Nature Medicine | Spoonful of Medicine

Bug and weed killers kick Parkinson’s disease in gear

4518790585_7c71144f5b_m.jpgSince the early-1990s, scientists have known that farmers and other field workers are more likely to succumb to Parkinson’s disease because of their exposure to pesticides and other agricultural chemicals. But these studies fell short on showing a causal relationship between pesticides and the debilitating neurodegenerative disorder.

So, researchers turned to rodent models to prove the link. In the last decade, researchers found that three bug and weed killers promoted neurodegeneration in mice. And now, an independent team has validated those findings in a large epidemiological survey in humans.

The team led by Beate Ritz, an epidemiologist at the University of California–Los Angeles, estimated the average 25-year pesticide exposure for around 700 Californians, about half of whom developed Parkinson’s. Reporting in the European Journal of Epidemiology, the researchers found that people who lived or worked near farmlands treated with two commonly used agricultural fungicides — ziram and maneb — as well as the herbicide paraquat were three times more likely to develop Parkinson’s disease than those Parkinson’s disease than those were not exposed to these agricultural chemicals.

The results follow a previous study of residents from California’s Central Valley showing that people who lived near fields treated by two of these chemicals were 75% more likely to get Parkinson’s.

The findings “suggest that the critical window of exposure of toxicants may have occurred years before the onset of motor symptoms when the diagnosis of Parkinson’s disease is made,” Ritz said in a statement.

Looking ahead, Ritz and her colleagues urge lawmakers to establish monitoring programs to estimate pesticide exposure in rural communities in hopes of limiting people’s exposure to these agricultural chemicals and, ultimately, of getting Parkinson’s disease.

Image: Santiago Nicolau, Flickr Creative Commons


  1. Report this comment

    Cheryl Fontaine said:

    Pesticides and herbicides – dumping poison into the ground, waterways, the air. Did anybody really believe that wasn’t going to do irreparable damage? And yet the poisoning goes on – responsible for untold illnesses in humans, annihilation of vast numbers of bee colonies, eradication of frogs and other amphibians, destruction of millions of bats, birds, beneficial insects, fish and other forms of wildlife in the food chain.

    Yet they just keep letting them pour it all over us.

    Rachel Carson’s ‘Silent Spring’ should be a first grader primer. Required reading. More important than even the Bible. This is our home, the only one we have, and Greed has bought its destruction.

  2. Report this comment

    Sherman said:

    One of the major problems with pesticide exposure studies is the long delayed period in between exposure and the onset of an illness. Other challenges are identifying definitive dose and exposure route (lung, skin, GI) associating with an illness. Therefore, often times, we tend to react (retrospectively) to such exposure findings than proactively preventing exposure risks. This study reconfirms the concerns about the use of pesticides. With this study and previous understanding of risks (at least from studies with mice), safer, less toxic pesticides (and more organic methods) are urgently needed for agricultural use.