Banned PBDE Flame Retardants Still Contaminate Europe, Study Finds

Toxic flame-retardant chemicals prohibited two decades ago are still contaminating soils and sediments throughout Europe, according to a new study.

Scientists are particularly concerned about what this means for human exposure, given the compounds' persistence in food chains and indoor settings.

The findings come from a systematic review published in Environmental Research.

PBDE flame retardants and their widespread use

The compounds are PBDEs, or polybrominated diphenyl ethers, which were formerly widely used as flame retardants.

They were incorporated into construction materials, electronic devices, cars, aircraft, furniture fabrics and padding – in effect, almost any product liable to catch fire.

Although they were effective in this role, evidence of their tendency to build up in the environment – and in people – began to emerge during the 1990s.

A Swedish study detected PBDEs in human breast milk, with levels increasing quickly from 1972 to 1997. A US study published in 2002 reported still greater contamination levels there.

This is why the substances were prohibited in much of the world, including the US and Europe, during the early 2000s.

Uncertain health effects of PBDE exposure

Yet, as with forever chemicals and microplastics, determining the precise health effects of PBDEs remains difficult, beyond establishing that they occur in our bodies and the environment.

Much of the evidence about their toxicity comes either from small laboratory animal studies or observational research involving human populations. Such studies can identify statistical associations, but cannot establish cause.

Nevertheless, results linking PBDE exposure with liver, thyroid and breast cancer, as well as potentially reproductive health, were enough for the European Union to start banning different forms of PBDE in 2004.

Researchers have now examined 181 existing peer-reviewed studies of PBDE contamination across Europe to assess the impact of those policies.

Their findings were bleak: PBDEs remain present in European environments ranging from Spanish offices to isolated Alpine snow in Slovakia.

"Europe has made major progress in controlling PBDEs," says the study's lead author Khaled Abass, an environmental toxicologist 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."

Where PBDE contamination persists in Europe

Levels outdoors were generally much lower than those found indoors. Unsurprisingly, the locations carrying the highest contamination loads were associated with the most intensive human industrial activity, including cities, factories and landfill sites.

BDE-209 was typically the predominant PBDE contaminant in sediments and wastewater sludge. By contrast, BDE-47 and BDE-99 were more prominent in air and soil.

Several studies included in the review indicated that PBDE concentrations in air and soil are falling, probably because of the bans.

Nor is this an exclusively European problem. A 2024 study found PBDEs in fish in the US, even though the chemical had been prohibited there 20 years earlier.

Old materials – such as ageing furniture and technology – alongside recycled goods, waste streams including human sewage and landfill sites, and contaminated reservoirs such as former textile factories, fire-affected land and scrapyards, continue to emit 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 notes that PBDE exposure may remain a concern as increasing numbers of people adopt circular-economy practices: purchasing and selling second-hand products, recycling materials, repurposing waste – for example, as fertiliser – and renovating older homes.

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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 appeared in Environmental Research.

This article was fact-checked and edited by Fiona MacDonald. Although we take pride in our process, we are only human. If you notice an error, please let us know.