A US study has found people living near golf courses face significantly higher odds of developing Parkinson’s disease, with the greatest risk among those living within just one to three miles (about 1.6-4.8 km). Researchers linked the increased risk to potential pesticide exposure via groundwater and air, particularly in areas where golf courses draw from vulnerable aquifers.
The findings have added fuel to calls from Australian neurologists and advocates urging the federal government to ban paraquat – a widely used herbicide still permitted on farms and turf, despite its known neurotoxicity and bans in over 70 countries.
The population-based case-control study, published in JAMA Network Open [link here], tracked more than 5,500 residents in Minnesota from 1991 to 2015, comparing 419 Parkinson’s cases against over 5,000 matched controls. It found that individuals living within 1 mile of a golf course had more than double the odds of developing Parkinson’s compared to those living over 6 miles away (adjusted odds ratio [aOR] 2.26; 95% CI, 1.09–4.70).
Researchers, led by Mayo Clinic neurologist and epidemiologist Dr Rodolfo Savica, also found that risk was elevated for people in water service areas that included a golf course and relied on shared groundwater, with nearly double the odds of Parkinson’s (aOR 1.96) compared to those in areas without a golf course
Even after adjusting for groundwater vulnerability, people living within one to two miles of a golf course remained at increased risk – suggesting airborne exposure may be a contributing factor, particularly in urban areas, the authors say.
“Public health policies to reduce the risk of groundwater contamination and airborne exposure from pesticides on golf courses may help reduce risk of PD in nearby neighbourhoods”.
According to investigators, the study builds on previous evidence linking Parkinson’s disease to long-term exposure to specific pesticides, including organophosphates, chlorpyrifos, 2,4-D and paraquat – all commonly used in turf management on US golf courses.
“Pesticides such as paraquat and rotenone have been shown to induce Parkinson-like neurodegeneration… through mechanisms involving oxidative stress, mitochondrial dysfunction, and dopaminergic neuron apoptosis,” the authors note.
The findings have landed at a time of intensifying scrutiny over paraquat use in Australia. Although banned in more than 70 countries, including the UK and EU, the herbicide remains legal here and continues to be used in agriculture and some commercial turf applications.
It remains the active ingredient in 141 registered products, sold under brand names such as Gramoxone and Sprayseed. While classified as a Schedule 7 poison, it is still widely available to licensed users.
The Australian Pesticides and Veterinary Medicines Authority (APVMA) is currently reviewing it’s use following growing calls among health professionals to ban the product.
Australian neurologists and Parkinson’s advocates have warned about paraquat’s neurotoxicity for years. Among them is Professor Carolyn Sue, Kinghorn Chair of Neurodegeneration at Neuroscience Research Australia (NeuRA) and Director of Neurosciences at Prince of Wales Hospital (POWH) who welcomed the APVMA’s current review into the chemical’s safety.
“It’s been known in the Parkinson’s disease field for a long time about the risks,” she told InSight+ last year [link here]. “I’m so grateful the review is now underway.”
In its submission [link here] to APVMA, Parkinson’s Australia urged the regulator to apply the precautionary principle, stating: “Given the substantial growing evidence linking paraquat to Parkinson’s disease and the high toxicity, the precautionary principle should be applied. The precautionary principle advocates for preventive action in the face of uncertainty, and the APVMA should be prioritising public health over chemical use” .
The authors of the US study acknowledged several limitations in their design, including the requirement for Parkinson’s cases to reside in Olmsted County at the time of diagnosis, which may have introduced selection bias – though sensitivity analyses using local controls showed consistent results. The study lacked data on occupational history and other known Parkinson’s risk factors such as head trauma and genetic predisposition, raising the possibility of exposure misclassification, they added.