs。