Common chemicals linked to Parkinson’s disease

March 21, 2023 – Amy Lindberg, a 63-year-old retired Navy captain, began experiencing troubling symptoms 6 years ago.

“I had anxiety, depression and cognitive issues — ‘brain fog’ — and they didn’t go with me,” she said. “I have a thyroid problem and went through menopause, but these didn’t seem like my usual thyroid or menopausal problems.”

Lindberg consulted a neuropsychologist and was diagnosed with mild cognitive impairment and major depressive disorder.

“But while he was assessing me, he asked questions that I thought were strange for a psychologist. He wanted to know if I had a problem with my sense of smell. He wanted to see my arm swing.

Lindberg, who also had rest tremors in his right hand, did have problems with smell and very limited arm swing. The psychologist referred him to a neurologist, who diagnosed him with Parkinson’s disease.

Lindberg’s disease likely has its roots in a 4-year period of exposure to trichlorethylene (TCE), a common chemical found in gun cleaners, cleaning products, and many other commercial products. According to to a new page according to an international team of scientists, TCE is associated with an increased risk of Parkinson’s disease by up to 500%.

When Lindberg was in his 20s, he was stationed at Camp Lejeune, a Marine Corps base in North Carolina. “I was there from 1984 to 1988 and without knowing it, I was drinking, cooking and swimming in polluted water.” It has since become known that the water at Camp Lejeune was contaminated with TCE.

Lindberg is one of seven people whose stories are told in the researchers’ study, which includes a thorough review of animal and human studies up to the present day. Overall, the data suggest a disturbing relationship between TCE exposure and the development of Parkinson’s disease, often decades later.

Unknown exposure

TCE was created in a laboratory in 1864, and commercial production began in 1920, the authors wrote.

“Because of its unique properties, TCE has had countless industrial, commercial, military and medical applications, including refrigeration, electronic cleaning and degreasing of engine parts. It was even used to decaffeinate coffee until the 1970s. Historically, it was used in dry cleaning, although today a similar chemical, perchlorethylene (PCE), is used instead.

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TCE use peaked in the 1970s, when it was, in the words of the authors, “ubiquitous.” About 10 million Americans worked with it or similar chemicals. Although these numbers are lower today, a significant number of Americans are still exposed to this toxic chemical on a daily basis.

TCE exposure is not limited to those who work with it, as it pollutes outdoor air, pollutes ground water, and pollutes indoor air. It contaminates up to a third of US drinking water and is found in half of the 1,300 most toxic Superfund sites in the federal cleanup program, including 15 sites in California’s Silicon Valley where TCE has been used to clean electronics.

Although the military has stopped using TCE, the chemical has been found on many military bases, including Camp Lejeune. From the 1950s to the 1980s, 1 million Marines, their families, and civilians who worked or lived on the base had drinking water levels of TCE and PCE 280 times higher than levels considered safe.

“Exposure can be occupational or environmental and is often largely unknown at the time of occurrence,” lead author Ray Dorsey, MD, a professor of neurology at the University of Rochester in New York, said in an interview. .

“Fastest growing brain disease”

Dorsey calls Parkinson’s “the fastest growing brain disease in the world.” He said that genetic factors alone (which affect only about 15% of people with Parkinson’s) cannot explain the rapid increase in new diagnoses, nor can it be explained by aging.

“Certain pesticides … are likely causes, but they do not explain the high prevalence of PD in urban areas like the United States,” he said. Rather, other factors are involved, and “TCE is probably one of those factors,” Dorsey said. But despite the widespread contamination and frequency of use of the chemical, there have been few studies of the link between TCE and Parkinson’s disease, he said.

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To fill this gap, Dorsey and his colleagues took a deep dive into studies focusing on a possible link between TCE and Parkinson’s disease and presented seven cases to demonstrate the connection.

They reviewed studies dating back 50 years, when the link between TCE and Parkinson’s disease was first suggested. Since then, research in mice and rats has shown that TCE readily enters the brain and body tissues at high doses.

One of them the authors examined human studies compared the risk of Parkinson’s disease in twins where one twin was exposed to TCE and the other was not. Researchers found that the risk of Parkinson’s disease increased by 500% in those exposed to it.

“TCE damages the energy-producing parts of cells, the mitochondria,” Dorsey said. Neurons that produce dopamine, a brain chemical that is lower in people with Parkinson’s disease, are particularly sensitive to TCE’s toxins. “This may partly explain the link.”

Public health opportunities

All seven people whose stories were told grew up in, or spent time in, regions where they were exposed to TCE, PCE, or similar chemicals, or were exposed through their work.

The authors acknowledge that the role of TCE in Parkinson’s disease is “far from definitive.” Exposure to TCE is often combined with exposure to other toxins or unmeasured genetic risk factors.

But they note that Parkinson’s disease isn’t the only health problem linked to TCE. The chemical has been linked to miscarriage, many forms of cancer, neural tube defects and many other conditions.

“Countless people have died over generations from cancer and other TCE-related illnesses, [and] Parkinson’s may be the latest,” Dorsey said. “Banning these chemicals, containing the materials in contaminated sites, and protecting homes, schools, and buildings at risk could create a world where Parkinson’s disease is increasingly rare, not uncommon.”

For example, indoor air exposure can be improved by dehumidification. And while efforts are underway to clean up and contain contaminated sites, those efforts must be accelerated. The authors also recommend that more research be done to understand how TCE contributes to each disease.

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Advocacy efforts

Brian Grant is one of those featured in the paper. A once successful NBA player who spent 12 years in the league, Grant developed symptoms of Parkinson’s disease at the age of 34 and retired from basketball. 2 years later he was officially diagnosed.

Grant is glad that researchers are shining a spotlight on the role of TCE and similar chemicals in Parkinson’s disease because he was exposed to it when he was 3 years old when his father, then a Marine, was stationed at Camp Lejeune. His father later died of esophageal cancer, a disease known to be linked to TCE.

“I know firsthand how difficult it is to live with PD,” Grant said. “I’ve seen the burden it puts on families and communities.” And Grant fears that his children and grandchildren may also catch the disease.

“So as I learned from Dr. Dorsey about the research linking chemicals like TCE to PD, I feel it’s important because we can do something about it. There are things we can do to prevent future generations from getting the disease,” Grant said.

He created a foundation to “enable people affected by PD to live active and fulfilling lives”.

Lindberg also volunteers to help veterans apply for disability and health benefits provided by the Veterans Administration to those stationed at Camp Lejeune from 1953 to 1987. Parkinson’s disease is considered a “presumptive condition” that qualifies for these benefits based on the disability rating scale. .

She also worries about the effects of contaminated water on her children, especially since she was pregnant during her years at Camp Lejeune. Like Grant, she strives to make the world a better place for people with Parkinson’s.

“I’m an advocate for it at the local, state and national level,” she said. “I want to improve the quality of life for people with PD and stop how quickly this disease progresses.”