Living within 500 feet of a dry cleaner could elevate an individual's risk of developing Parkinson's disease by 14%, according to a recent study by researchers in Arizona. The findings suggest a potential environmental factor contributing to the neurodegenerative disorder.
Parkinson's disease, which affects an estimated one million Americans, is characterized by progressive damage to parts of the brain, leading to tremors, movement problems, and a decline in independence. While pollution, pesticides, and smoking have been implicated as contributing factors to its rise, this new research explores the role of chemicals associated with dry cleaning.
The study analyzed the medical records of 18 million Medicare patients across the United States, identifying 180,000 individuals diagnosed with Parkinson's disease. Researchers compared the residential locations of these patients to the locations of approximately 33,000 dry cleaning establishments operating in 2013.
Results indicated that individuals living within 500 feet of a dry cleaner showed a 14% increased risk of Parkinson's compared to those residing four to five miles away. Stronger associations were observed in metropolitan areas such as New York City, southern California, Michigan, and parts of the South, as well as Dallas-Fort Worth, Detroit, southern Illinois, the Tennessee-Kentucky border region, central Pennsylvania, and north-central Indiana.
Researchers hypothesize that chemicals used in dry cleaning processes, such as tetrachloroethylene (TCE) and perchloroethylene (PCE), may leach into the soil. These chemicals can be released as vapors that are inhaled by nearby residents. Once in the body, scientists suggest these chemicals could potentially damage dopamine-releasing neurons in the brain, which are crucial for controlling movement and are targeted in Parkinson's disease.
Further analysis revealed specific associations with subtypes of Parkinson's. Those living within 0.1 miles (approximately 2,000 steps) of a dry cleaner had a 23% higher risk of developing Parkinson's with gait instability, a subtype characterized by walking or balance issues. Additionally, a 25% increased risk was found for Parkinson's disease accompanied by dementia or cognitive decline, and a 19% higher risk for diagnosis following a fall. No significant association was found with tremor-defined Parkinson's, another common form of the disease.
The study's authors cautioned that their findings do not definitively prove causation but suggest a significant association that warrants further investigation. The study noted several limitations, including potential inaccuracies in location data and the assumption that patients had always lived near the dry cleaners. It also acknowledged that some locations might be drop-off points rather than active cleaning facilities, and other environmental factors like general neighborhood pollution could not be entirely discounted.
Parkinson's disease is projected to affect 1.2 million Americans by 2030, with an estimated 90,000 new diagnoses annually. The Parkinson's Foundation notes that only about 15% of cases have a known family history, highlighting the potential role of environmental influences. Previous recommendations for reducing Parkinson's risk have included minimizing exposure to toxic chemicals, such as washing produce thoroughly to remove pesticides and seeking out dry cleaners that do not use chemicals like PCE and TCE.