ELEVATED QUANTITATIVE VIBROTACTILE THRESHOLD AMONG WORKERS PREVIOUSLYPOISONED WITH METHAMIDOPHOS AND OTHER ORGANOPHOSPHATE PESTICIDES

To evaluate chronic effects of acute organophosphate pesticide poisoni ng, quantitatively determined vibrotactile thresholds were measured as an index of peripheral neuropathy among agricultural workers in Nicar agua. Thirty-six male workers were evaluated between 10 and 34 months after hospitalization for acute organophosphate poisoning and compared to an age- and sex-matched community reference group. Vibrotactile th resholds were measured quantitatively in right and left index fingers and right and left great toes. Study subjects were stratified into thr ee groups: 1) never poisoned; 2) poisoned with organophosphates other than methamidophos, agents which have not been reported to cause perip heral neuropathy; and 3) poisoned with methamidophos, a peripheral neu rotoxin. For all digits, there was a statistically significant trend o f increasing age- and height-adjusted thresholds across these three ex posure categories. Over one fourth of patients previously poisoned wit h methamidophos we studied had abnormal vibrotactile thresholds. These results suggest that previously reported cases of organophosphate-ind uced delayed polyneuropathy may represent only the worst disease in a spectrum of impairment, a sequela of exposure that may be much more co mmon than previously thought. (C) 1994 Wiley-Liss, Inc.