Lowest amount of a substance that, when introduced into the body, may cause death to individual species of test animals under a defined set of conditions.
PAC, 1993, 65, 2003
(Glossary for chemists of terms used in toxicology (IUPAC Recommendations 1993))
on page 2071
IUPAC. Compendium of Chemical Terminology, 2nd ed. (the "Gold Book"). Compiled by A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford (1997). XML on-line corrected version: http://goldbook.iupac.org (2006-) created by M. Nic, J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN 0-9678550-9-8. doi:10.1351/goldbook