Living Near a Dry Cleaner May Be Linked to Higher Parkinson's Risk

Most cases of Parkinson’s disease (PD) can’t be explained by genetics alone. Ten to 15% of people with Parkinson’s have a known genetic tie to PD, which means environmental factors — such as the chemicals we’re exposed to in the air, water and soil — likely play a major role in the disease.

One concerning chemical is called trichloroethylene (TCE), an industrial solvent long used in degreasing, manufacturing and dry cleaning. TCE is the most common organic contaminant in groundwater. A growing body of research has linked TCE to Parkinson’s, including studies of factory workers and of military personnel exposed to contaminated drinking water at Camp Lejeune in North Carolina.

A new study published in npj Parkinson’s Disease examines whether there’s a link between living near a dry cleaner — a common source of these solvents — and the risk of Parkinson’s. Researchers at the Barrow Neurological Institute in Phoenix, AZ, analyzed data from nearly 19 million older adults across the U.S. and found that people living closest to a dry cleaner had a modestly higher risk of Parkinson’s.

The study was led by Brittany Krzyzanowski, PhD — the same researcher who examined the link between the pesticides used in golf courses and PD risk — who is a Parkinson’s Foundation research grant recipient. 

Study Results

Dr. Krzyzanowski used Medicare records to compare about 181,000 people newly diagnosed with Parkinson’s between 2016 and 2018 to more than 18 million people without the disease. For each person, they measured the distance from their home to the nearest dry cleaner, then adjusted for factors that could muddy the picture — age, sex, race, smoking, income, air pollution, how urban or rural the area was and how often people used health care.

After accounting for those factors, a pattern emerged: the closer someone lived to a dry cleaner, the higher their risk of Parkinson’s. 

• People living within 500 feet of a dry cleaner were about 14% more likely to be diagnosed with Parkinson’s compared to those living 4 to 5 miles away. 
• The risk rose steadily as distance shrank. This steady pattern — where getting closer means higher risk — shows that there is likely a link, instead of a coincidence.

The researchers also found that the link was not the same for every form of Parkinson’s. The association was strongest in people whose predominant symptoms are gait and balance problems, where living within about a tenth of a mile of a dry cleaner was associated with 23% higher odds. Similar patterns appeared for Parkinson’s associated with dementia and with falls. Notably, there was no association for the tremor-predominant subtype — a finding consistent with other research suggesting environmental toxins tend to drive the balance-and-gait form of the disease rather than the tremor form.

Additionally, the researchers mapped the association across the country (see map below). While the overall pattern held across much of the U.S., there were especially robust associations in certain areas, including the Dallas–Fort Worth area, greater Detroit, southern Illinois, the Tennessee–Kentucky border, central Pennsylvania, north-central Indiana, parts of southern California, and the New York City area extending into New Jersey.

The researchers suggest these regional differences may be due to how easily underground contamination reaches people — which may include factors like aging infrastructure, local geology and population density, though they did not look at this directly.

Study Highlights

• A nationwide study of nearly 19 million older U.S. adults found that living closer to a dry cleaner was associated with a modestly higher risk of Parkinson’s disease.
• People living within 500 feet of a dry cleaner had about 14% higher odds of Parkinson’s compared with those living 4 to 5 miles away, with risk rising steadily the closer they lived to a dry cleaner.
• The link was strongest in people whose primary symptoms are balance problems, falls and dementia, but not for those whose primary symptom was tremor. 
• Certain regions — including parts of Texas, Michigan, Illinois, California and the New York City area — showed especially strong associations.

Overall, the study shows an association between dry cleaners proximity and Parkinson’s. This is not evidence of cause and effect and the study did not directly measure chemical exposure.

Why dry cleaners?

Traditional dry cleaning has relied on chemicals such as TCE and perchloroethylene (PCE). Over time, PCE breaks down time into TCE, which can remain underground for many years. Decades of using these chemicals and improper disposal have left contamination beneath many dry cleaner sites that seep into the ground. These underground chemicals can also become vapors and seep upward into nearby homes and businesses.

"Since this was an observational study, we can't draw causal conclusions. However, the fact that we detected an association within 500 feet of a dry cleaner is concerning, said Dr. Krzyzanowski, study lead. “Historically, exposure from documented contaminated dry cleaners has been complex, with risk depending on factors such as the presence of a groundwater plume, subsurface soil conditions, and groundwater flow direction.”

What does this mean for people with Parkinson's?

The prevalence of Parkinson’s is on the rise, and environmental factors likely play a large role. This study suggests an association between living within close proximity to a dry cleaner and an increased risk of developing PD — providing another accessible, real-world example of the impact that environmental toxins may have in PD. 

Since no measurements of TCE or PCE levels were taken, this is not proof that living near a dry cleaners causes Parkinson’s. Dr. Krzyzanowski emphasizes that more work is needed before drawing firm conclusions. However, studies that tie environmental factors to increased risk are shaping the future of PD research by helping people better understand potential contributors to their diagnosis — and help identify ways to reduce risk for future generations.

Overall, the study adds to a substantial and growing body of evidence linking chlorinated solvents to Parkinson’s — and it points to something potentially actionable in the future. Unlike genetic risk, environmental contamination can, in principle, be cleaned up and prevented. The authors argue their findings support stronger disease monitoring and further environmental investigation of contaminated sites.

“For those who are concerned, especially people living in a building above a dry cleaner, it's worth being aware of the potential for vapor intrusion linked to contamination. One way to get a better understanding is to check whether the dry cleaner appears on the state's list of contaminated dry cleaners or on the federal Superfund list," said Dr. Krzyzanowski.  

Learn More

The Parkinson’s Foundation believes in empowering the Parkinson’s community through education. Learn more about PD and environmental factors through our resources below, or by calling our free Helpline at 1-800-4PD-INFO (1-800-473-4636) for answers to your Parkinson’s questions.

• Environmental Factors
• Camp Lejeune & Increased Risk of Parkinson’s
• Golf Course Pesticides, Drinking Water & Parkinson’s Risk