Greatest concentration or amount of a substance, found by experiment or observation,
that causes no alterations of
morphology, functional capacity, growth, development, or life span of target organisms distinguishable
from those observed in normal (control) organisms of the same species and
strain under the same defined conditions of exposure.
Source:
PAC, 1993, 65, 2003
(Glossary for chemists of terms used in toxicology (IUPAC Recommendations 1993))
on page 2076