People who live within about 500 feet of a dry cleaner had a 14 percent higher risk of developing Parkinson's disease than those living several miles away, according to a nationwide analysis published this month in the journal npj Parkinson's Disease. The closer people lived to a dry cleaner, the greater the risk.
The research was led by scientists at the Barrow Neurological Institute in Phoenix. It compared 180,982 Medicare beneficiaries aged 67 and older who received a new Parkinson's diagnosis between 2016 and 2018 with more than 18.8 million controls without the disease.
Because the design is observational, it cannot prove that dry cleaners cause Parkinson's disease. The pattern was consistent across the country, however, and it held up after the researchers adjusted for age, sex, race, smoking, healthcare use, air pollution, and neighborhood income.
Which chemicals are the concern
The researchers point to two chlorinated solvents long tied to the industry. The first is trichloroethylene, better known as TCE. The second is perchloroethylene, or PCE, which is still widely used in dry cleaning and can break down into TCE in soil and groundwater.
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Both chemicals can persist for years around contaminated sites, even after a facility has closed. Previous research has linked long-term TCE exposure to the loss of dopamine-producing brain cells, the hallmark of Parkinson's disease.
The U.S. Environmental Protection Agency banned most uses of TCE in December 2024, following decades of evidence tying it to Parkinson's and other serious health problems. But contamination around older commercial sites is expected to linger for years.
A dose-response pattern
The link was strongest for the gait and balance form of Parkinson's disease. Older adults living within roughly 500 feet of a dry cleaner had about 23 percent higher odds of that subtype, according to the analysis summarized by Parkinson's News Today.
Geographic hotspots included southeastern Illinois, the Tennessee-Kentucky border, and the Dallas area. Researchers described the overall pattern as a clear dose-response relationship, meaning the risk rose steadily as distance to the nearest dry cleaner fell.
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"This study adds to growing evidence that environmental exposures may play an important role in Parkinson's disease. Identifying those exposures is an important step toward understanding how we might reduce the burden of this disease in the future," said Brad Racette, MD, chair of neurology at Barrow Neurological Institute and the study's senior author.
What it means for the average household
The findings do not point to a specific action homeowners need to take today, and the study did not measure actual TCE or PCE levels in the air, soil, or water around participants' homes. Distance was used as a stand-in for exposure.
Roughly 90,000 Americans are diagnosed with Parkinson's disease each year, and an estimated 1.2 million people in the country will be living with the condition by 2030, according to the Parkinson's Foundation. Age is by far the strongest known risk factor.
Environmental exposure is only one piece of the puzzle. Other work has suggested links between Parkinson's disease and factors ranging from pesticides to chronic traffic noise. Anyone concerned about tremor, stiffness, or changes in walking should speak with a doctor, since early signs of Parkinson's disease can appear years before a formal diagnosis.
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This article is made and published by Jesper Bengtson, who may have used AI in the preparation.