by James Lyons-Weiler, PhD, Popular Rationalism, ©2025
(Dec. 26, 2025) — Parkinson’s disease (PD) is a chronic, progressive neurodegenerative disorder that affects movement, balance, cognition, and autonomic function. With more than 10 million people affected globally and over 1 million in the United States alone, Parkinson’s has emerged as one of the most urgent public health challenges of the 21st century. According to the Global Burden of Disease (GBD) study, the age-standardized mortality rate associated with PD has more than doubled in the past three decades, and it is now the fastest-growing neurological condition worldwide in terms of prevalence, disability-adjusted life years (DALYs), and death.
Forecasts suggest that the global incidence of PD will double by 2040, driven by aging populations and by increasing environmental exposures linked to disease onset and progression. While 10–15% of PD cases can be attributed to specific genetic variants, the vast majority are considered idiopathic, emerging from complex interactions between genetic vulnerability and environmental insults.
There has been insufficient response by public health agencies on this pandemic.
This article reviews the environmental factors most strongly associated with increased Parkinson’s disease risk, drawing on high-quality epidemiological studies and validated exposure models. It also provides evidence-informed strategies for individuals, clinicians, and policymakers to reduce or eliminate those risks.
Key Environmental Exposures Linked to Parkinson’s Disease
A. Pesticides and Herbicides
Among the most heavily implicated environmental contributors to PD are agricultural and turf-management chemicals, particularly herbicides and fungicides known to affect mitochondrial integrity and dopamine synthesis. The herbicide paraquat has received particular scrutiny due to its capacity to redox cycle and generate reactive oxygen species (ROS), damaging dopaminergic neurons in the substantia nigra. In a 2024 case-control study by Paul et al., continuous occupational or residential proximity to paraquat-treated areas since 1974 was associated with an odds ratio (OR) of 2.15. The same study reported a dose-response relationship with increasing application intensity near workplaces, further strengthening causal inference.
Maneb and ziram, two manganese-containing dithiocarbamate fungicides, have also been associated with increased PD risk, particularly when exposures occur concurrently with paraquat. A landmark study by Costello et al. (2009) in California’s Central Valley demonstrated a more than fourfold increased risk (OR 4.17) for early-onset Parkinson’s among individuals exposed to both maneb and paraquat within 500 meters of their residence between 1974 and 1989. These chemicals impair mitochondrial function and interfere with the synthesis of dopamine, the neurotransmitter whose loss underpins the classical motor symptoms of PD.
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