in Jacksonville, N.C.
In one of the best-documented, large-scale contaminations in U.S. history, the drinking water at the Marine Corps base was contaminated with TCE and other volatile organic compounds from about 1953 to 1987.
The new study of more than 340,000 service members found the risk of PD was 70% higher in Marines stationed at Camp Lejeune in North Carolina during the years 1975-1985, compared with Marines stationed at Camp Pendleton in Oceanside, Calif.
“This is by far the largest study to look at the association of TCE and PD and the evidence is pretty strong,” lead investigator Samuel M. Goldman, MD, MPH, with University of California, San Francisco, said in an interview.
The link is supported by animal models that show that TCE can induce a neurodegenerative syndrome that is “very similar pathologically to what we see in PD,” Dr. Goldman said.
The study was published online in JAMA Neurology.
‘Hundreds of thousands’ at risk
At Camp Lejeune during the years 1975-1985, the period of maximal contamination, the estimated monthly median TCE level was more than 70-fold the Environmental Protection Agency maximum contaminant level. Maximum contaminant levels were also exceeded for perchloroethylene (PCE) and vinyl chloride.
Dr. Goldman and colleagues had health data on 158,122 veterans – 84,824 from Camp Lejeune and 73,298 from Camp Pendleton – who served for at least 3 months between 1975 and 1985, with follow up from Jan. 1, 1997, to Feb. 17, 2021.
Demographic characteristics were similar between the two groups; most were White men with an average age of 59 years.
A total of 430 veterans had PD: 279 from Camp Lejeune (prevalence, 0.33%) and 151 from Camp Pendleton (prevalence, 0.21%).
In multivariable models, Camp Lejeune veterans had a 70% higher risk for PD (odds ratio, 1.70; 95% confidence interval, 1.39-2.07; P < .001).
“Remarkably,” the researchers noted, among veterans without PD, residence at Camp Lejeune was also associated with a significantly higher risk of having several well-established prodromal features of PD, including tremor, suggesting they may be in a prediagnostic phase of evolving PD pathology.
Importantly, they added, in addition to the exposed service members, “hundreds of thousands of family members and civilian workers exposed to contaminated water at Camp Lejeune may also be at increased risk of PD, cancers, and other health consequences. Continued prospective follow-up of this population is essential.”
‘An unreasonable risk’
The new study supports a prior, and much smaller, study by Dr. Goldman and colleagues showing TCE exposure was associated with a sixfold increased risk for PD.
TCE is a ubiquitous environmental contaminant. The EPA Toxics Release Inventory estimates 2.05 million pounds of TCE was released into the environment from industrial sites in 2017.
In an accompanying editorial, E. Ray Dorsey, MD, with the University of Rochester (N.Y.) and coauthors noted the work of Dr. Goldman and colleagues “increases the certainty” that environmental exposure to TCE and the similar compound PCE “contribute importantly to the cause of the world’s fastest-growing brain disease.”
In December, the EPA found that PCE posed “an unreasonable risk” to human health, and 1 month later, it reached the same conclusion for TCE.
“These actions could lay the foundation for increased regulation and possibly a ban of these two chemicals that have contributed to immeasurable death and disability for generations,” Dr. Dorsey and colleagues noted.
“A U.S. ban would be a step forward but would not address the tens of thousands of TCE/PCE-contaminated sites in the U.S. and around the world or the rising global use of the toxic solvents,” they added.
This research was supported by Department of Veterans Affairs. Dr. Goldman reported no relevant financial relationships. Dr. Dorsey has received personal fees from organizations including the American Neurological Association, Elsevier, International Parkinson and Movement Disorder Society, Massachusetts Medical Society, Michael J. Fox Foundation, National Institutes of Health, and WebMD, as well as numerous pharmaceutical companies.
A version of this article originally appeared on Medscape.com.