People living within 1 km of an area that had been sprayed with glyphosate were nearly one-third more likely to die from Parkinson’s disease before the age of 75

We first reported on this study in December 2018.
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Study: Potential link between Parkinson's disease and a widely-used herbicide

by Courtney Flatt
OPB, March 12, 2019
https://www.opb.org/news/article/washington-study-glyophosate-herbicide-parkinsons-disease/

One of the country’s most widely-used herbicides could be linked to an increase in early deaths from Parkinson’s disease for people who live near farmlands, according to new research in Washington.

Parkinson’s is a neurodegenerative disease that causes muscles to stop functioning properly. There are no known cures.

New research conducted in some of Washington’s most productive agricultural regions suggests glyphosate, the active ingredient in the popular herbicide Roundup, could be linked to more people dying from Parkinson’s disease before they turn 75.

“I remember sitting in the office, and I think we were all looking at each other and thinking, ‘Wow, that’s serious,’” said Mariah Caballero, the study’s lead author.

The research team studied land-use maps from the U.S. Department of Agriculture that showed agricultural chemical applications and death data from the Washington Department of Health. In some cases, the researchers found that people living within 1 kilometer of an area that had sprayed glyphosate were nearly one-third more likely to die from Parkinson’s disease before reaching the age of 75.

Caballero, a senior at Vassar College, conducted the research at Washington State University’s Community Health and Spatial Epidemiology Lab. The study was published in the International Journal of Environmental Research and Public Health.

“It’s very important to say, we don’t think there is any causation here. We’re just observing and seeing a relationship. There’s something here we need to investigate more,” said Ofer Amram, an assistant professor at the Washington State University College of Medicine and study co-author.

The researchers examined data of more than 4,600 people who had died from Parkinson’s in Washington. According to their published report, “several clusters of premature deaths were found in highly agricultural areas” in parts of Yakima and Douglas counties east of the Cascades, and Whatcom County in northwestern Washington. All three counties contain some of Washington’s more productive farmland.

In one section of Douglas County, they found a large cluster of people who died early because of Parkinson’s and lived within 1 kilometer of glyphosate application. In Yakima County 18 of the 22 deaths studied were within 1 kilometer of glyphosate application.

“It aligns fairly well with agricultural land. Generally, that’s in Eastern Washington because cropland and agriculture, in general, is centered there,” Caballero said.

The researchers looked at other agricultural chemical applications, including Atrazine, Diazinon and Paraquat.

The herbicide Atrazine and the insecticide Diazinon did not appear to be linked to premature deaths from Parkinson’s disease.

The herbicide Paraquat showed a slight increase in early deaths. When the researchers looked at all pesticides applied to cropland, they also saw a slight increase in premature deaths from Parkinson’s.

Of the early deaths the researchers studied, 93 percent were classified as non-Hispanic white, and 71 percent were male. The average age of death was 71 years old, as opposed to 85 years old for people who were diagnosed with Parkinson’s later in life.

A spokesperson for Bayer Crop Sciences, which merged with Monsanto Co. last year, said in an emailed statement that there is no evidence that glyphosate causes Parkinson’s disease. The company cited a 2011 study that found no link between glyphosate use and Parkinson’s. Glyphosate is the active ingredient in Monsanto’s Roundup herbicides.

“The authors of this study didn’t confirm whether their patients had even been exposed to glyphosate or that crops nearby had even been sprayed with glyphosate,” spokesperson Charla Lord said.

For her part, Mariah Caballero said herbicide and pesticide application data isn’t made available for researchers to work with right now.

“(In the study) we’re unable to specifically say that this pesticide was applied at this time, and how many times. But I think that also speaks to the record keeping that’s happening right now,” Caballero said. “I think that’s something that’s important — that we have the data to understand and analyze these things. Using land-use data is a proxy.”

She said it’s important that people know about the risks of glyphosate exposure, as well as when and where it’s being sprayed in agricultural areas.

Caballero grew up surrounded by Eastern Washington cropland, which is why she said wants people to have more scientific information.

“I absolutely understand the importance of farming and the importance that glyphosate plays in that realm. But I also really care about the health of communities, like my own, that often cannot advocate for themselves,” she said.

The publisher of the research, the Journal of Environmental Research and Public Health, has received criticism in the past for a lack of rigor in some of its articles, as well as for its number of retractions and corrections.

Despite such concerns, researchers at WSU said they are standing by the study and its publication in the Journal of Environmental Research and Public Health. Ofer Amram, a professor at the Elson S. Floyd College of Medicine, said the researchers published the study in an open access journal because it gives more people the opportunity to see the information.

“I think it’s a fine journal. It’s not the top of the top. One of the reasons this article is not in a top-of-the-top journal is because it’s exploratory. It doesn’t have a definitive answer, and we’re not claiming to have a definitive answer. We are taking secondary data, and we acknowledge its limitations,” Amram said.
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Estimated Residential Exposure to Agricultural Chemicals and Premature Mortality by Parkinson’s Disease in Washington State
Mariah Caballero, Solmaz Amiri, Justin T. Denney, Pablo Monsivais, Perry Hystad, and Ofer Amram
Int. J. Environ. Res. Public Health 2018, 15(12), 2885; https://doi.org/10.3390/ijerph15122885
https://www.mdpi.com/1660-4601/15/12/2885

Abstract
The aim of this study was to examine the relationship between estimated residential exposure to agricultural chemical application and premature mortality from Parkinson’s disease (PD) in Washington State. Washington State mortality records for 2011–2015 were geocoded using residential addresses, and classified as having exposure to agricultural land-use within 1000 meters. Generalized linear models were used to explore the association between land-use associated with agricultural chemical application and premature mortality from PD. Individuals exposed to land-use associated with glyphosate had 33% higher odds of premature mortality than those that were not exposed (Odds Ratio (OR) = 1.33, 95% Confidence Intervals (CI) = 1.06–1.67). Exposure to cropland associated with all pesticide application (OR = 1.19, 95% CI = 0.98–1.44) or Paraquat application (OR = 1.22, 95% CI = 0.99–1.51) was not significantly associated with premature mortality from PD, but the effect size was in the hypothesized direction. No significant associations were observed between exposure to Atrazine (OR = 1.21, 95% CI = 0.84–1.74) or Diazinon (OR = 1.07, 95% CI = 0.85–1.34), and premature mortality from PD. The relationship between pesticide exposure and premature mortality aligns with previous biological, toxicological, and epidemiological findings. Glyphosate, the world’s most heavily applied herbicide, and an active ingredient in Roundup® and Paraquat, a toxic herbicide, has shown to be associated with the odds of premature mortality from PD.