Is This Environmental Contaminant Linked to Higher Risk of Parkinson’s Disease?

A cancer-causing compound that was used widely for decades to degrease heavy machinery and to remove stains from clothing at dry cleaners could also be linked to Parkinson’s disease, says a new research paper that recommends increased scrutiny and more research on this environmental contaminant.

Trichloroethylene, or TCE, is a colorless, volatile liquid that evaporates quickly into the air. It can be released into water and soil at places where it is produced or used. There is strong evidence that TCE can cause kidney cancer in people, and some evidence for TCE-induced liver cancer and malignant lymphoma, states the U.S. Centers for Disease Control and Prevention (CDC).

Julie Pilitsis, M.D., neurosurgeon with Marcus Neuroscience Institute at Boca Raton Regional Hospital.

 

In a paper published in the Journal of Parkinson’s Disease, the study’s authors indicate that this TCE-generated pollution may be a risk factor for Parkinson’s disease, the neurodegenerative disorder that predominately affects the dopamine-producing (“dopaminergic”) neurons in a specific area of the brain. Symptoms vary by individual but may include tremors, slowness and paucity of movement, limb stiffness, and gait and balance problems.

The new study’s authors reviewed a number of previous studies that suggest TCE may play a role in Parkinson’s, but they were unable to prove a cause and effect. They urge further research on the matter.

Julie Pilitsis, M.D., neurosurgeon with Marcus Neuroscience Institute at Boca Raton Regional Hospital, agrees with the authors that more research is needed before a link can be established. Dr. Pilitsis specializes in functional neurosurgery, Parkinson’s disease, essential tremor, spasticity and chronic pain. She is also dean and vice president of medical affairs at Charles E. Schmidt College of Medicine, Florida Atlantic University.

“This is a very interesting article by well-regarded clinicians in the field that compiled the data, both from patients and animal studies, suggesting that TCE may be involved in the development of Parkinson’s,” explains Dr. Pilitsis. “At this point, there appears to be a ‘signal’ -- meaning there is something there to look closer at that is intriguing -- but it is too soon to define this as a risk factor.”

TCE production in the U.S. peaked during 1970s. It was commonly used at military bases and industrial sites. Currently, up to one-third of the drinking water supplies in the U.S. may contain some TCE, says the U.S. Environmental Protection Agency. People who work with or near TCE contaminated sites should wear protective equipment and minimize exposure to the chemical. Because TCE was used extensively by the U.S. military to degrease equipment, contaminated soil and groundwater can be found near many current and former military bases, states the National Cancer Institute, part of the National Institutes of Health (NIH).

This study and others have tried to determine if TCE becomes toxic to the dopaminergic system, leading to Parkinson's.

“This study provides a synopsis of the data from humans where we just have several cases which hypothesize that TCE is involved, and animal studies which show TCE to have different effects leading to Parkinsonian-like disease in animals,” said Dr. Pilitsis. “The effects it causes in animals are loss of dopamine neurons in areas that control movement in Parkinson’s disease, increase in inflammation, and increases in alpha-synuclein which is one of the markers of PD.”

Are workers exposed to TCE-linked chemicals the most at risk?

“Based on what we know about environmental factors, the people at risk seem to be people with the most exposure and the least protection from that exposure. That means if someone is working with chemicals -- but has proper personal protective equipment -- they are at far less risk than someone whose drinking water is contaminated.”

If TCE is as common in the environment as some studies indicate, how can we avoid it or protect ourselves? 

“As with any contaminant, it is important to see how your area is affected,” says Dr. Pilitsis. “Here certain areas seem more affected than others. It is also important to understand how the environment is affected. Is it in the air? Is it in the water? Understanding where the danger comes from allows us to develop the strategies to protect ourselves.”

The U.S. Agency for Toxic Substances and Disease Registry (ATSDR), part of the U.S. Department of Health and Human Services, offers more information on where TCE is found.

What are the most significant risk factors for Parkinson's that most people should be concerned about?

“While the authors hypothesize that TCE may be related to the development of PD, there are things we know are involved,” explains Dr. Pilitsis. “These include exposure to pesticides and exposure to repeated head injury. These are two of the major two risks to date.

“There are also some known genetic markers of Parkinson’s Disease where multiple members of families can be affected. This is very rare and the majority of people with Parkinson’s do not have a family member that is affected. People generally should only become concerned about a genetic factor when more than one first degree relative is diagnosed with PD.”