Narcosis is a reversible state of arrested activity of
protoplasmic structures caused by a wide variety of
organic chemicals. Veith et al. (1) demonstrated that
this nonspecific mode of action was responsible for lethality
in the fathead minnow (Pimephales promelas)
for many alcohols, ketones, ethers, alkyl halides, and
benzene derivatives. The structure-toxicity relationships
developed by both Konemann (2) and Veith et al.
(1) are very similar and accurately estimate the LC50
of nonreactive, nonpolar chemicals for a wide variety of
aquatic organisms (3) using only the n-octanol/water
partition coefficient (log P). The equations presented
(1,2) have become known as baseline toxicity models
that predict the toxicity of chemicals that act through
the nonspecific mechanism of narcosis. In general, more
specific mechanisms produce greater toxicity than baseline
narcosis.