Rethinking Parkinson’s: From Genetic Destiny to Environmental Threats in Our Water
Parkinson’s disease (PD), the second most common neurodegenerative disorder after Alzheimer’s, affects millions worldwide, with around 90,000 new diagnoses in the US each year. For decades, research heavily emphasized genetics as the primary cause, fueled by high-profile funding and discoveries.
However, rising incidence rates—doubling in the US over the past 30 years and projected to increase further—suggest otherwise. Emerging evidence points to environmental factors, particularly contaminants like trichloroethylene (TCE) in drinking water, as major contributors. If true, this shift could make much of PD preventable.
The Genetic Focus and Its Limitations
PD research has been dominated by genetics, with studies on genetic causes outnumbering environmental ones 6:1. Billions from donors like Sergey Brin and the Michael J. Fox Foundation poured into gene hunting. Yet only 10-15% of cases are purely genetic, and up to 75% remain unexplained. Twin studies show similar PD rates in identical and fraternal pairs, undermining a strong hereditary role. Experts like Ray Dorsey of the University of Rochester argue that environment and lifestyle dwarf genetics in influence—potentially 10 times more impactful on early mortality, per large-scale studies.
Breakthrough: Toxins Can Trigger PD
A pivotal moment came in 1982 with the “frozen addicts.” Young people injecting contaminated synthetic heroin developed severe PD-like symptoms overnight due to MPTP, a byproduct that destroys dopamine-producing neurons in the brain’s substantia nigra. This proved chemicals could cause parkinsonism. Neurologist Bill Langston’s work linked it to pesticides like Paraquat, still used in the US despite bans elsewhere.
Camp Lejeune: A Real-World Case Study
At Marine Corps Base Camp Lejeune, North Carolina, groundwater was heavily contaminated with TCE—a industrial solvent—for decades until the 1980s. Veterans like retired Navy officer Amy Lindberg, diagnosed at 57, suspect this exposure. Studies show Lejeune residents had 70% higher PD risk compared to a similar uncontaminated base. Higher exposure levels accelerated disease progression. TCE, linked to cancers and other issues, contaminates up to 18% of US water sources, affecting millions.
Lab Proof and Broader Implications
Researcher Briana De Miranda exposed mice to TCE inhalation mimicking human levels; results showed dopamine neuron loss, movement impairments, and cognitive decline. The EPA banned TCE in late 2024, though regulatory changes loom. Scientists estimate up to 90% of PD cases could be environmental, interacting with genes (“genetics loads the gun, environment pulls the trigger”).
This extends beyond PD: Rising chronic diseases like autism and cancers highlight under-tested chemicals (only 1% of 350,000 in use). Proposals for a “Human Exposome Project” aim to map lifetime exposures comprehensively.
Steps Toward Prevention
Individuals can reduce risks: filter water, use air purifiers, avoid microwaving plastics, choose organic foods, and skip fragranced products. Exercise, like high-intensity interval training, may slow progression by boosting dopamine.
PD’s story underscores that many modern illnesses stem from preventable exposures, not inevitable fate. Identifying and curbing toxins like TCE and pesticides could dramatically lower cases.
(Adapted from the original article by Matt Reynolds, published in WIRED on December 10, 2025.)
