ABNORMALITIES ON NEUROLOGICAL EXAMINATION AMONG SHEEP FARMERS EXPOSEDTO ORGANOPHOSPHOROUS PESTICIDES

Objectives - Organophosphates are effective pesticides which are frequ ently used in several agricultural settings. Although their acute effe cts are well characterised, it remains unclear whether long term. expo sure can damage the human nervous system. This study sought to investi gate their long term effects by comparing abnormalities on neurologica l examination between groups of markers exposed to and an unexposed gr oup. Methods - 146 exposed sheep farmers and 143 unexposed quarry work ers were recruited into a cross sectional study of symptoms and neurop sychological effects of long term exposure to organophosphates in shee p dip. From a symptom questionnaire given immediately after dipping th e 10 most symptomatic and 10 least symptomatic farmers were selected. Several months later each of these, along with 10 of the unexposed qua rry workers, underwent a standardised neurological examination similar to that which might be used in clinical practice, at a time as remote as possible from recent exposure to organophosphates so as to exclude any acute effects. Results - All 30 selected subjects agreed to parti cipate. The components of the examination which showed a significant d ifference were two point discrimination on the dorsum of the hand (sym ptomatic farmers 22 mm; asymptomatic farmers 13 mm; quarry workers 8 m m) and the dorsum of the foot (symptomatic farmers 34 mm; asymptomatic farmers 10 mm; quarry workers 11 mm), and mean calf circumference (sy mptomatic farmers 35.0 cm; asymptomatic farmers 36.3 cm; quarry worker s 38.6 cm). Overall the prevalence of neurological abnormalities was l ow. Conclusions - The differences in neurological examination detected between groups were subtle and their clinical significance was unclea r. However, they do suggest evidence of an adverse neurological effect from exposure to organophosphates. Further, larger scale studies will be required before it is possible to confirm or refute the difference s detected.