ABSTRACT
The “biomarker” came into common usage, the inhibition of cholinesterases was recognized as a characteristic indicator of poisoning by organophosphorus and carbamate compounds. In the 1940s Schrader synthesized the first organophosphorus insecticide to have widespread use, parathion; and in the late 1950s the first commercial carbamate insecticide, carbaryl, was synthesized. The relatively low persistence of organophosphorus and carbamate pesticides, compared to organochlorine pesticides, together with their effectiveness has led to wide usage of these compounds. Serum cholinesterases are routinely used to monitor exposure of spray operators to organophosphorus and carbamate compounds, and these methods have been further developed to study the effects of these compounds on wildlife. Esterases which are inhibited by organophosphates are classified as B esterases. On the basis of studies with purified enzymes, two main classes of B esterases have been established: cholinesterases and carboxylesterases.
