Defra - Department for Environment, Food and Rural Affairs.

Science Search

Science and Research Projects

Return to Science Search homepage   Return to Project List

A case-control study of neuropsychological and psychiatric functioning in sheep farmers exposed to OP pesticides - VM02126

Since the 1950’s there has been an increasing use of organophosphates (OPs) in agriculture, industry and for domestic purposes. Concern has been growing about the problem of intoxication in those repeatedly exposed to OPs, particularly during farming operations. The acute effects of over-exposure to organophosphates are well known and are secondary to inhibition of the enzyme acetylcholinesterase. However, there is disagreement about whether prolonged low level exposure, in the absence of a history of acute intoxication, can cause ill health. In 1998 a working party (COT) was commissioned by the UK Government to review the available scientific evidence concerning the potential toxicity of low level exposure to organophosphate pesticides. They focussed on five health outcomes including peripheral neuropathy and neuromuscular dysfunction, autonomic nervous system dysfunction, EEG abnormalities, psychiatric disease and neuropsychological abnormalities. With regard to the latter, evidence exists to support the view that neuropsychological abnormlaities can occur as a long-term consequence of acute OP poisoning, but COT consider that further research is required to determine whether low level exposure to OPs causes disabling neurological or psychiatric disease in a small sub-group of exposed persons. They recommend that any study designed to address this issue allow for the fact that individuals with disabling disease may have retired from work (or be employed in a different capacity); and studies should explore the factors which may render some individuals at increased risk of clinically significant disease.This study will establish whether low-level exposure to OPs causes disabling neurological or psychiatric disease in a small subgroup of agricultural workers. It will be the first study to examine individuals who have retired on ill health grounds and to determine whether they constitute a particular subgroup of individuals who are more susceptible to the effects of OPs because of their exposure, psychosocial or medical history.
Project Documents
• Final Report : VM02126 - Final report   (252k)
Time-Scale and Cost
From: 2004

To: 2006

Cost: £222,100
Contractor / Funded Organisations
University - London - University College
Animal Health              
Plants and Animals              
Sheep Dipping              
Veterinary Medicines              
Fields of Study
Animal Health
Veterinary Medicine