06909 IUPAC Gold Book - lowest observed adverse effect level 10.1351/goldbook.LT06909 LT06909 current initialism: LOAEL 1 Lowest concentration or amount of a substance, found by experiment or observation, which causes an adverse alteration of morphology, functional capacity, growth, development, or life span of a target organism distinguishable from normal (control) organisms of the same species and strain under defined conditions of exposure. exposure https://goldbook.iupac.org//terms/view/ET06811 morphology https://goldbook.iupac.org//terms/view/MT07285 strain https://goldbook.iupac.org//terms/view/S06037 PAC, 1993, 65, 2003. 'Glossary for chemists of terms used in toxicology (IUPAC Recommendations 1993)' on page 2065 (https://doi.org/10.1351/pac199365092003) PAC, 2001, 73, 993. 'Risk assessment for occupational exposure to chemicals. A review of current methodology (IUPAC Technical Report)' on page 1023 (https://doi.org/10.1351/pac200173060993) https://goldbook.iupac.org/terms/view/LT06909/html https://goldbook.iupac.org/terms/view/LT06909/json https://goldbook.iupac.org/terms/view/LT06909/plain Citation: 'lowest observed adverse effect level' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. 10.1351/goldbook.LT06909 The IUPAC Gold Book is licensed under Creative Commons Attribution-ShareAlike CC BY-SA 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) for individual terms. If you are interested in licensing the Gold Book for commercial use, please contact the IUPAC Executive Director at executivedirector@iupac.org . The International Union of Pure and Applied Chemistry (IUPAC) is continuously reviewing and, where needed, updating terms in the Compendium of Chemical Terminology (the IUPAC Gold Book). Users of these terms are encouraged to include the version of a term with its use and to check regularly for updates to term definitions that you are using. 2026-04-23T16:19:11+00:00