Lowest-observed-adverse-effect level

{{technical|date=February 2018}} The '''lowest-observed-adverse-effect level''' ('''LOAEL'''), or the '''lowest-observed-adverse-effect concentration''' ('''LOAEC'''), is the lowest concentration or amount of a substance found by experiment or observation that causes an adverse alteration of morphology, function, capacity, growth, development, or lifespan of a target organism distinguished from normal organisms of the same species under defined conditions of exposure.<ref>{{cite web |url= http://sis.nlm.nih.gov/enviro/iupacglossary/glossaryl.html |archive-url= https://web.archive.org/web/20071029174250/http://sis.nlm.nih.gov/enviro/iupacglossary/glossaryl.html |url-status= dead |archive-date= October 29, 2007 |title= IUPAC glossary of terms used in toxicology - terms starting with L |work= Environmental Health and Toxicology Specialized Information Services |publisher= U.S. Department of Health & Human Services |access-date= January 9, 2016}} based upon {{Cite journal | last1 = Duffus | first1 = J. H. | last2 = Nordberg | first2 = M. | last3 = Templeton | first3 = D. M. | doi = 10.1351/pac200779071153 | title = Glossary of terms used in toxicology, 2nd edition (IUPAC Recommendations 2007) | journal = Pure and Applied Chemistry | volume = 79 | issue = 7 | pages = 1153 | year = 2007 | doi-access = free }}</ref> Federal agencies use the LOAEL during risk assessment to set approval standards below this level.<ref name="NIOSH Publication No. 2020-106">{{cite book |last1=NIOSH |title=NIOSH Practices in Occupational Risk Assessment |date=March 2020 |publisher=U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health. Publication No. 2020-106 |location=Cincinnati, OH |doi=10.26616/NIOSHPUB2020106 |url=https://www.cdc.gov/niosh/docs/2020-106/ |access-date=18 July 2024}}</ref> thumb|Hypothetical dose-response showing LOAEL

The United States Environmental Protection Agency defines LOAEL as the 'lowest level of a chemical stressor evaluated in a toxicity test that shows harmful effects on a plant or animal. While LOAELs and LOAECs are similar, they are not interchangeable. A LOAEL refers to a dose of chemical that is ingested, while a LOAEC refers to direct exposure to a chemical (e.g., through gills or the skin).<ref>{{cite web|url=http://www.epa.gov/OCEPAterms/lterms.html|archive-url=https://web.archive.org/web/19990417211610/http://www.epa.gov/OCEPAterms/lterms.html|url-status=dead|archive-date=April 17, 1999|title=Terms & Acronyms|first=EPA, OEI, SOR, System Of|last=Registries}}</ref>

== References == {{Reflist}} *{{CRS|article = Report for Congress: Agriculture: A Glossary of Terms, Programs, and Laws, 2005 Edition|url = http://ncseonline.org/nle/crsreports/05jun/97-905.pdf|author= Jasper Womach}}

{{DEFAULTSORT:Lowest-Observed-Adverse-Effect-Level}} Category:Concentration indicators Category:Toxicology