Parkinson’s Linked to Pesticides

Researchers have found a link between pesticide exposure and some cases of Parkinson’s disease. The Los Angeles Times reported that University of California researchers said that “strong new evidence” has found an association between the neurodegenerative disorder and pesticides. Duke University researchers said, “Further investigation of these specific pesticides and others may lead to identification of pertinent biological pathways influencing Parkinson’s disease development,” reported Reuters.

According to the LA Times, the researchers have long believed that pesticides may cause Parkinson’s Disease. Now, experiments prove that chemicals specifically maneb, a fungicide and paraquat, an herbicide”cause Parkinson’s-like symptoms in animals. The LA Times explained that Parkinson’s is a central nervous system disorder that typically affects motor skills and speech, among other functions. While Parkinson’s is not fatal, complications arising from the disease can be deadly, said the LA Times, noting that about 180 in every 100,000 Americans are diagnosed with the disease.

The LA Times said that the California researchers reported in the current issue of the American Journal of Epidemiology and looked at people residing near fields where maneb or paraquat had been sprayed and found that residents were 75 percent likelier on average to develop Parkinson’s. The researchers also found that patients who developed early-onset Parkinson’s (prior to age 60), experienced twice the risk for the disease if exposed to either chemical alone, and four times the risk if exposed to both chemicals, reported the LA Times, adding that generally, the disease followed chemical exposure.

Further reading: Paraquat Herbicide Exposure, Parkinson’s Disease Link, Potential Lawsuits

The California research involved epidemiologist Beate Ritz of UCLA and her graduate student Sadie Costello, now at UC Berkeley, who reviewed the public records of pesticide applications in California’s Central Valley from 1974 to 1999. In collaboration with Myles Cockburn of the University of Southern California, the group developed a tool to estimate pesticide exposure and identified 368 longtime residents who lived within 500 yards of the fields, said the LA Times. The team compared the residents with 341  carefully matched controls who did not live near the fields, said the LA Times. “The results confirmed two previous observations from animal studies. One, that exposure to multiple chemicals may increase the effect of each chemical. That’s important, since humans are often exposed to more than one pesticide in the environment. And second, that the timing of the exposure is also important,” said Ritz, quoted the LA Times.

Meanwhile, Reuters also reported that the results of a family-based,  case control  study of 319 Parkinson’s patients and 200 non-Parkinson’s-affected relatives found that people diagnosed with Parkinson’s disease are more than two times likelier to report pesticide exposure over people not diagnosed with the disease. Dr. Dana Hancock from Duke University, Durham, North Carolina and colleagues concluded that Parkinson’s patients were 61 percent likelier to report direct pesticide application than healthy relatives.

Reuters reported that insecticides and herbicides specifically citing organochlorines, organophosphorus compounds, chlorophenoxy acids/esters, and botanicals were responsible for increased risk of developing Parkinson’s; study results appear in the online journal BioMedCentral (BMC) Neurology.

The Duke University researchers wrote that, “the strongest associations between Parkinson’s disease and pesticides were obtained in families with no history of Parkinson’s. This finding suggests that sporadic Parkinson’s cases may be particularly vulnerable to the toxic effects of pesticides, but the possibility of pesticides influencing risk of Parkinson’s in individuals from families with a history of PD cannot be ruled out,” quoted Reuters.