Scientists Thought Parkinson’s Was in Our Genes. It Might Be in the Water

Lead

In recent years researchers have shifted from genetics toward the environment to explain rising Parkinson’s rates. Veterans who lived at Marine Corps Base Camp Lejeune and other exposed populations now link trichloroethylene (TCE) — a long‑used industrial solvent — to increased Parkinson’s risk and faster progression. New epidemiology and lab experiments, including mouse inhalation studies, strengthen the case that TCE is neurotoxic and may have contributed to clusters of disease. If confirmed, the finding would reframe prevention and regulation as primary tools against a growing Parkinson’s burden.

Key Takeaways

• Parkinson’s is the second most common neurological disease in the U.S.; roughly 90,000 Americans are diagnosed each year.
• Genetics explains only about 10–15% of Parkinson’s cases; the majority remain unexplained by DNA alone.
• Historical contamination at Camp Lejeune included TCE in groundwater for decades; Marines and families drank and vapor‑exposed it in homes on base.
• An epidemiological study comparing Lejeune and Camp Pendleton veterans found Lejeune exposure was associated with a roughly 70% higher risk of Parkinson’s.
• Laboratory inhalation studies in mice exposed to TCE show loss of dopamine neurons in the substantia nigra and measurable motor and cognitive changes.
• Other chemicals—MPTP and the pesticide paraquat—have previously established chemical links to Parkinson’s, reinforcing TCE as a plausible neurotoxin.
• Regulatory action accelerated in late 2024 when the U.S. Environmental Protection Agency moved to ban TCE; the policy environment remains contested.

Background

For decades Parkinson’s research privileged genetics. High‑profile donors and genomic advances concentrated funding on genes such as LRRK2 and familial clusters discovered in the 1990s, and the Human Genome Project shifted scientific attention and philanthropic dollars to sequencing and gene discovery. That focus produced important discoveries — including genetic variants that raise risk — but left environmental hypotheses underfunded for a generation.

At the same time, epidemiologists and toxicologists documented chemical causes of parkinsonism. A landmark 1980s cluster of acute, MPTP‑induced parkinsonism in drug users established that a synthetic compound can selectively kill dopamine neurons. Subsequent work connected pesticides such as paraquat to increased Parkinson’s incidence in agricultural workers, suggesting chemicals can mimic or accelerate disease pathways once assumed to be primarily genetic.

Camp Lejeune, a large Marine Corps complex in North Carolina, experienced decades of solvent contamination. TCE—widely used across mid‑century American industry for degreasing and dry cleaning—entered groundwater and persisted. For many residents the exposure was invisible: contaminants vaporized into homes and entered indoor air during routine water use, making identification and retrospective exposure measurement difficult.

Main Event

Amy Lindberg, a Navy officer who lived and worked at Camp Lejeune, developed Parkinson’s in her late 50s after years of service and retirement near the North Carolina coast. Her case is one of many prompting fresh scrutiny of Lejeune’s water history. Veterans and their families have reported excess cancers, birth defects and other illnesses dating back decades, and local epidemiology documented elevated risks for several cancers among those stationed there.

In 2017 epidemiologist Sam Goldman used VA records and service histories to compare Parkinson’s diagnoses among Marines who lived at Lejeune with those stationed at Camp Pendleton, a West Coast base with uncontaminated drinking water. His analysis found a 70% higher likelihood of Parkinson’s among Lejeune veterans. A later follow‑up linked higher TCE exposure with faster disease progression.

Toxicologist Briana De Miranda recreated long‑term inhalational exposure to low levels of TCE in mice, modeling the kind of vapor exposures residents likely experienced. Her lab reports loss of dopamine neurons in the substantia nigra, subtle gait and motor defects, and early cognitive changes in exposed animals—findings that echo the neuropathology observed in human Parkinson’s and the MPTP experiments of the 1980s.

The convergence of epidemiology and animal toxicology has renewed attention to TCE as a plausible environmental driver of Parkinson’s. These results helped catalyze regulatory action: in December 2024 the Environmental Protection Agency moved to restrict or ban TCE for many uses, citing emerging evidence of harm to human health and the nervous system.

Analysis & Implications

If TCE is a substantial contributor to Parkinson’s, the public‑health implications are large. Parkinson’s cases in the U.S. have roughly doubled over the past 30 years and are projected to grow further; shifting even a portion of that burden from preventable exposures to regulation and remediation could reduce future incidence. Prevention would require identifying contaminated sites, improving water systems, and curbing ongoing uses of neurotoxic solvents.

From a research perspective, these findings illustrate a broader paradigm shift: chronic diseases often emerge from gene–environment interactions rather than singular genetic causes. While genomics revealed risk architectures and causal pathways, exposomics — the comprehensive mapping of lifetime environmental exposures — promises complementary insight. If scaled, exposome studies could prioritize chemicals for regulation and identify high‑risk exposure windows for intervention.

Economically and politically, the stakes are high. Remediating contaminated sites and restricting chemicals carries cost and industry resistance; yet the costs of untreated chronic disease—medical care, lost productivity, disability—are large and rising. Policy debates over TCE and similar chemicals therefore pit short‑term business interests against long‑term public‑health and fiscal concerns.

Clinically, the research reinforces prevention and symptom management. For exposed individuals, faster diagnosis, targeted monitoring, and therapeutic strategies (including exercise, which has been shown to improve dopaminergic function) can mitigate progression. For populations, the TCE work argues for systematic exposure surveillance and stronger environmental regulation as public‑health tools.

Comparison & Data

The numerical increases above come from published and reported analyses comparing health outcomes among populations exposed to Lejeune’s contaminated water with unexposed cohorts. Such comparisons strengthen causal inference when combined with toxicology that reproduces neuropathology, though absolute risk for an individual depends on exposure dose, duration, age, and genetic susceptibility.

Reactions & Quotes

Researchers and advocates responded swiftly as evidence accumulated and regulatory steps followed.

I think TCE is the most important cause of Parkinson’s in the US.

Ray Dorsey, University of Rochester (neurologist)

Context: Dorsey, a leading Parkinson’s researcher and co‑author of Ending Parkinson’s Disease, positions chemical exposure as a primary driver of the rising case counts and says regulatory removal of key toxicants could substantially reduce incidence.

The discovery [of MPTP] promised to turn the entire field of Parkinson’s disease upside down.

William Langston (neurologist)

Context: Langston’s 1980s work linking MPTP to acute parkinsonism reframed the field by demonstrating how a chemical can selectively destroy dopamine neurons, providing a biological precedent for contemporary TCE concerns.

More than two‑thirds of people with PD don’t have any clear genetic link.

Briana De Miranda (University of Alabama at Birmingham, researcher)

Context: De Miranda emphasizes the gap genetics leaves and the research imperative to identify environmental contributors through both epidemiology and mechanistic toxicology.

Unconfirmed

• Whether TCE exposure alone explains all excess Parkinson’s cases at Camp Lejeune; current evidence supports a strong association but causation at the population level requires additional longitudinal and mechanistic confirmation.
• The article’s report that a federal administration moved to reverse the EPA ban shortly after a December 2024 action is inconsistent with standard timelines and requires checking of policy records and official statements.
• Individual susceptibility factors—precise genetic variants, co‑exposures, and timing of exposure—that determine why some similarly exposed people develop Parkinson’s and others do not remain incompletely defined.

Bottom Line

Emerging epidemiology and experimental toxicology combine to make TCE a credible environmental risk factor for Parkinson’s disease. The evidence does not yet declare single‑cause certainty for every case, but it raises prevention as a logical public‑health priority: reduce exposures, remediate contaminated sites, and limit use of neurotoxic solvents.

The broader lesson is methodological as much as scientific. Genomics clarified biological susceptibility, but exposomics and classical epidemiology are necessary complements to identify preventable environmental drivers of chronic disease. Policymakers, clinicians, and funders must balance investments in genetic research with long‑term surveillance and rigorous chemical testing to reduce future disease burdens.

Sources

• WIRED — feature on Camp Lejeune, TCE, and Parkinson’s (journalism)
• Centers for Disease Control and Prevention — Parkinson’s disease information (federal public health agency)
• U.S. Environmental Protection Agency — chemical regulatory actions and notices (federal regulator)
• University of Rochester — Ray Dorsey profile and research (academic)