Industrial chemical banned in the EU linked to Parkinson’s disease

People who spend years breathing in a common chemical that is banned in the European Union may be at higher risk of developing Parkinson’s disease, a new study has found.

Trichloroethylene (TCE) is an industrial solvent used to degrease metals and dry clean clothes – but it has been illegal in the EU, with limited exceptions, since 2016 over concerns it could cause cancer and genetic defects.

In the United States, where the study took place, TCE spreads easily in the air and can also be found in soil and water.

The chemical has been linked to Parkinson’s, an age-related degenerative brain condition, in the past. But while most research focuses on TCE exposure at work, the new study covers the entire US.

It found a “small but measurable increase in Parkinson’s risk” linked to TCE exposure, said study author Brittany Krzyzanowski, a research assistant professor at the US-based Barrow Neurological Institute.

Her team analysed data for nearly 222,000 older adults who were newly diagnosed with Parkinson’s between 2016 and 2018, and compared them with more than 1.1 million people without the disease.

The researchers estimated people’s outdoor exposure to TCE using local environmental data for their home ZIP codes, and divided people into 10 groups based on their exposure levels.

After taking other risk factors into account, people with the highest TCE exposure were 10 per cent more likely to develop Parkinson’s than people with the lowest exposure, according to the study, which was published in the journal Neurology.

Parkinson’s affects about 10 million people worldwide. The symptoms, including a tremor in the hands, limb stiffness, balance problems, and slowness of movement, typically develop slowly over several years. There is currently no cure.

The researchers also homed in on the areas around the top three TCE-emitting facilities in the US – and found that the risks were higher closer to these sites.

“While the increased risk was modest, the sheer number of people exposed to TCE in the environment means the potential public health impact could be substantial,” Krzyzanowski said in a statement.

While TCE is not allowed in the EU, it remains controversial in the US. The Biden administration banned its use last year, but the Trump administration has repeatedly postponed the rule, as recently as August.

The latest findings do not prove that TCE exposure causes Parkinson’s, only that the two are related.

The study also has some limitations, notably that it focused on older adults and may not capture the risks for younger people or those with early-onset Parkinson’s. Levels of TCE in the air were also drawn from a single point in time, meaning they may not reflect people’s exposure over their lifetimes.

But the results add to a growing body of evidence that Parkinson’s may be predominantly a disease of our environments, with chemicals and pollution playing a role along with genetics.

In a separate study last year, Krzyzanowski identified air pollution as a risk factor for Parkinson’s. Other research implicates pesticides such as paraquat.

Krzyzanowski called for “stronger regulations and more monitoring of industrial pollutants” to curb the risks.