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★Mark us as a preferred sourceThere is a group of chemicals that was withdrawn from the European market between 2004 and 2006, has not been produced in the EU for well over a decade, and is nevertheless still present in Danube sediments, in the snowpack of the High Tatras, in sewage sludge, in office air and in a Svalbard ice core. The story of brominated flame retardants — specifically polybrominated diphenyl ethers, or PBDEs — is the textbook case of what “legacy contamination” actually means.
In June 2026, Environmental Research published a systematic review that pooled data from 181 European studies to answer one question: how far has Europe actually got in eliminating PBDE contamination? The short answer is: considerably less far than the regulatory dates would suggest.
What PBDEs are, and why they ended up in everything
PBDEs are synthetic bromine-containing compounds that were blended into electrical and electronic equipment, textiles, plastics, cable insulation, vehicle components and foams as flame retardants. The function was genuinely useful: they slowed ignition and bought people time to escape. The problem is that they were not chemically bonded to the host material, only mixed into it — so they could escape continuously throughout the product’s service life, and especially once it became waste.
Estimated global production between 1970 and 2005 was 1.3–1.5 million tonnes. That mass is still somewhere: in products, in landfills, in river sediments, in soils.
Three commercial mixtures were used — penta-, octa- and deca-BDE — and all three are now listed under the Stockholm Convention. In the EU, penta- and octa-BDE were banned in 2004 and deca-BDE in 2006. The group is persistent, bioaccumulative, toxic and capable of long-range atmospheric transport. In 2024–2025, EFSA’s food chain contaminants panel reaffirmed that current dietary exposure raises a health concern across all age groups, with neurodevelopmental and endocrine effects as the critical endpoints.
A review built from 181 studies
The research team — drawing on the University of Sharjah, the University of Oulu, VSB Technical University of Ostrava and the University of Belgrade — worked to PRISMA methodology with a pre-registered protocol. Searches across three databases (Ovid, Scopus, Web of Science) returned 1,764 records; after screening, 181 studies remained. The data were organised across six environmental compartments: air, water, sediment, soil, snow/firn and sewage sludge.
What emerges is not an even contamination map but a very sharp pattern: what matters is which compartment you look in.
The memory of the environment: where the contamination stayed
Water is essentially a transit compartment. Concentrations are generally low and frequently below detection limits — except where fresh input arrives: downstream of wastewater treatment discharges, in stormwater runoff, after combined sewer overflows, below industrial outfalls. Water is not a store; it is a conveyor belt.
Sediment, by contrast, is a store. The most consistent finding of the review is that river, estuarine, lake and marine sediments are the principal long-term sink for PBDEs. Sediment cores function as archives: dated cores from Lake Greifensee in Switzerland, from English lakes and from the Baltic preserve the emission curve that rises from the mid-20th century and peaks in the 1990s.
Sewage sludge is a category of its own. Latvian data put the sum of eight congeners at 78–714 ng/g dry weight, of which 89–98 % was a single compound, BDE-209 — while surface waters and sediments in the same catchment were close to nothing. For waste management this is critical: sludge concentrates the contamination, and if it goes to agricultural land, it takes the contamination with it.
Soil mainly reflects atmospheric deposition. Concentrations tend to stay in the surface layers and rise where there is urban loading, flood-borne sediment deposition or sludge application. Air is both a transport medium and an indicator — and here there is good news: several long-term European monitoring series show a clear decline.
The congener that refuses to disappear: BDE-209
The recurring character in this review is BDE-209, the main component of the deca-BDE mixture. It dominates sediments, sewage sludge, suspended particulate matter, stormwater and almost every industrially or urban-influenced system. The reason is physical: it binds strongly to particles and organic matter, so it goes wherever dust and sludge go.
The lighter congeners — BDE-47 and BDE-99 — are more common in air, soils and living organisms, because they are more volatile and more bioavailable. This split explains why measuring a single compartment can be badly misleading: look only at water, and you will get a “clean” result even where the sediment is heavily contaminated.
There is a further lesson here. BDE-209 is analytically difficult — poor extraction recovery, susceptibility to degradation during sample preparation — and some studies simply omitted it. The review’s authors warn that this may have led to underestimation of total burdens, precisely in the most contaminated, particle-rich samples.
Where brominated flame retardants re-enter the system today
This is the point at which the topic lands on the waste management desk. According to the review, the bulk of current release does not come from manufacturing but from products in use and, above all, at end of life.
The source types listed will be familiar to anyone working in the sector: waste treatment facilities, incinerators, landfills, WEEE processing, metal recycling and vehicle dismantling. Norwegian measurements found airborne concentrations at waste-handling facilities orders of magnitude above residential levels; at Finnish WEEE recycling plants, occupational exposure was dominated by BDE-209, and meaningful improvement came only after ventilation and dust control were upgraded.
The most sensitive point, however, is recycling. Researchers have detected brominated compounds characteristic of electronic waste in black food-contact plastics — thermo cups, kitchen utensils. In other words, the contamination does not simply “leave” the system; it can re-enter consumer products through material flows. The Czech Svitava River shows the same thing spatially: the sediment contamination peak sat downstream of a former textile factory, years after the plant had closed.
The indoor air we rarely talk about
One of the review’s most important messages for human exposure is that we spend 80–90 % of our lives indoors, and indoor concentrations are frequently orders of magnitude above outdoor levels. In Greece, one office recorded 10,848 pg/m³ in air. In Germany, total PBDE content in house dust ranged from 36.6 to 1,580 ng/g, again with roughly 90 % attributable to BDE-209.
That same German study adds nuance, though: 95–97 % of total daily intake came from diet, not from air. Indoor dust and air are significant sources, but the food chain — through persistence and accumulation in aquatic organisms — remains the principal route.
From glaciers to the Arctic
Perhaps the most striking part of the review is where these compounds turn up in places that never used a flame retardant. A Svalbard ice core preserved a deposition record from 1953 to 2005, with BDE-209 peaking between 1995 and 2005. In the ice of Italy’s Mt. Ortles glacier, BDE-209 accounted for around 47 % of the total burden, linked to air masses arriving from the Po Valley. In the snowpack of the High Tatras, the compounds were present at every elevation, and lighter congeners increased with altitude — the “cold trapping” effect.
This has an uncomfortable implication: these mountain and polar reservoirs release their load when they melt. Contamination deposited in the past represents emission events that are still ahead of us.
Hungary on the map: a single study
This is worth pausing on. The United Kingdom and Ireland are represented in the review by 31 studies, Italy by 22, Spain by 20, France by 16, Sweden by 14. Hungary is represented by one.
That study sampled two background grassland sites on the Great Hungarian Plain. The results are reassuring: airborne sums of nine congeners were near-identical at both sites, soil values ran between 18.2 and 67.4 pg/g, and the profile was dominated by BDE-47 and BDE-99 — the classic background picture from atmospheric deposition.
But two background grasslands are not a national picture. There are no Hungarian data on river sediments, sewage sludge, the surroundings of waste treatment facilities, indoor air or urban soils. On the Serbian stretch of the Danube, where measurements were taken, sediment PBDE content ranged from 0.52 to 31.21 µg/kg, with BDE-209 dominant at every sampling point and a waste-related signature identified near a landfill. There is no reason to assume the Hungarian stretch of the same river is exempt from the same processes — we simply have not looked.
The data gap is not a neutral state. The review itself warns that the evidence base is geographically uneven, and that differences between countries partly reflect research activity rather than actual contamination.
The delicate balance of the circular economy
The regulatory direction is unambiguous. Regulation (EU) 2019/1021 on persistent organic pollutants is the framework; the RoHS Directive caps PBDE content at 0.1 % by weight in homogeneous materials in electrical and electronic equipment; REACH separately restricts deca-BDE; and Directive 2013/39/EU treats the group as priority substances in water quality legislation.
On 24 July 2025, the European Commission adopted Delegated Regulation (EU) 2025/1482, further lowering permitted trace contamination limits in articles and mixtures — while temporarily retaining higher limits for certain recycled materials.
That compromise is exactly the dilemma the sector faces daily. Extend the strict limit to recycled plastic immediately, and large material streams drop out of circulation into incineration or landfill. Do not extend it, and legacy contamination keeps circulating through material flows. There is no painless option — only the question of whether the cost is borne by today’s recycling rate or tomorrow’s contamination.
It is worth adding that regulation is not uniform within Europe either. Post-Brexit, the UK operates its own POPs regime: Great Britain has retained the earlier 500 mg/kg limit, while Northern Ireland follows the stricter EU rules under the Windsor Framework. For waste streams and secondary raw material trade, that divergence is anything but theoretical.
What we can take from this
The review’s conclusion is sober: regulation reduced the contamination but did not eliminate it. In air and background soils, declining trends are demonstrable in several places. In sediments, sludge, indoor dust and waste streams, they are not.
Four lessons follow.
Material choice is a decades-long commitment. An additive that cannot be removed at end of life stays with us for generations. This is not a PBDE-specific lesson — the same logic applies to any additive that is not chemically bound.
Measuring one compartment is not enough. The review’s strongest methodological message is that a low value in water tells you nothing about sediment, and a low value in soil tells you nothing about indoor dust. Measure one matrix, and you will misread the risk.
Waste management is now a secondary source. Landfills, incinerators, WEEE processors, vehicle dismantlers and metal recyclers do not merely inherit legacy contamination; they are active emission points. This is an occupational health and installation-emissions question as much as an environmental one.
Monitoring of replacement compounds starts now. Substitutes for PBDEs — DBDPE among them — appear repeatedly in the review, often in the same samples. If we follow the same arc (detection, concern, ban, then a survey twenty years later), we will be writing this same article in 2050 under a different acronym.
Frequently asked questions about brominated flame retardants
What are brominated flame retardants and why were they banned?
Brominated flame retardants are additives blended into electronics, textiles, plastics and foam to slow ignition. The PBDE group was banned — in the EU in 2004 and 2006 — because these compounds are persistent, accumulate in living organisms, are toxic, and travel long distances through the atmosphere.
If they were banned in 2006, why are they still found in the environment?
Because the additives were never chemically bonded to the products, so they keep escaping, especially at end of life. The 1.3–1.5 million tonnes produced between 1970 and 2005 are still present in landfills, sediments and products in use. Most current release comes from waste handling and recycling rather than manufacturing.
Which environmental compartment accumulates the most PBDE?
Sediment and sewage sludge are the main long-term reservoirs. Concentrations in water are usually low and transient, and in soil are confined to surface layers. Latvian data showed BDE-209 alone accounting for 89–98 % of PBDE content in sewage sludge, while surface water in the same catchment was essentially clean.
Does recycled plastic pose a risk because of PBDE content?
Researchers have detected brominated compounds characteristic of electronic waste in black food-contact plastics, meaning contamination can re-enter consumer products. EU Regulation 2025/1482 therefore tightens limit values, while temporarily retaining higher thresholds for certain recycled materials.
How contaminated is Hungary by international comparison?
There is no reliable answer. Only one of the 181 studies covered Hungary, sampling two background grasslands on the Great Plain, where soil values of 18.2–67.4 pg/g were recorded. There are no domestic data on river sediments, sewage sludge, waste treatment facilities or indoor air.
Source: Abass, K., Semerjian, L., Roupcová, P., Stamenovic, J., Masood, M. A., Kumari, M., Botwe, P., Suchanková, J., Sikorová, K., Šudrychová, I., Klimková, L., Chudová, D. (2026): Polybrominated diphenyl ethers (PBDEs) contamination across environmental compartments in Europe. Environmental Research, 306, 125047. Open access (CC BY). DOI: 10.1016/j.envres.2026.125047
