Resume: Trichlorethylene (TCE), a common chemical used in decaffeinated coffee, metal degreasers and dry-cleaning formulas, has been linked to a 500% increased risk of Parkinson’s disease.
Source: University of Rochester
A common and widely used chemical may be fueling the rise of the world’s fastest growing brain disorder – Parkinson’s disease.
Trichlorethylene (TCE) has been used for 100 years to decaffeinate coffee, degrease metal and dry clean clothes. It contaminates Marine Corps base Camp Lejeune, 15 toxic Superfund sites in Silicon Valley and up to a third of US groundwater.
TCE causes cancer, is associated with miscarriages and congenital heart disease, and is associated with a 500% increased risk of Parkinson’s disease.
In a hypothesis paper in the Journal of Parkinson’s diseaseAn international team of researchers, including University of Rochester Medical Center (URMC) neurologists Ray Dorsey, MD, Ruth Schneider, MD, and Karl Kieburtz, MD, suggest that TCE may be an invisible cause of Parkinson’s.
In the paper, they describe the widespread use of the chemical, evidence linking the toxic compound to Parkinson’s disease, and describe seven individuals ranging from a former NBA basketball player to a Navy captain to a deceased US Senator, who developed Parkinson’s disease or after probably having worked. with the chemical or be exposed to it in the environment.
A ubiquitous and widespread industrial pollutant
TCE was a common solvent used in a number of industrial, consumer, military, and medical applications, including removing paint, correcting writing errors, cleaning engines, and anesthetizing patients. Its use in the US peaked in the 1970s, when more than 600 million pounds of the chemical — or two pounds per American — were produced annually.
About 10 million Americans worked with the chemical or other similar industrial solvents. Although domestic use has since declined, TCE is still used in the US for metal degreasing and dry cleaning
TCE infects numerous locations across the country. Half of the Environmental Protection Agency’s most toxic Superfund sites contain TCE. Fifteen locations in California’s Silicon Valley where the chemicals were used to clean electronics and computer chips. TCE can be found at numerous military bases, including Camp Lejeune in North Carolina.
From the 1950s to the 1980s, one million Marines, their families and civilians working or living on the base were exposed to drinking water levels of TCE and perchlorethylene (PCE), a close chemical cousin, that were up to 280 times higher than what has been considered as safe levels.
TCE and Parkinson’s disease
The link between TCE and Parkinson’s was first suggested in case studies more than 50 years ago. In the intervening years, research in mice and rats has shown that TCE readily enters brain and body tissue and, at high doses, damages the energy-producing parts of cells known as mitochondria. In animal studies, TCE causes selective loss of dopamine-producing nerve cells, a hallmark of Parkinson’s disease in humans.
Individuals who have worked directly with TCE have an increased risk of developing Parkinson’s. However, the authors warn that “millions of others encounter the chemical unknowingly through outdoor air, contaminated groundwater, and indoor air pollution.”
The chemical can contaminate soil and groundwater, leading to underground rivers, or plumes, that can stretch for long distances and migrate over time. One such plume associated with an aerospace company on Long Island, New York, is more than four miles long and two miles wide and has polluted the drinking water of thousands. Others can be found anywhere from Shanghai, China to Newport Beach, California.
Aside from their risks to water, the volatile TCE can easily evaporate and enter people’s homes, schools and workplaces, often unnoticed. Today, this vapor intrusion likely exposes millions of people living, learning and working near former dry cleaning, military and industrial sites to toxic indoor air.
Fumes intrusion was first reported in the 1980s, when radon was found to evaporate from the soil and enter homes and increase the risk of lung cancer. Today, millions of homes are tested for radon, but few for the cancer-causing TCE.
Decades before symptoms appear
The piece profiles seven individuals in whom TCE may have contributed to their Parkinson’s disease. While the evidence linking TCE exposure to Parkinson’s disease in these individuals is circumstantial, their stories highlight the challenges of building the case against the chemical. In these cases, decades have often elapsed between exposure to TCE and the onset of Parkinson’s symptoms.
The case studies include professional basketball player Brian Grant, who played 12 years in the NBA and was diagnosed with Parkinson’s at age 36. Grant was likely exposed to TCE when he was three years old and his father, then a Marine, was stationed at Camp Lejeune. Grant created a foundation to inspire and support people with the disease.
Amy Lindberg was similarly exposed to the contaminated drinking water at Camp Lejeune when she served as a young Navy captain and would be diagnosed with Parkinson’s disease 30 years later.
The piece describes others whose exposure resulted from living near a contaminated site or working with the chemical, including the late U.S. Senator Johnny Isakson, who resigned from office after being diagnosed with Parkinson’s in 2015. Fifty years earlier he served in the Georgia Air National Guard, which used TCE to degrease airplanes.
Addressing the threat to public health
The authors note that “TCE has been threatening workers for more than a century, polluting the air we breathe – both indoors and out – and polluting the water we drink. Global usage is increasing, not decreasing.”
The authors prescribe a series of actions to address the public health threat posed by TCE. They note that contaminated sites can be successfully remediated and indoor air exposure reduced by vapor remediation systems similar to those for radon. There are thousands of contaminated sites in the US alone and this process of cleanup and containment needs to be accelerated.
They call for more research to better understand how TCE contributes to Parkinson’s disease and other diseases. TCE levels in groundwater, drinking water, soil and outdoor and indoor air require closer monitoring and this information should be shared with those who live and work near contaminated sites.
In addition, the authors call for finally an end to the use of these chemicals in the US. PCE is still widely used today in dry cleaning and TCE in vapor degreasing. Two states, Minnesota and New York, have banned TCE, but the federal government has not, despite findings by the EPA in 2022 that the chemicals pose “an unreasonable risk to human health.”
About this Parkinson’s disease research news
Author: Press Office
Source: University of Rochester
Contact: Press Service – University of Rochester
Image: The image is in the public domain
Original research: Open access.
“Trichlorethylene: An Invisible Cause of Parkinson’s Disease?” by Ray Dorsey et al. Journal of Parkinson’s disease
Trichlorethylene: an invisible cause of Parkinson’s disease?
The etiologies of Parkinson’s disease (PD) remain unclear. Some, such as certain genetic mutations and head trauma, are common knowledge or easy to spot. However, these causes or risk factors are not responsible for most cases. There must be other less visible factors at play.
Among these is a widely used industrial solvent and common environmental contaminant that is little recognized for its likely role in PD: trichlorethylene (TCE). TCE is a simple six-atom molecule that can decaffeine coffee, degrease metal parts and dry clean clothes.
The colorless chemical was first associated with parkinsonism in 1969. Since then, four case studies involving eight individuals have associated occupational exposure to TCE with PD.
In addition, a small epidemiological study found that occupational or hobby exposure to the solvent was associated with a 500% increased risk of developing PD. In multiple animal studies, the chemical reproduces the pathological features of PD.
Exposure is not limited to those who work with the chemical. TCE pollutes the outdoor air, affects the groundwater and pollutes the indoor air. The molecule, like radon, evaporates from underlying soil and groundwater and often enters homes, workplaces or schools unnoticed.
Despite widespread contamination and increasing industrial, commercial and military use, clinical studies of TCE and PD are limited.
Here, through a literature review and seven illustrative cases, we argue that this ubiquitous chemical contributes to the global emergence of PD and that TCE is one of the invisible and highly preventable causes. Further research is now needed to investigate this hypothesis.