22
May
Golf Courses Linked to Parkinson’s Disease and Pesticide Use
(Beyond Pesticides, May 22, 2025) A medical study published in the Journal of the American Medical Association (JAMA) finds that “living within 1 mile of a golf course was associated with 126% increased odds of developing PD [Parkinson’s Disease] compared with individuals living more than 6 miles away from a golf course.†While organic land management offers a simple solution, current pesticide restrictions do not address chronic neurological diseases such as Parkinson’s Disease, which are linked to pesticide exposure. It has become increasingly clear that viable and cost-effective land management practices, including for golf course management, are critical to the protection of community health. Yet, the federal regulatory agencies, including the U.S. Environmental Protection Agency (EPA) and U.S. Food and Drug Administration (FDA), do not conduct an alternative practices assessment as part of their review process to determine whether the risks are “reasonable†(statutory language) or the risk assessments accept an unnecessary hazard. The complexity of pesticide exposure, which includes mixtures of multiple chemicals and undisclosed hazardous “inert†ingredients, raises broad questions about the threats to public health as well as biodiversity. See a recent Action of the Week, FDA Must Establish Tolerances for Pesticides Used in Mixtures, to see the potential for FDA to serve a significant role in prompting adequate public health screenings of pesticide products.
Background and Methodology
The research authors are medical professionals at the University of Rochester Medical Center, the University of Kansas Medical Center, Barrow Neurological Institute, and the Mayo Clinic. One of the authors, Ray Dorsey, MD, is a medical practitioner who has written and researched extensively on the underlying mechanisms of the weed killer paraquat (not allowed on golf courses and residential areas) and their adverse health effects, including neurological disorders such as Parkinson’s Disease (PD). (See Daily News coverage of Dr. Dorsey’s research here and here.)
The main objective of this population-based, case-control study was “[t]o assess whether proximity to golf courses is associated with increased PD risk and to use information on groundwater vulnerability and municipal well locations to investigate drinking water contamination as a potential route of exposure.†The patients include 419 PD cases, with incident data and matched controls sourced from the Rochester Epidemiology Project (1991-2015). Patients in this study all had current addresses in Olmstead County; however, they had lived in 22 of the 27 counties in the study region, which the authors signal to aid in accounting for geographical variations in the data.
The avenues of pesticide exposure assessed include “[d]istance to golf courses, living in water service areas with a golf course, living in water service areas in vulnerable groundwater regions, living in water service areas with shallow municipal wells, and living in water service areas with a municipal well on a golf course.†The data for golf course locations were collected from ESRI (Environmental Systems Research Institute) Business Analyst “for 139 golf courses within the 27-county REP [Rochester Epidemiology Project] study region.†Data on groundwater, water service areas, and municipal water wells were collected from the U.S. Geological Survey, the Minnesota Department of Agriculture, and the Minnesota Geospatial Information Office. The methodology for this research was approved by the Mayo Clinic Institutional Review Board, and the associated results are in compliance with the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) reporting guidelines for medical research.
Results
“After adjusting for patient demographics and neighborhood characteristics, living within 1 mile of a golf course was associated with 126% increased odds of developing PD compared with individuals living more than 6 miles away from a golf course ()[,]†say the authors in the Results section of the study. “Individuals living within water service areas with a golf course had nearly double the odds of PD compared with individuals in water service areas without golf courses () and 49% greater odds compared with individuals with private wells (). Additionally, individuals living in water service areas with a golf course in vulnerable groundwater regions had 82% greater odds of developing PD compared with those in nonvulnerable groundwater regions ().â€
Another finding in the study documented that, for individuals living 3 miles from a golf course, the odds of Parkinson’s diagnosis went down 13% on average for every additional mile away from the site. This study builds on existing research identifying the pervasive nature of pesticide contamination from chemical-intensive golf course management.
The authors reference numerous studies that found evidence that various commonly used golf course pesticides leach into groundwater, which is a source of drinking water. (See here, here, here, and here.) One study published in Groundwater Monitoring & Remediation identified 7 pesticides in the groundwater, including the herbicides 2,4-D and chlorpyrifos, with one pesticide in drinking water “at levels more than 200 times greater than the health guidance level.†The authors note that roughly 77% of the patients in this study rely on groundwater resources for their primary source of potable water.
Compounding the threat itself are the endemic barriers to accurate data collection for pesticide contamination in groundwater, leading to the development of an unreliable patchwork of data for groundwater contamination and private wells across U.S. states (See Daily News coverage on how these issues have impacted recent data gathering efforts in Arizona, Connecticut, and Wisconsin.)
Previous Research
Only 15 percent of PD patients have a family history of the disease, which implies that environmental factors—and likely multiple simultaneous culprits—are at fault. Toxicants linked to PD and Lewy Body disease (LBD) include not just paraquat but also organochlorine pesticides, trichloroethylene, and perchloroethylene (largely responsible, along with benzene and vinyl chloride, for the severe water contamination at Camp Lejeune in California), and particulates from fossil fuel air pollution and wildfires. (See Daily News here.) Research co-published by Dr. Dorsey in the Journal of Parkinson’s Disease in 2024 reviewed many studies demonstrating PD’s and LBD’s association with environmental toxicants. “In rural areas,†they write, “the prevalence of PD is almost perfectly correlated with pesticide use.†Just drinking well water and working in agriculture are strongly associated with PD prevalence.
Just last year, bombshell reporting by The New York Times found that one of the world’s largest dementia clusters in young people may be tied to deregulation of pesticides, particularly glyphosate-based herbicides. (See Daily News here.)
For additional coverage on the adverse health and ecological impacts of paraquat, see its dedicated Daily News section here. See here for further studies on Parkinson’s Disease in the Pesticide-Induced Diseases Database.
Update: U.S. Developments on Paraquat and Legal Claims
Last year, in 2024, marked the continuation of numerous campaigns at the state and national levels to ban the weed killer paraquat. U.S. Senator Cory Booker (D-NJ) and six Senators on October 31 called on the U.S. Environmental Protection Agency (EPA) to ban the chemical. Citing that “[f]armworkers and rural residents are disproportionately exposed to paraquat,†the Senators’ letter to EPA stating that, “Paraquat has been linked to Parkinson’s disease, thyroid cancer, and other health harms such as kidney, liver, and respiratory damage, and reproductive harm, including neurodevelopmental impact on developing fetuses [and] [i]n rural areas, exposure to paraquat and other pesticides during pregnancy can increase the risk of leukemia.†Beyond Pesticides, as an extension of engagement with the Ban Paraquat Coalition co-led by the Michael J. Fox Foundation and Environmental Working Group, called on the Biden EPA to ban paraquat following the same criteria it used to ban (without existing stock orders) the registration for the herbicide Dacthal/DCPA in August 2024. (See Daily News coverage on The Dacthal Standard here.)
The New Lede reported in April 2025 that Syngenta, one of the main producers of manufacturing paraquat-based and other pesticide products linked to neurodegenerative outcomes, was forced to settle over 5,000 pending lawsuits claiming paraquat caused their Parkinson’s Disease. Advocates view this as a fearful response to the failure of Modern Agriculture—and Bayer-led effort to shield pesticide companies from failure-to-warn litigation, which legal professionals, including at the National Agricultural Law Center, view as a legal claim that “has become central to pesticide injury litigation.â€
Failure-to-warn claims have been protected by the U.S. Supreme Court’s 2005 decision in Bates v. Dow (2005);Â however, the pesticide industry and their allies are attempting to take them away currently in twelve state legislatures, through EPA rulemaking, and potentially through Appropriations and Farm Bill program negotiations moving into the summer. For more context and resources on corporate immunity battles on failure-to-warn litigation and the intersection with issues of preemption and local authority, see Failure-to-Warn resource hub. The bills are defeated in eight states, signed into law in Georgia and North Dakota, and pending in Missouri and North Carolina. More information is available in the Bills to Track subsection.
In last year’s legislative session, California fell short of banning paraquat, despite the known adverse health effects and disproportionate impacts on farmworker communities in the state. What was initially introduced by Assemblymember Laura Friedman (D-Burbank) in AB 1963 as a full ban on agricultural and nonagricultural uses was whittled down to prompt the California Department of Pesticide Regulation to carry out a complete reevaluation of health risks and determination on its registration status by 2029, a move that EPA was supposed to release in their Final Report on Paraquat Registration in January 2025; however, that was indefinitely postponed following the mayhem in Washington around staffing and capacity at federal agencies. (For additional Daily News coverage, see here.)
Call to Action
The regulatory system has been criticized as corrupt, and it is crucial that advocates understand the challenges they are up against in fighting for a more sustainable and just future. See also Beyond Pesticides’ coverage of paraquat health hazards, regulation, and litigation, as well as our work on conflicts of interest in science, attacks on scientists such as Tyrone Hayes, PhD, and industry influence on federal agencies.
With members of Congress determining spending levels for the 2026 Fiscal Year, now is the time to call on our political representatives to cosponsor and support legislation in support of organic agriculture. (See Action of the Week here.)
All unattributed positions and opinions in this piece are those of Beyond Pesticides.
