Exposure to TCE may raise your risk for Parkinson’s, study

Trichloroethylene (TCE) is a liquid chemical that lingers in the air, water, and soil. Millions of people in the US and worldwide are exposed to TCE in air, food, and water.

Occupational exposure to the industrial solvent trichloroethylene (TCE) was previously associated with a 6-fold increased risk of Parkinson’s disease (PD) in a small study of twin pairs discordant for Parkinson’s. Furthermore, despite the fact that TCE and a similar compound are present in up to one-third of US drinking water supplies, only a single underpowered mortality study has assessed the risk of PD from TCE or PCE in drinking water.

A new study by the UC San Francisco and the San Francisco VA Medical Center is the first large-scale study to demonstrate its association with Parkinson’s.

Scientists compared Parkinson’s diagnoses in approximately 160,000 Navy and Marine veterans. The majority came from Camp Pendleton in California, where the water was not contaminated. Still, over half came from Camp Lejeune in North Carolina, where TCE was used to degrease military equipment.

Between 1975 and 1985, service members stayed in the camps for at least three months. During this time, TCE levels in the water at Camp Lejeune were 70 times higher than the maximum safe levels. Between 1997 and 2021—the expected time for Parkinson’s to manifest—the researchers had access to follow-up health information on service members.

Scientists found that 430 veterans had been diagnosed with Parkinson’s, and the Lejeune veterans’ risk was 70% higher than the Pendleton veterans. On average, service members of both camps were stationed there for approximately two years, from 1975 to 1985. Residence began at an average age of 20, and Parkinson’s diagnosis occurred at 54 at Lejeune and 53 at Pendleton, showing that the disease took decades to develop after TCE exposure.

First author Samuel M. Goldman, MD, MPH, of the UCSF Division of Occupational, Environmental, and Climate Medicine, said,“TCE is still a very commonly used chemical in the United States and worldwide. Its production has increased over the past several years and is widely available online.”

“Unfortunately, there’s no easy way to know if you’ve been exposed unless you’ve worked with it directly. Many of us have detectable levels of TCE in our bodies, but it gets metabolized and excreted very quickly, so blood and urine tests only reflect very recent exposure.”

The researchers also discovered that prodromal Parkinson’s, which has symptoms indicative of Parkinson’s but does not yet meet diagnostic criteria, was more prevalent in the Lejeune veterans.

Senior author Caroline M. Tanner, MD, Ph.D., of the UCSF Department of Neurology, the Weill Institute for Neurosciences, and the SFVA said,“Loss of sense of smella sleep disorder known as RBD, anxiety, depression, and constipation can be early signs of Parkinson’s, but only a tiny fraction of people with them will develop it.”

“The risk of developing Parkinson’s in the future can be estimated using a risk score based on these symptoms. The Lejeune veterans had higher risk scores than the Pendleton veterans, suggesting they are more likely to develop Parkinson’s in the future.”

Journal Reference:

1. Samuel M. Goldman, Frances M. Weaver et al. Risk of Parkinson’s Disease Among Service Members at Marine Corps Base Camp Lejeune. JAMA Neurol. DOI: 10.1001/jamaneurol.2023.1168