BEHAVIORAL TOXICITY OF ANTICHOLINESTERASES IN PRIMATES - EFFECTS OF DAILY REPEATED SOMAN EXPOSURE

The effects of repeated daily exposure to soman, an organophosphate ne rve agent, on the performance of a well-learned, compensatory tracking task were tested in rhesus monkeys. The ED(50) daily exposure require d to produce a performance decrement on or before the fifth daily expo sure (0.97 mu g/kg) was about 40% of the acute dose required to produc e a similar performance decrement. After repeated, low-dose exposures, performance decrements appeared when serum cholinesterase (ChE) activ ity was inhibited 85-90% Acute exposures that produced similar perform ance effects were associated with lower levels of ChE inhibition (65-7 0%), suggesting that repeated daily exposure may lead to the developme nt of a tolerance (physiological or behavioral) to low levels of ChE a ctivity.