Study singles out pesticide in Parkinson’s risk
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New research provides more evidence for a link between pesticide exposure and Parkinson’s disease and pinpoints a specific risky chemical.
Dr. Jason R. Richardson of the Robert Wood Johnson Medical School in Piscataway, New Jersey, and his colleagues found that Parkinson’s disease patients were more likely to have detectable levels of beta-hexachlorocyclohexane (beta-HCH) in their blood, and also had higher average levels, than healthy individuals or Alzheimer’s disease patients.
The first evidence suggesting an association between pesticides and the degenerative brain disease Parkinson’s came out in the 1990s, but the current findings are the first to finger a specific chemical, Richardson told Reuters Health.
Beta-HCH belongs to a class of pesticides known as organochlorines, which were banned in the US in the 1970s. But these pesticides can persist in the environment—and in people’s bodies—for decades.
Richardson and his colleagues looked at levels of 16 different organochlorine pesticides in blood samples from 50 people with Parkinson’s disease, 43 healthy people, and 20 people with Alzheimer’s.
Nearly three-quarters of the Parkinson’s patients had detectable amounts of beta-HCH in their blood, compared to 40% of the control patients and 30% of the Alzheimer’s patients. Parkinson’s patients also had a significantly higher level of the pesticide in the blood than the healthy individuals or the Alzheimer’s patients.
And when the researchers divided the study participants into four groups based on their blood levels of beta-HCH, the top quarter was entirely made up of patients with Parkinson’s.
While genetics do play a role in a person’s risk of developing Parkinson’s, known genes account for only 10% of cases of the disease, suggesting that some type of environmental factor may be involved, Richardson said.
A recent study found a “small but significant” link between beta-HCH levels and Parkinson’s disease in people living in the Faroe Islands, who are exposed to very high levels of organochlorine pesticides through their diet of whale blubber and fish, Richardson and his colleagues point out.
The findings suggest that testing beta-HCH levels might potentially offer a way to identify people who are at high risk of Parkinson’s disease, Richardson and his team note. These individuals could then be targeted to receive drugs that protect their brain cells.
“At this point we have no early detection system,” Richardson said. “By the time you get to the clinic there’s so much damage done there’s not much there left to protect.”
SOURCE: Archives of Neurology, July 2009.
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