Finn's Take· TL;DRA chemical that has quietly infiltrated American groundwater for over a century may be fueling the explosive rise in Parkinson's disease cases worldwide. Trichloroethylene (TCE), found in industrial solvents, commercial dry cleaners, and household products like cleaning wipes and paint removers, is associated with a 500% increased risk of Parkinson's disease .
For the past 100 years, TCE has been used to decaffeinate coffee, degrease metal, and dry clean clothes . It contaminates the Marine Corps base Camp Lejeune, 15 toxic Superfund sites in Silicon Valley, and up to one-third of groundwater in the U.S. What makes this chemical particularly insidious is its ability to remain invisible while causing devastating health effects.
The number of people with Parkinson's disease has more than doubled in the past 30 years and, absent change, will double again by 2040 . While genetic factors explain some cases, the vast majority of individuals with Parkinson's disease do not have a family history of the disease or carry an identifiable genetic risk factor .
The connection between TCE and Parkinson's was first hinted at in case studies more than 50 years ago . Since then, researchers have documented multiple cases linking occupational exposure to the development of Parkinson's disease. In 2008, researchers reported that among 30 factory workers, three developed Parkinson's after using TCE for many years to degrease and clean metal parts, with these three workers stationed closest to an open TCE vat .
Research in mice and rats has shown that TCE readily enters the brain and body tissue and at high doses damages the energy-producing parts of cells known as mitochondria. In animal studies, TCE causes selective loss of dopamine-producing nerve cells, a hallmark of Parkinson's disease in humans .
The evidence extends beyond laboratory studies. From the 1950s to the 1980s, a million Marines, their families, and civilians at Camp Lejeune were exposed to drinking water levels of TCE that were up to 280 times above what are considered safe levels . Service members at this base have a 70% increased risk of developing Parkinson's disease .
The scope of potential exposure is staggering. The volatile TCE can readily evaporate and enter people's homes, schools, and workplaces, often undetected. This vapor intrusion is likely exposing millions who live, learn, and work near former dry cleaning, military, and industrial sites to toxic indoor air .
Since contaminated underground plumes can travel over a mile, individuals who live far from a contaminated site are still at risk. One plume on Long Island, which was associated with an aerospace company, is over four miles long and two miles wide and has contaminated the drinking water of thousands .
Dozens of professions—including mechanics, sewage workers, and painters—are also at high risk for TCE exposure . Today millions of homes are tested for radon, but few are for the cancer-causing TCE .
Only two states, Minnesota and New York, have banned TCE, but the federal government has not, despite findings by the EPA as recently as 2022 that the chemicals pose "an unreasonable risk to human health" . In January, the Environmental Protection Agency determined that TCE "presents an unreasonable risk of injury to human health," but the agency has not limited the sale or use of the chemical .
Scientists are calling for immediate action on multiple fronts. The research calls for cleanup and containment of sites contaminated with TCE, and a ban on the use of the chemical . Despite the established risks, global TCE use is projected to increase by 3% annually .
The implications extend far beyond individual health concerns. If TCE is proven to cause Parkinson's disease, actions could be taken to cut exposure and "prevent millions of people from ever developing this debilitating and deadly disease" . As researchers continue to investigate this connection, the urgency for regulatory action and public awareness grows, particularly given the chemical's persistent presence in our environment and its potential role in one of the world's fastest-growing neurological conditions.