Elevated quantitative vibrotactile threshold among workers previously poisoned with methamidophos and other organophosphate pesticides.
McConnell-R; Keifer-M; Rosenstock-L
Am J Ind Med 1994 Mar; 25(3):325-334
A study of vibrotactile sensitivity in Nicaraguan agricultural workers previously poisoned with methamidophos (10265926) and other organophosphorus pesticides was conducted. The cohort consisted of 36 males, 15 to 44 years old, who had been discharged from a hospital in the Northern Pacific Coastal Plain of Nicaragua for organophosphate insecticide poisoning between July 7, 1986 and July 31, 1988. The comparisons consisted of 36 age matched friends or siblings from the same community as the cohort who had never been treated for pesticide poisoning. The subjects completed a questionnaire to obtain information on demographic characteristics and medical history focusing on previous poisonings. Vibrotactile thresholds of the right and left index fingers and big toes were measured in May or June 1989 with the Vibraton-II apparatus. Callus thicknesses on these digits were also measured. Twenty one patients were classified as being poisoned by methamidophos. Fifteen reported being poisoned by other organophosphates such as acephate (30560191), chlorpyrifos (2921882), or malathion (121755). The prevalence of moderate or thick callus formation in one or more big toes was significantly greater in the patients than in the comparisons. There were too few subjects with upper extremity calluses for analysis. The prevalence of abnormally elevated vibrotactile thresholds in the right and left index fingers and big toes in the patients poisoned by methamidophos was 9.5, 4.8, 24, and 29%, respectively. The prevalence of abnormally elevated vibrotactile thresholds in these digits in patients poisoned by other pesticides was 6.7, 6.7, 13, and 27%, respectively. The prevalence of abnormally elevated vibrotactile thresholds in the same digits in the comparisons was 0, 0, 5.9, and 5.9%, respectively. After adjusting for callus thickness, the prevalence of elevated vibrotactile thresholds across all digits was significantly higher in the patients poisoned by methamidophos than in those poisoned by other organophosphate pesticides and the comparisons. The authors conclude that methamidophos poisoning causes chronic sensory impairment. They recommend that use of methamidophos be substituted by other pest control methods that do not have the potential to cause peripheral neuropathy.
Neurotoxic-effects; Organo-phosphorus-pesticides; Occupational-exposure; Insecticide-poisoning; Agricultural-workers; Sensory-thresholds; Epidemiology; Neurotoxicity;
Author Keywords: neuropathy; pesticide poisoning; index fingers; great toes; methamidophos; vibrotactile thresholds; organophosphate; Nicaragua
Community Medicine Mount Sinai School of Medicine One Gustave L. Levy Place New York City, NY 10029-6754
10265-92-6; 30560-19-1; 2921-88-2; 121-75-5
American Journal of Industrial Medicine
Division of Environmental and Occupational Medicine, Department of Community Medicine, Mount Sinai School of Medicine, New York, New York