Paraoxonase polymorphisms and self-reported chronic ill-health in farmers dipping sheep.

BACKGROUND Serum paraoxonase (PON1) provides protection against organophosphate induced toxicity. Recently we reported that the frequency of paraoxonase polymorphisms in sheep dippers with self-reported chronic ill-health differed from that in dippers with a similar dipping history but no ill-health. As these analyses may have included subjects with conditions unrelated to organophosphate exposure, the aim of this study was to examine whether the risk associated with PON1 polymorphisms varied using a more homogenous case and referent population. METHODS Each subject completed a detailed symptom questionnaire and their general practitioner was asked whether there was any history of neurological disease that could be confused with the effects of organophosphate poisoning. Subjects were then excluded both on clinical grounds and where identified as atypical on discriminant analysis. RESULTS Risk associated with the PON1 192 and 55 genotypes altered little with these changes in the population. CONCLUSIONS These findings are consistent with the hypothesis that organophosphates contribute to the self-reported ill-health of sheep dippers.