Healthy living

Solvents linked to Parkinson's disease

Solvents linked to Parkinson s disease TCE found to increase risk of disease

Exposure to certain solvents may increase the risk of developing Parkinson's disease, a study suggests.

Researchers found that people exposed to trichloroethylene (TCE) in the workplace were up to six times more likely to develop the condition.

Parkinson's disease is a progressive neurological condition caused by the loss of brain cells that produce a molecule called dopamine.

Common symptoms of Parkinson's include tremor, stiffness, slowed movement and impaired balance, but patients may also develop difficulty walking and speaking.

The cause of Parkinson's is unknown. Genes may play a role, but fewer than one in 10 cases are linked to a single genetic mutation, and not all people with the mutation go on to develop the disease. This has led experts to suggest that environmental factors may also be involved in the development of the disease.

In the study, published in the journal Annals of Neurology, the researchers investigated whether exposure to certain chemical solvents influenced the risk of developing Parkinson's disease.

They analysed data collected from 99 sets of male twins, in which one of the pair had developed the disease. As twins are genetically similar and from similar backgrounds, it increases the likelihood that any study findings would be down to external environmental influences.

The men were questioned about their lifestyle, work and specifically about occupational tasks which would potentially expose them to chemicals previously linked to Parkinson's. They were also asked about their hobbies.

The researchers found that Parkinson's disease was six times more likely in the men who were exposed to TCE in the workplace.

Two other solvents - perchloroethylene (PERC) and carbon tetrachloride (CC14) - also tended towards increasing the risk of developing the disease, the researchers said.

No link was found between developing Parkinson's disease and exposure to the solvents toluene, xylene and n-hexane, which were also investigated in the study.

Dr Samuel Goldman of The Parkinson's Institute in Sunnyvale, California, who co-led the study, said: "Our study confirms that common environmental contaminants may increase the risk of developing Parkinson's, which has considerable public health implications."

TCE is an industrial solvent that been used in the past in paints, carpet cleaners, dry-cleaning, in coffee decaffeination and even as an anaesthetic. The use of TCE in the food and pharmaceutical industries has been banned in many parts of the world due to fears over toxicity, but it is still used as a metal degreaser. TCE is also the most reported contaminant of groundwater, the researchers said.

PERC is widely used as a dry cleaning agent.

Dr Michelle Gardner, research development manager at Parkinson's UK, said: "We still don't know exactly what causes Parkinson's. It's most likely to be a combination of genetic susceptibility and environmental factors. We already know that exposure to some chemicals including certain pesticides can slightly increase the risk of Parkinson's.

"This is the first study to show that the solvent TCE may be associated with an increased risk of developing Parkinson's.

"It is important to highlight that many of the previous uses of this solvent have been discontinued for safety reasons over 30 years ago and that safety and protection in work places where strong chemicals such as this solvent are used has greatly improved in recent years.

"Low levels of this solvent and other solvents are found in the environment from industrial and other emissions but this study only examined heavy exposure at work to the solvent.

"Further larger scale studies on populations with more defined exposures are needed to confirm the link."

This article was published on Mon 14 November 2011

Image © jwblinn -

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