Abstract
In the early 1960s, researchers noted persistent central nervous system effects in workers who had been chronically exposed to organophosphate (OP) insecticides. A large number of anecdotal reports of neurobehavioural abnormalities in agricultural workers exposed to insecticides and OPs have accumulated since then. In the last few years in Great Britain, there has been increasing interest in farmers who develop neurobehavioural abnormalities. These farmers are identical clinically to patients with typical chronic fatigue syndrome (CFS). The mode of onset, clinical symptoms and results of detailed neuroendocrine studies are identical in both groups. This paper compares and contrasts patients with classical CFS to those with the neurobehavioural syndrome that occurs following delayed chronic exposure to OPs.