asymptotic threshold concentration

initialism: ATCN
https://doi.org/10.1351/goldbook.14453
Concentration of a chemical at which some percentage of a population of test organisms is in a state of approximate homeostasis for a prolonged period of time (\(\pu{48 h}\) or more).
Notes:
  1. This can be demonstrated as the concentration at which the toxicity curve is approximately asymptotic (parallel) to the time axis.
  2. The asymptotic \(\pu{LC_{50}}\) is the concentration at which the \(\pu{LC_{50}}\) remains constant no matter how long exposure continues, i.e., there is no evidence of significantly increasing effects due to a longer exposure time.
Source:
PAC, 2009, 81, 829. (Glossary of terms used in ecotoxicology (IUPAC Recommendations 2009)) on page 841 [Terms] [Paper]
Citation: 'asymptotic threshold concentration' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.14453 RIS BibTex EndNote
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