Parkinson's partially linked to pesticides

UCLA researchers have provided strong new evidence linking at least some cases of Parkinson's disease to exposure to pesticides.  Researchers have suspected for some time that pesticides may cause the neurodegenerative disorder, and experiments in animals have shown that the chemicals, particularly the fungicide maneb and the herbicide paraquat, can cause Parkinson-like symptoms in animals. But proving it in humans has been difficult because of problems in assessing exposure to the agents.

Parkinson's is a disorder of the central nervous system that often impairs the sufferer's motor skills, speech and other functions. It is not fatal of itself, but complications often are. The disease has been recognized since the Middle Ages but became more prevalent in the 20th century. As many as 180 of every 100,000 Americans develop it.

To explore a potential connection to pesticides, epidemiologist Beate Ritz of UCLA and her graduate student Sadie Costello, now at UC Berkeley, studied public records of pesticide applications in California's Central Valley from 1974 to 1999. Every application of pesticides to crops must be registered with the state. Working with Myles Cockburn of USC, they developed a tool to estimate pesticide exposure in areas immediately adjacent to the fields.

They then identified 368 longtime residents who lived within 500 yards of fields where the chemicals had been sprayed and compared them to 341 carefully matched controls who did not live near the fields.

They reported in the current issue of the American Journal of Epidemiology that people who lived next to fields where maneb or paraquat had been sprayed were, on average, about 75% more likely to develop the disease. But those who developed the early-onset form of the disease -- contracting it before the age of 60 -- had double the risk of contracting it if they were exposed to either maneb or paraquat alone and four times the risk if they were exposed to both. In most cases, the exposure occurred years before the onset of the disease. Exposure to other pesticides did not appreciably alter the risk.

"The results confirmed two previous observations from animal studies," Ritz said. "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."

-- Thomas H. Maugh II

Comments

[rob]

FINALLY.

This has been suspected for awhile...perhaps this could at last lead to these chemicals being banned.

[Tasman]

I do hope that the carefully selected control group was controlled for all of the common variables like education, employment history, race, gender, and lifestyle factors (e.g. smoking, drinking, drugs). Too often studies without these controls lead to incorrect conclusions.

Be cautious of the term "may increase" as is used in the last paragraph. The reader should not take this as a "will increase" condition.

[Purple Tentacle]

I am reminded of many years ago, when the DEA used paraquat to poison marijuana farms...

What effect would that have on nearby residents?

[Al]

My father worked for a fertilizer company for many , many years. Like 35 or 40 years between the 40's and 70's. In the later part of his career and life he developed Parkinson's Disease which the family had a strong suspicion was related to his job. I know the fertilizers contained pesticdes and other chemicals which may have affected his health.

[Niels]

Sorry. But this has been documented more than five years ago by a team of Danish scientists. (Due to the personal numbers, the Nordic countries have a unique database on f.i. employment and later illness).

I wonder why it took so long for US researchers to reach the same opinion.

[David Pawlowski]

One of the mysteries of Parkinson's Clusters is the proximity of folks of seemingly different backgrounds who develop the disease despite their young age and good health. This result begs the question could Parkinson's have been triggered by single dose of a chemical compound like Paraquat or a pesticide that was applied incorrectly to food products that ended up poorly washed and then ingested. The famed Parkinson's cluster that Michael J. Fox belongs to is an example of a group of young people who worked in the show biz field and may have enjoyed each other's company at a wrap party where food and drink flowed freely even for those underaged. It would be ironic and sad in the extreme if some Parkinson's clusters were related by the unintentional uptake of chemicals that some tasty (or spiked) brownies contained that someone brought to a party thinking they would give everyone a buzz juse like WoJo's brownies did on the old Barney Miller TV program which no one remembered or could connect years later. It also begs the question how safe is our food these days be it from our nearby fields or from countries that have significant rebel groups who use it as cover for their own traffic?