Pesticide is linked to Parkinson'sBY MICHAEL HANLON SCIENTISTS have found a connection between a common pesticide and Parkinson's disease. The findings that a chemical sprayed on crops could cause severe degeneration in the brain supports claims that Parkinson's is more common in the countryside than in towns and cities. Research results have shown that rotenone can induce the main symptoms of the disease in rats. The pesticide occurs naturally in tropical plants such as the jewel vine, and synthetic versions made in the lab are used by organic farmers. It is used as an insecticide and for killing fish in water management schemes. While the study does not prove that Parkinson's in humans is caused by exposure to this chemical, it provides a link between the illness and the environment. "This shows that 'natural' or 'organic' isn't the same thing as 'safe'," said Professor Tim Greenamyre of Emory University in Atlanta, Georgia. "No one has shown a direct link between rotenone and Parkinson's before. We do not and cannot claim that rotenone is a cause of Parkinson's in humans, but in rats chronic exposure to it is sufficient to cause all the manifestations. "Many pesticides act in exactly the same way as rotenone. Additionally, there are similar toxins produced by other plants and fungi to which we might be exposed." The finding lends credence to the idea that long-term exposure to environmental poisons, including pesticides, may make it more likely that Parkinson's will develop. Parkinson's disease is one of the most common neurodegenerative diseases, affecting about one per cent of all people over the age of 65. Symptoms include problems with movement and severe muscle spasms leading to uncontrolled tremors. The brains of Parkinson's patients contain microscopic protein deposits, called Lewy bodies. Most degenerative brain diseases such as Alzheimer's and Huntingdon's also feature protein deposits in the brain. Although some cases of Parkinson's disease can be attributed to inherited genes, the majority of cases are still unexplained. These so-called sporadic cases, some claim, are caused by environmental factors including toxic pesticides. The main risk factor for Parkinson's disease is age, and more controversially it has also been claimed that the disease is associated with living in the countryside where, presumably, exposure to chemicals like rotenone is more common. A spokesman for the Soil Association, which licenses chemicals to be used by organic farmers in Britain, said rotenone was on the list of approved pesticides, but that it is used "very rarely" in the UK. "In the light of this study, we will be looking very carefully at this substance and may withdraw it from our list," the spokesman added. Professor Adrian Williams, chairman of the medical advisory panel of the Parkinson's Disease Society, said: "It is possible that some people who have a genetic tendency, and get exposed to these pesticides, may damage their brains." The results are published in the current issue of the magazine Nature Neuroscience. |