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Pesticides: A Link to Parkinson's?

Researchers Say Pesticide Exposure and Head Trauma Are Factors in Parkinson's Disease
By
WebMD Health News
Reviewed by Louise Chang, MD

Parkinson's Pesticides Head Trauma

May 30, 2007 -- Boxing and agricultural work seemingly have little in common, but new research suggests both occupations are linked to an increased risk for Parkinson's disease.

The findings add to the evidence implicating pesticide exposure and repeated head trauma as likely contributors to Parkinson's disease and related degenerative brain disorders.

Farm workers and other study participants who reported high levels of pesticide exposure were found to have a 41% increased risk of developing Parkinson's disease compared with participants who reported no pesticide exposure.

And having been knocked unconscious more than once was associated with a 2.5-fold increase in Parkinson's risk, compared with having never been knocked out.

The findings suggest that at least some of the causes of Parkinson's disease and related disorders are modifiable, but more research is needed to better understand this association, researcher Finlay Dick, MD, of the Scotland's University of Aberdeen, tells WebMD.

"One limitation of this study and most others is that people could not recall which pesticides they had been exposed to," he says. "So we weren't able to tease out which specific pesticides might be behind the effect we observed."

Parkinson's disease is a progressive disease of the brain that affects balance and the body's ability to coordinate muscles and move.

Lifetime Exposure Evaluated

The European Commission-funded study included 959 patients with Parkinson's disease and closely linked neurological disorders and 1,989 people without any evidence of the degenerative disorder living in Scotland, Italy, Sweden, Romania, or Malta.

All study participants completed a questionnaire designed to determine their lifetime occupational and recreational exposure to pesticides, chemical solvents, and the metals iron, copper, and manganese.

Researchers also gathered information on family history of Parkinson's disease and history of head trauma leading to unconsciousness.

Reported exposures to chemical solvents or the metals iron, copper, and manganese were not found to influence Parkinson's risk, but even minimal exposure to pesticides was associated with a small increase in risk.

The findings were published May 30 in an online issue of the journal Occupational and Environmental Medicine.

Identifying Specific Pesticides

The European study is not the first to link pesticide use to an increased risk for Parkinson's disease, or to suggest that risk increases as exposures increase.

Earlier this year, researchers from the National Institute of Environmental Health Sciences (NIEHS) also reported that lifetime exposure to pesticides was associated with an increased risk for the disease.

Freya Kamel, PhD, who led that study team, is conducting related research designed to identify the specific pesticides associated with risk.

She tells WebMD that she expects to publish findings from the study within a year or two.

"We have some ideas about which pesticides or pesticide classes are involved, but this will be a more detailed look at the issue," she says.

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