Trichloroethylene exposure linked to Parkinsonism

Industrial workers who worked with trichloroethylene (TCE) may face a greater risk for parkinsonism, a study by a team of University of Kentucky researchers shows.

The team, led by Don M. Gash and John T. Slevin of the UK College of Medicine, identified a number of industrial workers who exhibited symptoms of parkinsonism, a group of nervous disorders with symptoms similar to Parkinson's disease. The workers had experienced long-term exposure to TCE, a degreasing agent widely used in industry that also has been found in drinking water, surface water and soil due to runoff from manufacturing sites where it has been used.

The researchers report their findings in the online version of Annals of Neurology, the official journal of the American Neurological Association.

The workers were identified during a clinical trial of 10 Parkinson's disease patients when one patient expressed concern that his long-term job-site exposure to TCE may have contributed to the disease. The patient noted some of his co-workers also had developed Parkinson's.

The other two individuals with Parkinson's had at least 25 years of occupational exposure to TCE, including both inhalation and physical contact by submerging unprotected arms and forearms in a TCE vat or touching machine parts that had been cleaned in the chemical.

Further examination of other co-workers who with long term exposure to TCE identified 14 individuals with marked parkinsonism symptoms, including significant reductions in fine motor hand movements than age-matched controls. Other individuals showed milder features of the condition when compared to the controls.

The researchers also used an animal model that showed reductions in an enzyme important to energy production and degenerative changes in certain dopamine neurons following exposure to TCE.

The researchers acknowledge the study is not a large-scale epidemiological investigation but assert that the results demonstrate a strong potential link between chronic TCE exposure and parkinsonism.

"It will be important to follow the progression of movement disorders … over the next decade to fully assess the long-term health risks from trichloroethylene exposure," they state.

"(TCE) is implicated as a principal risk factor for parkinsonism based on its dopaminergic neurotoxicity in animal models, the high levels of chronic dermal and inhalation exposure … by the three workers with Parkinson's disease, the motor slowing and clinical manifestations of parkinsonism in co-workers clustered around the trichloroethylene source, and the mounting evidence of neurotoxic effects in other reports of chronic trichloroethylene exposure," the researchers assert.