02/03/2014 07:04 pm ET | Updated Feb 03, 2014

Pesticides Linked With Increased Parkinson's Risk

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Pesticide exposure could increase the risk of developing Parkinson's disease for people who possess a particular gene variant, according to a new study.

The Neurology study not only showed that Parkinson's risk is increased from exposure to pesticides that inhibit aldehyde dehydrogenase, or ALDH (an enzyme that detoxifies substances in cells), but also that the odds of developing the condition are two to five times higher for people exposed to these pesticides who also possess a variant of the ALDH2 gene.

However, having the ALDH2 gene variant alone does not appear to raise Parkinson's risk -- exposure to the ALDH-inhibiting pesticides needs to also be present. "Parkinson's is a disease that in many cases may require both genetics and environmental factors to arise," study researcher Dr. Jeff M. Bronstein, M.D., Ph.D., of the David Geffen School of Medicine at UCLA and the Greater Los Angeles Veterans Affairs Medical Center, said in a statement.

For the study, researchers examined 360 people with Parkinson's disease and 816 people without Parkinson's disease, as well as their exposure to pesticides at home and work; all the people were from three rural California counties. The researchers identified 11 pesticides that seemed to inhibit ALDH, all of which were used in farming; they divided them up into four classes: organochlorides, dicarboxymides, imidazoles and dithiocarbamates.

The increased risk of Parkinson's came when the person was exposed to the ALDH-inhibiting pesticide at both work and at home. And the more pesticides a person was exposed to, the higher the risk of developing Parkinson's -- people had a 3.5 times higher risk of developing the condition if they were exposed to at least three of the pesticides at home and work.

Certain pesticides seemed to increase risk of Parkinson's more than others; for instance, the pesticide benomyl increased Parkinson's risk 65 percent, while the pesticide dieldrin raised risk six times.

Last year, a review of studies published in the same journal showed that pesticide exposure raises Parkinson's risk by 58 percent. Paraquat, maneb and mancozeb, in particular, seemed to double the risk of Parkinson's, Reuters reported.

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