A new scientific review reveals that chemical substances banned more than half a century ago remain present in different environments across Europe, including in the air, water, sediments, soils, snow, and sludges. The researchers warn that these persistent contaminants continue to circulate in ecosystems, despite regulatory restrictions introduced decades ago.
The study, led by Professor Khaled Abass, of the College of Health Sciences at the University of Sharjah, analyzed the presence of polybrominated diphenyl ethers (PBDEs), substances used for decades as flame retardants in electronic equipment, textiles, plastics, vehicles, furniture, and building materials. The analysis covered studies conducted in 25 European countries and identified concentrations of these compounds in both areas affected by human activity and in remote environments.
“One of the most important conclusions is the predominance of BDE-209 in particle-rich matrices, including sediments, sludges, wastewater-related systems and deposition. This is important because sediments and sludges are not passive storage sites,” explains Khaled Abass.
According to the researchers, sediments can function as long-term environmental reservoirs, gradually releasing contaminants into watercourses, soils, waste management systems, and food chains. Meanwhile, compounds with a lower degree of bromination, such as BDE-47 and BDE-99, were found more frequently in air and soil samples, demonstrating that the behavior and distribution of PBDEs vary depending on the environmental compartment.
The results were published in the scientific journal Environmental Research and stem from a systematic review that brought together researchers from the University of Sharjah, the University of Oulu in Finland, the Technical University of Ostrava in the Czech Republic, and the University of Belgrade in Serbia.
The team analyzed 181 studies that met the defined criteria, covering different environmental matrices, including air, water, sediments, soils, snow and compacted snow (firn), and sludges. The review followed PRISMA guidelines for systematic reviews and also assessed the quality of the studies and the risk of bias.
“PBDEs were widely detected across Europe, in both affected environments and remote locations, with distributions strongly dependent on the matrix type,” the authors note. “Water generally showed lower and more transient concentrations, while sediments, sludges, and some soils acted as important reservoirs.”
Past Pollutants That Remain Present
The investigation shows that the presence of these compounds is not limited to former industrial zones or urban areas. PBDEs have also been identified in alpine locations, the Arctic, and other reference areas, underscoring their environmental persistence and long-distance transport capacity.
The researchers point out that these contaminants continue to be detected due to their persistence in old consumer products, recycled materials, waste streams, contaminated reservoirs, sediments, soils, and indoor environments.
The conclusions call into question the idea that a dangerous substance gradually disappears after being banned. In reality, so-called legacy pollutants can continue to circulate between different environmental compartments for decades after production and use have ended.
“European evidence also highlights a difficult tension at the level of public policy. Europe is moving toward more ambitious circular economy models, but circularity without chemical safety can, unintentionally, reintroduce legacy pollutants into circulation,” warns Khaled Abass.
The researcher adds that materials originally produced to increase fire safety can re-enter new product chains through recycling, if contaminants present in old materials are not properly monitored.
Monitoring Must Be Strengthened
Given these results, the authors advocate for more comprehensive and coordinated monitoring strategies, with tracking of different environmental matrices and greater attention to BDE-209, its transformation products, and the flame retardants used as substitutes.
“Monitoring only a single matrix, a country, or a group of congeners is no longer sufficient,” emphasizes Abass. “PBDEs circulate between interconnected systems: from products to dust, from dust to wastewater, from wastewater to sludges, from sludges to soils, and from sediments to aquatic food chains.”
The research also draws attention to indoor exposure. Indoor air and household dust remain important exposure pathways, especially in spaces with high concentrations of electronic equipment.
The researchers therefore argue that governments and regulatory bodies should pay closer attention to the presence of these pollutants in homes, offices, schools, and workplaces, given the amount of time people spend indoors.
“Europe has made significant progress in controlling PBDEs. However, the contamination history shows that decisions taken in the past continue to influence current and future exposure. PBDEs are therefore not merely pollutants of the past. They are legacy chemical substances that remain actively present in the environment,” concludes Khaled Abass.
