One cause of chronic fatigue syndrome could be exposure to organophosphate pesticides and insecticides. The condition is identical to neuro-behavioural abnormalities noticed since the early 1960s in farmworkers who had been working with sheep dips and insecticides.
These abnormalities, which have never been given a collective name, are identical in onset, symptoms and results of neuroendocrine studies to those suffered by patients with CFS.
To test the theory, Peter Behan of the Institute of Neurological Sciences in Glasgow studied 10 patients suffering from neuro-behavioural symptoms for over a year and who had exposure to organophosphates through a sheep dip from between two and five years. Their symptoms included an acute influenza-like condition followed by incapacitating fatigue. In all cases, there was a long delay between exposure to the pesticides and the onset of the condition.