maximum tolerable concentration (MTC)

https://doi.org/10.1351/goldbook.M03768
Highest concentration of a substance in an environmental medium that does not cause death of test organisms or species (denoted by LC0).
Source:
PAC, 1993, 65, 2003. 'Glossary for chemists of terms used in toxicology (IUPAC Recommendations 1993)' on page 2067 (https://doi.org/10.1351/pac199365092003)