Scientists link low level OP use to neurological damage
SCIENTISTS have found that low-level exposure to organophosphates (OPs) results in lasting damage to human health.
The link between OPs and human health has been one of the most controversial issues for decades. Hundreds of farmers have complained of ill health after using OP products, particularly sheep dips, since the 1970s and 1980s.
Between 1985 and 1998 more than 600 reports of ill health following exposure to sheep dip were received by a government adverse reaction surveillance scheme. This includes a number who were following a Government requirement to dip sheep in pesticide formulations containing OPs between 1988 and 1991.
While the toxic effects of high level OP poisoning have been long-established, proof of the effects of low-level exposure has been harder to establish.
But now a systematic review of the literature carried out by researchers at UCL, in London and the Open University, has found that low exposure to the chemicals damages ‘neurological and cognitive function’.
The scientists found that memory and information processing speed were affected to a greater degree than other cognitive functions such as language.
Lead author Dr Sarah Mackenzie Ross said: “The analysis reveals that the majority of well-designed studies undertaken over the last 20 years find a significant association between low-level exposure to organophosphates and impaired cognitive function.”
The research, published in the journal Critical Reviews in Toxicology, used meta-analysis, which combines the results of several studies to create an overview of a body of literature. Dr Mackenzie Ross said the research was the first attempt at a quantitative evaluation of the data assimilated from 14 studies and more than 1,600 participants.
The researchers said pesticides ‘prevent millions of people from starving to death and from contracting disease, but they are also harmful to humans under certain circumstances’.
As well as sheep farmers, Gulf War Veterans, who were exposed to pesticides on a daily basis during their tour of duty, and airline pilots and cabin crew, who can be exposed to OPs in engine oil, have also complained that their health has been damaged by the chemicals.
But attempts to establish firm proof of low level poisoning have proved frustrating for people affected by OPs and those campaigning on their behalf.
“In the UK a number of occupational groups have expressed concern that their health has been affected by exposure to organophosphates,” said Dr Virginia Harrison, of the Open University.
The researchers said they hoped their findings would be of interest to Government advisory committees and departments who are currently reviewing the neurotoxicity of low level exposure to OPs.
Derived from World War II nerve gas agents, OP pesticides are the most widely used insecticides in the world, with extensive use in agriculture, in the military and for domestic purposes.
The World Health Organisation (WHO) said OPs were ‘one of the most hazardous pesticides to vertebrate animals, responsible for many cases of poisoning worldwide’.