Hm. Thompson et al., PREDICTION OF INTERSPECIES DIFFERENCES IN THE TOXICITY OF ORGANOPHOSPHORUS PESTICIDES TO WILDLIFE - A BIOCHEMICAL APPROACH, Comparative biochemistry and physiology. Part C, Pharmacology toxicology & endocrinology, 111(1), 1995, pp. 1-12
The activation of organophosphorus pesticides and sensitivity of 'B' e
sterases to inhibition (I-50) by the oxon metabolites were investigate
d in brain, liver and serum as the basis for a model to predict the to
xicity of organophosphorus pesticides to four avian species. There wer
e statistically significant correlations between LD(50) and brain rate
of activation of the OP (r = 0.68), brain acetylcholinesterase I-50 (
r = 0.88), and serum carboxylesterase I-50 (r = 0.60). A significant p
roportion of the oxon produced within the liver is unlikely to reach t
he brain, due to irreversible binding by 'B' esterases. The production
of the active oxon form of the pesticide within the brain, and the se
nsitivity of the brain AChE to inhibition, are probably the most impor
tant factors in determining the avian toxicity of organophosphorus pes
ticides.