Symptoms take decades to develop, UCSF-SFVA-led study shows

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Previous research has linked TCE, or trichlorethylene, to certain types of cancer, but a new study published in JAMA Neurology on May 15, 2023, it is believed to be the first large-scale study to demonstrate its association with Parkinson’s.

TCE has been used industrially and commercially for nearly 100 years and was used as a surgical anesthetic until it was banned in 1977. More recently, it was used as a degreasing solvent. Today, it is mainly used to degrease industrial metal parts. This involves heating TCE in degreaser tanks to create a vapor that dissolves the grease, but also releases the chemical into the atmosphere. Once TCE enters soil or groundwater, it can persist for decades.

In the study, researchers led by UC San Francisco and the San Francisco VA Medical Center compared Parkinson’s diagnoses in approximately 160,000 Army and Marine veterans. A little more than half came from Camp Lejeune in North Carolina, where TCE was used to degrease military equipment and the water was contaminated; the rest came from Camp Pendleton in California, where the water was not contaminated.

Service members spent at least three months in the camps between 1975 and 1985, a period in which TCE in the water at Camp Lejeune exceeded maximum safe levels by 70 times. The researchers had access to follow-up health data on service members between 1997 and 2021, at which time Parkinson’s disease might be expected to develop.

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

The civilian population is also at risk from TCE exposure, said first author Samuel M. Goldman, MD, MPH, of the UCSF/SFVA Division of Occupational, Environmental and Climate Medicine, noting that between 9% and 34% of US water supplies contain measurable amounts of the chemical.

TCE production has increased

“TCE continues to be a very commonly used chemical in the United States and around the world. Its production has increased in recent years and it is widely available online,” he said.

“Unfortunately, there’s no easy way to tell 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’s metabolized and excreted very quickly, so blood and Urine tests only reflect very recent exposure.”

In addition, the researchers found that Lejeune veterans had a higher prevalence of prodromal Parkinson’s, symptoms that suggest Parkinson’s but do not yet meet diagnostic criteria for the disease.

“Loss of the sense of smell, a sleep disorder known as RBD, anxiety, depression and constipation can be early signs of Parkinson’s, but only a very small fraction of people who have it will develop it,” said the author. Principal, Caroline M. Tanner, MD. , PhD, from the UCSF Department of Neurology, the Weill Institute for Neurosciences, and the SFVA.

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