Is It Possible to Have Nerve Agent Effects from Exposures That Are Unrecognized?
Based on the published literature, the possibility cannot be ruled out, for the following reasons: It is well documented that occupationally exposed persons were found who reported no acute signs and symptoms and who had very low cholinesterase levels (Gaon and Werne, 1955; Holmes, 1959; Freeman et al., 1956). Such persons were not subject to any special follow-up but in some cases were observed to be asymptomatic during the period when their cholinesterase levels were returning to normal. Some of these individuals could have become tolerant of the agent as a result of their exposures. Similar situations are documented in organophosphate pesticide workers, in whom tolerance without preceding symptoms was found (Hayes, 1982). It is not certain that tolerance is without ill effects, but the situation is little studied. A clinical effect in tolerant persons and animals is an increased sensitivity to atropinelike anticholinergic drugs. Although tolerance has been demonstrated in humans, th
