Abstract 16: Effect of chronic occupational organophosphate exposure on peripheral nerves among filipino ricefield workers.

Abstract

Objectives: To investigate whether chronic occupational exposure to organophosphates among ricefield workers in a rice institute is related to electrodiagnostically detectable measures of multiple peripheral neuropathy, that is, to investigate whether rotation in areas of work would improve the conduction velocities of those workers found to have peripheral neuropathy, after being shifted from an exposed to a nonexposed status in their work. Design: A 2-year prospective research. Setting: Academic medical center. Participants: 24 male workers with exposure to organophosphates and a well-matched control group of 64 men from the general population who were not exposed to organophosphates. Interventions: All participants in the study and control groups were tested electrodiagnostically for peripheral neuropathy work-up. Those positive for peripheral neuropathy in the study (exposed) group were rotated from their field of work to a nonexposed status for 1 year. A repeated electromyographic nerve conduction velocity test was conducted after 1 year in all participants in the study group. Main Outcome Measures: The chi-square test was used to determine the association between exposure to organophosphate and multiple peripheral neuropathy. The Wilcoxon signed-rank test was used to test for differences in the electrodiagnostic data for the years 2001 and 2002. Results: 6 of 24 participants in the study group had multiple peripheral neuropathy, while 20 of 64 participants in the control group had multiple peripheral neuropathy ( P=.707). Only 4 cases of those diagnosed with peripheral neuropathy in 2001 improved in nerve conduction velocities in their repeat testing in 2002 ( P=.096). Level of statistical significance was set at .05. Conclusions: The results failed to show an association between chronic occupational organophosphate exposure and multiple peripheral neuropathy. Likewise, the nerve conduction velocities of those workers with peripheral neuropathy did not improve 1 year after being shifted from an exposed status to a nonexposed status.