14 January 2005James Meikle, health correspondent
The government's independent scientific advisers are stepping up the pressure on Whitehall to investigate the long-standing fear that the widespread use of pesticides against fungi, insects and weeds has increased risk of disease in humans.
Their demand for studies to show whether and how the chemicals may cause the nervous system disorder Parkinson's disease coincides with a separate call for improved measures of exposure to pesticides, because of possible links with prostate cancer.
The Department of Health's committee on carcinogenicity has stopped short of calling for new research on prostate cancer, but wants better monitoring of chemical use.
The advisory committee on pesticides recommends laboratory research into the toxic mechanisms that might be involved in Parkinson's.
It says it would be "useful" to set up long-term health studies of workers making or using pesticides, to see whether they replicate the association found in other countries between chemical exposure and incidence of the disorder.
Years of research into Parkinson's has not discovered what causes nerve cells to die in a part of the brain called the substantia nigra. Ageing is a prime factor but a combination of genes and pollutants or pesticides is believed to be the trigger.
Studies have so far failed to find a definite relationship with well-water drinking, farming, rural living, and pesticide exposure, but scientists at Aberdeen University, and in Finland, Romania, Italy and Malta are nearing the end of a EU-funded study investigating some of these factors.
The pesticides committee concluded in November, in a so-far unpublicised finding, that a review of the existing evidence indicated a correlation between pesticides and Parkinson's but "did not point to a particular toxic mechanism or a hazard from a specific compound or group of compounds".
The review by the Medical Research Council's Institute of Environment and Health found significant gaps in research and suggested new work to take into account the fact that the exposure to pesticides in Britain might be different to that in other countries, because of differences in agriculture, climate and regulations.
If there was enough historical information, it would be helpful to discover whether the incidence and prevalence of Parkinson's had changed substantially in the past 50 years.
Elizabeth Sigmund of Opin (Organophosphates Information Network) said a high proportion of those on its database had complained of symptoms like Parkinsonism, the group of disorders to which Parkinson's belongs.
"The government has been disgracefully dilatory. It knows farmers have been exposed to a variety of toxic chemicals. It is high time it took research very seriously and thought about how it can compensate people who are obliged to use such chemicals. I think there is beginning to be a sea-change in attitudes."
Linda Kelly, chief executive of the Parkinson's Disease Society, said that if scientists could understand how the disease was triggered, "you could perhaps understand what causes Parkinson's in the first place, and that could deliver better treatments".
The food and environment department, Defra, said some studies had found no association between pesticide use and Parkinson's, but added: "A link between pesticides exposure and Parkinson's disease cannot be discounted based on the evidence currently available. That is why further research is required."
The pesticides safety directorate was investigating the best way forward.
http://society.guardian.co.uk/print/0,3558,5103155-105965,00.html
