A common chemical called trichloroethylene (TCE) that has been used for more than 100 years to decaffeinate coffee, degrease metal and dry-clean clothes, may be fuelling the rise of Parkinson's disease, according a new paper published in the Journal of Parkinson's Disease.
The international team of scientists detailed the widespread use of the chemical, the evidence linking the toxicant to Parkinson's, and profiled seven people who developed the disease after working with the chemical or being exposed to it in the environment.
TCE is a chemical compound that is easily absorbed through inhalation, ingestion and skin contact. Once absorbed, it quickly spreads throughout the body.
Acute exposure can cause effects such as headache, dizziness, nausea and vomiting, followed by loss of co-ordination, drowsiness and difficulty speaking. Severe exposure can lead to coma, cardiac arrhythmias and death.
Dr Dorsey – lead researcher and author of Ending Parkinson’s Disease which devotes a chapter to TCE – told The National: “People should be worried about prior exposure to trichloroethylene either through work or the environment.
“At its peak one in 12 workers in the UK were exposed to the known cancer-causing chemical.
“The lag between exposure and diagnosis of Parkinson’s disease can be 10-40 years so individuals developing Parkinson’s day could be doing so based on exposure decades ago.”
TCE is a widely used solvent employed in a number of industrial, consumer, military and medical applications.
While domestic use has since fallen, TCE is still used for degreasing metal and dry cleaning in the US.
Individuals who worked directly with the chemical have an elevated risk of developing Parkinson's. However, millions more encounter the chemical unknowingly through outdoor air, contaminated groundwater and indoor air pollution.
Dr Dorsey explained to The National that “in addition to occupational exposure, TCE can contaminate drinking water and evaporate from polluted water and readily enter homes, schools and buildings like radon does from soil) and pollute the indoor air”.
From the 1950s to the 1980s, a million Marines, their families, and civilians that worked or resided at the base were exposed to drinking water levels of TCE and perchloroethylene (PCE), a close chemical cousin, that were up to 280 times above what is considered safe levels.
“The closely related perchloroethylene (PCE) is widely used in dry cleaning in the UK. PCE has one additional chlorine atom and likely has similar toxicity to TCE”, Dr Dorsey told The National.
“In the US apartments above ground-floor dry cleaners have increased levels of PCE in their indoor air and because they are fat soluble PCE and TCE can be found in the butter and margarine in the refrigerators of residents”.
The connection between TCE and Parkinson’s was first hinted at in case studies more than 50 years ago.
In animal studies, TCE causes selective loss of dopamine-producing nerve cells, a hallmark of Parkinson’s disease in humans.
The scientists warn that "millions who live, learn, and work near former dry cleaning, military, and industrial sites are likely being exposed to toxic indoor air."
Dr Dorsey told The National that TCE has been identified as a carcinogen – a substance or agent that has the ability to cause cancer by damaging DNA or other important cellular processes – by the WHO and the US Environmental Protection Agency due to its ability to cause cancer.
He also highlighted that according to industry reports, China, where Parkinson's disease rates are increasing rapidly, is responsible for half of the TCE market. Despite its known risks, global usage of TCE is expected to grow by 2-3 per cent per year, indicating that the issue is not subsiding but rather escalating.
The paper suggests that this issue needs to be addressed urgently, and that TCE and other environmental pollutants should be removed from the environment to prevent further contamination and harm to public health.
