Toxic flame-retardant compounds that were banned two decades ago continue to contaminate sediments and soils across Europe, a new study shows.
But it’s their persistence in food chains and indoor environments that has scientists most concerned when it comes to human exposure.
Those are the results of a systematic review just published in Environmental Research.
The chemicals in question are PBDEs (polybrominated diphenyl ethers), which were once popular for their flame-retardant properties.
They were added to building materials, electronics, cars, planes, furniture textiles and cushioning – pretty much anything that was at risk of setting fire.
They worked quite well for this purpose, but in the 1990s, their ability to accumulate in nature – and in human bodies – was starting to show.
A Swedish study showed PBDEs were present in human breastmilk, with concentrations growing rapidly between 1972 and 1997. A study in the US in 2002 found even higher levels of contamination there.
It’s for this reason, they were banned in most parts of the world, including the US and Europe, in the early 2000s.
Beyond their presence in our bodies and the environment, though, the actual health effects of PBDEs (much like forever chemicals and microplastics) are difficult to pin down.
Most of what we know about their toxicity is from small studies on animals in labs, or from observational studies of human populations, which can only reveal statistical links, not a cause.
But the results of those studies – linking PBDE exposure to liver, thyroid, and breast cancer, and, potentially, reproductive health – were sufficient to drive the European Union to begin banning various forms of PBDE in 2004.
Now, a team of scientists has looked at 181 existing, peer-reviewed studies assessing PBDE contamination across Europe to gauge what difference those policies have made.
The results were grim: PBDEs persist across European environments, from offices in Spain to remote alpine snow in Slovakia.
“Europe has made major progress in controlling PBDEs,” says the study’s lead author, Khaled Abass, an environmental toxicologist based at the University of Sharjah in the UAE.
“However, the contamination record shows that past chemical decisions continue to shape present and future exposure. PBDEs are therefore not simply pollutants of the past. They are legacy chemicals with an active environmental presence.”
Outdoor concentrations tended to be far lower than indoor environments, and, unsurprisingly, sites with the greatest contamination loads were those with the heaviest human industrial activity: cities, factories, landfills.
BDE-209 was generally the most dominant PBDE contaminant in sediments and wastewater sludge, while BDE-47 and BDE-99 were the more prominent culprits in air and soils.
Multiple studies in the review suggested PBDE loads in air and soil were declining, likely as a result of the bans.
It’s not just Europe, either. A 2024 study found PBDE in fish in the US, despite the chemical being banned 20 years earlier.
Legacy materials (think old furniture and tech), recycled products, waste streams (including human sewage, but also landfills), and contaminated reservoirs (like former textile factories, fire-affected land, and scrapyards) continue to release PBDEs into the environment.
“PBDEs move across connected systems: from products to dust, from dust to wastewater, from wastewater to sludge, from sludge to soils, and from sediments to aquatic food webs,” Abass says.
He points out that exposure to PBDEs could be an ongoing issue as more people move towards circular economies – buying and selling secondhand products, recycling materials, repurposing waste (as fertilizer, for instance), even renovating old houses.
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“Circularity without chemical safety can unintentionally recirculate legacy pollutants,” he says.
“Materials once manufactured for fire safety may re-enter modern product chains through recycling if old chemical burdens are not carefully monitored.”
The study was published in Environmental Research.
This article was fact-checked by Fiona MacDonald and edited by Fiona MacDonald. While we pride ourselves on our process, we are only human. If you spot a mistake, please let us know.
