Blick D W, Weathersby F R, Brown G C, Murphy M R
Systems Research Laboratories Division of Arvin/Calspan, Dayton, OH 45440.
Pharmacol Biochem Behav. 1994 Jul;48(3):643-9. doi: 10.1016/0091-3057(94)90326-3.
The effects of repeated daily exposure to soman, an organophosphate nerve agent, on the performance of a well-learned, compensatory tracking task were tested in rhesus monkeys. The ED50 daily exposure required to produce a performance decrement on or before the fifth daily exposure (0.97 microgram/kg) was about 40% of the acute dose required to produce a similar performance decrement. After repeated, low-dose exposures, performance decrements appeared when serum cholinesterase (ChE) activity was inhibited 85-90%. Acute exposures that produced similar performance effects were associated with lower levels of ChE inhibition (65-70%), suggesting that repeated daily exposure may lead to the development of a tolerance (physiological or behavioral) to low levels of ChE activity.
