Abstract
The results of 2 postal questionnaire surveys on neuropsychiatric symptoms in individuals potentially or actually exposed to organophosphates are reported. One demonstrates significantly increased (p < 0.0001) symptomatology in exposed versus non-exposed farmers. The second shows essentially identical symptom patterns between those exposed through sheep dipping and those exposed in other ways. Taken together, we suggest that this work provides powerful evidence in favour of a causal relationship between organophosphate exposure and significant neuropsychiatric disorder including mood destabilization and cognitive impairment.