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Recently, one of my relatives, who is a farmer, got diagnosed with Parkinson's Disease. He is 45 years old and has no positive family history.

One of the doctor told us that the occurence of the disease could be explained by his daily exposure to pesticides while another one refuted this theory due to a lack of proper "evidence".

I am a little bit lost with these statements as several members of our family are still working as farmers and we are concerned about getting the disease too.

My question: is there any proven link between Parkinson's Disease and pesticide exposure?

Thank you in advance for your help.

  • Parkinson's Disease has been happening to old people for thousands of years, long before pesticides even existed. A person living in a city or suburb is just as likely to get Parkinson's as a rural farmer. – Tyler Durden Aug 3 '16 at 15:59
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    @Tyler Any scientific evidence for those claims? – Lucky Aug 4 '16 at 11:24
  • I think it would be nice to have a "parkinson" tag. I don't have enough reputation so could someone with enough reputation (at least 150) create one? This would be very useful. Thank you very much in advance. – Richard Callahan Aug 4 '16 at 12:32
  • @Tyler Durden. Ok might perhaps be true for older individuals. But in my case, my relative is not that old and probably has a so called Young Onset Parkinson Disease (so not a "typical" PD which occurs in the elderly). This is why, because of his negative family history, one of the doctor suggested environmental exposure (in our case pesticide) as possible explanation. But anyway, thank you for your suggestion. – Richard Callahan Aug 4 '16 at 12:36
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    @Richard Callahan: good suggestion. I have created a "parkinson" tag. Hope this helps for future questions! Best wishes. – S.Victor Aug 9 '16 at 20:29
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Yes (ish), this meta-analysis proved a strong correlation between exposure to pesticides and likelihood of developing Parkinson's. Note, there is no direct X level of exposure leads to Y likelihood, just a strong correlation.

"Although the risk of PD increased with increased duration of exposure to pesticides, no significant dose-response relation was established, and no specific type of pesticide was identified. Our findings suggest that exposure to pesticides may be a significant risk factor for developing PD"

A meta-analysis of Parkinson's disease and exposure to pesticides. Priyadarshi A, Khuder SA, Schaub EA, Shrivastava S. Neurotoxicology. 2000 Aug;21(4):435-40.

A more recent meta-analysis reviewed the aforementioned meta-analysis and while criticising some of the limitations of the study (in particular the heterogeneity of the included trials) concluded:

The literature supports the hypothesis that exposure to pesticides or solvents is a risk factor for PD. Further prospective and high-quality case-control studies are required to substantiate a cause-effect relationship. The studies should also focus on specific chemical agents.

(Pezzoli G et al. Exposure to pesticides or solvents and risk of Parkinson disease. Neurology. 2013 May 28;80(22):2035-41. doi: 10.1212/WNL.0b013e318294b3c8.)

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    Hi @JJosaur. I can only second your answer. Nevertheless, maybe it would be worth adding a more recent meta-analysis published on this topic to your answer? (Pezzoli G et al. Exposure to pesticides or solvents and risk of Parkinson disease. Neurology. 2013 May 28;80(22):2035-41. doi: 10.1212/WNL.0b013e318294b3c8.) I think it would be interesting as it basically comes to the same conclusion as the study by Priyadarshi et al while also addressing some of the limitations associated with this study (in particular the heterogeneity of the included trials). Best wishes. – S.Victor Aug 4 '16 at 10:43
  • You are welcome. When I saw some of the comments questionning the possible link between PD and pesticides, I thought it might be necessary to bring some additional references... Best wishes. – S.Victor Aug 4 '16 at 10:56
  • Thank you JJosaur and @S.Victor for your precious answers and insights. It really helps a lot! – Richard Callahan Aug 4 '16 at 12:39
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Not directly about pesticides but I have years ago read that Parkinson's is post-Industrial Revolution disease -- that is, it started to be observed once coal started to be used in large quantities for powering industrial furnaces and engines. One could argue that the increase in life span that occurred at around the same time might be responsible for cases being observed then or simply that doctors only began to diagnose it around then but firstly, people have throughout history lived into old age and secondly, it is very plausible (to me, anyway) that anything that is neurotoxic, including particulates in coal smoke/mercury liberated by burning of coal, contributes to many neurological diseases including Parkinson's. Of course, many insecticides by design are neurotoxic to insects and were based on nerve gases developed for use on humans.

EDIT: https://www.loe.org/shows/segments.html?programID=97-P13-00033&segmentID=1 https://www.poison.org/articles/2010-jun/pesticide-and-nerve-agent-commonality

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    Welcome to MedicalSciences.SE. We work differently than most SE sites in that we have a strict policy that all answers should be backed up with reliable references so that the answer can be independently verified regardless of the reader's background. See this list of reliable sources. If you still have trouble with this, feel free to visit the help center or Medical Sciences Meta. Unreferenced claims can lead to answers being deleted. – Carey Gregory Feb 23 '19 at 18:36
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    @CareyGregory: I hope the links I added help. It is well-known that modern insecticides have a research history linked to nerve agents. That Parkinson's was only diagnosed after the advent of the Industrial Revolution perhaps less so. – releseabe Feb 23 '19 at 19:11

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