AAN

AAN 2024: Pesticide use linked to Parkinson's in Rocky Mountain, Great Plains Region

March 26, 2024

Use of 14 pesticides from 1992 to 2008 was strongly associated with Parkinson's disease (PD) risk in rural counties in the Rocky Mountain and Great Plains region, according to an abstract from a study involving 21.5 million Medicare beneficiaries that will be presented at the American Academy of Neurology's annual meeting April 13-18 in Denver.

Three pesticides in particular—simazine (an herbicide), lindane (a recently banned insecticide), and atrazine (an herbicide)—had the strongest relationship with PD, the fastest-growing neurological disorder in the world.

• The study involved a review of records from the 21.5 million people enrolled in Medicare in 2009 (aged 67+ in 2009) to determine the rate of PD for various regions across the country.
• Researchers reviewed data from parts of Colorado, Idaho, Kansas, Montana, Nebraska, Nevada, New Mexico, North Dakota, Oklahoma, South Dakota, Texas, Utah and Wyoming.
• The researchers then looked for a possible relationship between rates of PD and use of 465 pesticides between 1992 and 2008 obtained from county-level United States Geological Survey estimates.
• Researchers mapped the nationwide association for 65 pesticides (those with sufficient data) using Multiscale Geographic Weighted Regression (MGWR), and classified pesticides according to the strength and ratio of positive to negative regression coefficients.
• Researchers identified 14 pesticides strongly associated with PD in the Rocky Mountain and Great Plains region. Of these, simazine, lindane, and atrazine had the strongest relationship with PD.
• Counties with the highest decile of herbicide simazine application had a 36% (95% CI, 32%-41%) greater relative risk of PD compared to counties with the lowest decile of exposure.
• In the counties with the highest exposure to simazine, 411 new Parkinson’s disease cases developed per every 100,000 people compared to 380 cases in counties with the lowest exposure.
• For the herbicide atrazine and insecticide lindane, relative risks were 31% (95% CI, 26%-35%) and 25% (95% CI, 21%-29%) greater for counties in the top decile of application compared to the lowest decile, respectively.
• There was a modest dose-response relationship between PD risk and all three pesticides.

Sources:

Lapadat A, et al. Application of simazine, atrazine, and lindane pesticides are associated with incident Parkinson's disease risk in the Rocky Mountain region. Presented at: 2024 American Academy of Neurology 76th Annual Meeting; April 13-18; Denver, CO. https://aanfiles.blob.core.windows.net/aanfiles/a9aeceda-f16d-4adb-87aa-22eae1f87091/2024%20AAN%20Annual%20Meeting%20Abstract%20-%20Pesticides%20and%20Parkinson%27s

(2024, February 27). American Academy of Neurology. Study finds pesticide use linked to Parkinson's in Rock Mountain, Great Plains Region. [Press release]. https://www.aan.com/PressRoom/Home/PressRelease/5149