Dry cleaning an “invisible cause of Parkinson’s”? Researchers urge action on TCE contamination

16 Mar 2023 --- Trichloroethylene (TCE) – a colorless chemical used in aerosol cleaning products, cosmetic glues, disinfectants and perfumes – has been hypothesized as a cause of Parkinson’s disease (PD), by an international team of researchers.

“The number of people with PD has more than doubled in the past 30 years and, absent change, will double again by 2040,” the researchers warn. The brain disorder causes uncontrollable movements and makes it difficult for balancing and coordination.

In the paper published in the Journal of Parkinson’s Disease, the researchers detail the widespread use of the chemical, the evidence linking the toxicant to PD and profile seven individuals – ranging from a former NBA basketball player to a Navy captain to a late US Senator – who developed PD either after likely working with the chemical or being exposed to it.

The authors say that the evidence linking TCE exposure to PD is circumstantial and limited, highlighting a need for future in-depth research. They add that while TCE’s effects on cancer are “well-documented, its effects on PD are only recently coming to light.”

According to the US Centre for Disease Control, TCE is classified as a carcinogen by the Department of Human Health Services, the International Agency for Research on Cancer and the Environmental Protection Agency (EPA).

“Other effects seen in people exposed to high levels of TCE include nervous system effects related to hearing, seeing and balance, changes in the rhythm of the heartbeat, liver damage and evidence of kidney damage. Some people who get concentrated solutions of trichloroethylene on their skin develop rashes,” the CDC states.Possible modes of exposure to trichloroethylene in the environment. (Image credit: E.R. Dorsey et al./Trichloroethylene and Parkinson’s Disease.)

Chemical risk
TCE is classified as a substance of “very high concern” in the EU and has been subject to REACH authorization since 2014. The European Chemicals Agency lists carcinogenic, suspected mutagenic and skin-sensitizing properties of concern for TCE.

The international team of researchers – including University of Rochester, US, Medical Center neurologists Ray Dorsey, Ruth Schneider and Karl Kieburtz – postulate that TCE may be an invisible cause of PD.

The study states that half of the 1,300 “most toxic” EPA Superfund sites – part of a federal clean-up program – contain TCE. Fifteen sites are in California’s Silicon Valley, where the chemicals were used to clean electronics and computer chips.

Additionally, TCE is found in numerous military bases, including Camp Lejeune in North Carolina. From the 1950’s to the 1980’s a million marines, their families and civilians that worked or resided at the base were exposed to drinking water levels of TCE and perchloroethylene – a close chemical cousin – up to 280 times above what is considered safe levels.

The researchers warn that while individuals with direct exposure are at an elevated risk of developing PD, millions more encounter the chemical unknowingly through outdoor air, contaminated groundwater and indoor air pollution.

Call to action
The authors note that “for over a century, TCE has threatened workers, polluted the air we breathe – outside and inside – and contaminated the water we drink. Global use is waxing, not waning.” 

They propose conducting more research, given the widespread environmental contamination by TCE. Additionally, they suggest cleaning and containing contaminated sites.

“Hundreds of thousands of sites are contaminated across the US and globally. They are found in strip malls where dry cleaners used to operate, on military bases where use was widespread, in cities near old manufacturing sites (especially those near rivers or streams) and in rural areas where landfills were created to dump hazardous waste,” the study elaborates.

“Contaminated sites can be remediated, and homes, schools and workplaces can be protected by vapor intrusion mitigation systems like those used for radon. Until they are cleaned, existing contaminated sites must be contained, limiting exposure for humans and nature.”

Moreover, the researchers call for monitoring TCE levels and publicly communicating risks, banning TCE and listening to patient complaints for better care.

Edited by Radhika Sikaria