Research Suggests a Link Between Chemical, Parkinson's

Environmental factors must be behind proliferation of disease, expert says
By Bob Cronin,  Newser Staff
Posted Mar 16, 2023 5:25 PM CDT
Researchers Suspect TCE, Parkinson's Connection
A worker drives a metal rod into the ground to collect soil samples at the former Santa Susana Field Laboratory, a contaminated site, in Simi Valley, Calif., in 2013.   (AP Photo/Jae C. Hong)

A widely used, cancer-causing industrial chemical could be one factor in the rapid increase in Parkinson's disease, new research shows. Thousands of US sites are contaminated by trichloroethylene, which has been employed to remove paint, gunk from jet engines, and stains from shirts by dry cleaners, the Los Angeles Times reports. The research, published in the Journal of Parkinson’s Disease, does not conclusively connect TCE and the degenerative brain disease. But the authors call for more research, saying other studies have produced similar findings. And the lead author said environmental factors have to be behind the condition's growth.

In 1817, Dr. James Parkinson reported that six people had the disease, said Ray Dorsey, a neurology professor at the University of Rochester. Now, the global estimate is 6 million, an increase that aging could not account for, he said. "So how do you go from six to 6 million? ... It has to be environmental factors," Dorsey said. "I think TCE and air pollution are important contributors." Exposure has increased because some contaminated sites have been turned into housing developments. Others once were remote but now are approached by development. "When a patient tells me about possible exposure, I Google their location and I almost always find a contaminated site," Dorsey said.

A connection was first suspected in 1969, after a man who worked with TCE for 30 years developed Parkinson's disease symptoms. In 2012, a study of twins found regular exposure associated with about a 500% increase in the likelihood of developing the disease, which brings uncontrollable tremors. The authors of the latest paper suggest close monitoring of contaminated sites and more research, per the Times. Past studies of TCE's effects often have centered on cancer, said Penny Newman, founder of the California's Center for Community Action and Environmental Justice. "And we've always said that there are other ancillary diseases and illnesses that show up with this that they’re not picking up on." (More Parkinson's disease stories.)

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