Report of the Persistent Organic Pollutants Review Committee on the work of its tenth meeting
Risk profile on decabromodiphenyl ether (commercial mixture, cdecaBDE)
At its tenth meeting, by its decision POPRC-10/2, the Persistent Organic Pollutants Review Committee adopted a risk profile for decabromodiphenyl ether (commercial mixture, c-decaBDE) on the basis of the draft contained in the note by the secretariat (UNEP/POPS/POPRC.10/3). The text of the risk profile, as amended, is set out in the annex to the present addendum. It has not been formally edited.
(commercial mixture, c-decaBDE) RISK PROFILE
Prepared by the ad hoc working group on decabromodiphenyl ether
on Persistent Organic
Risk profile on decabromodiphenyl ether (commercial mixture, cdecaBDE) 1
Executive summary 4
1.1Chemical identity of the proposed substance 6
1.2Conclusion of the Review Committee regarding Annex D information 7
1.3Data sources 7
2.1.1Production, trade, stockpiles 8
2.1.3Releases to the environment 10
1.5Environmental fate 11
2.1.5Degradation and debromination 12
2.1.6Bioavailability and tissue distribution 14
2.1.8Potential for long-range environmental transport 18
2.1.9Environmental levels and trends 19
2.1.10Human exposure 21
1.7Hazard assessment for endpoints of concern 23
2.1.11Toxicity to aquatic organisms 23
2.1.12Toxicity in soil organisms and plants 25
2.1.13Toxicity in birds 25
2.1.14Toxicity in terrestrial mammals 26
2.1.15Human toxicity 28
2.1.16Mixture toxicity and combined effects of multiple stressors 29
Commercially available decabromodiphenyl ether (c-decaBDE) is a polybrominated diphenyl ether (PBDE) formulation consisting of decabromodiphenyl ether (BDE-209), with small amounts of nonabromodiphenyl ether and octabromodiphenyl ether. C-decaBDE has been under investigation for its potential health and environmental impacts for more than a decade and has been subject to restrictions and voluntary risk management actions in some countries and regions.
C-decaBDE consumption peaked in the early 2000's, but c-decaBDE is still used worldwide. CdecaBDE is used as an additive flame retardant, and has a variety of applications including in plastics/ polymers/composites, textiles, adhesives, sealants, coatings and inks. C-decaBDE containing plastics are used in housings of computers and TVs, wires and cables, pipes and carpets. It is used in commercial textiles, mainly for public buildings and transport, and in textiles for domestic furnitures. Emissions of c-decaBDE to the environment occur at all its life cycle stages, but are assumed to be highest during service-life and in the waste phase. Emissions from industrial point sources can also be significant. Use of c-decaBDE in the production of textiles and electronics lead to emissions to the environment and transboundary air pollution either directly from articles or during production and disposal.
BDE-209 has low water solubility (< 0.1 µg/L at 24 °C) and in the environment it adsorbs strongly to organic matter and readily partitions to sediment and soil. It is very persistent and reported environmental half-lives in these media typically exceed 180 days.
BDE-209 is widespread and one of the most prevalent PBDEs in the global environment. When BDE-209 is detected in the environment and biota, it is typically found along with other PBDEs. Monitoring data show high concentrations of BDE-209 in sediments and soil, but is also found in biota worldwide, with high levels reported in some species. Levels are generally highest in the urban regions, near waste water discharges and in areas around electronic waste and recycling plants. In air, BDE-209 binds to particles that protect the chemical from photolytic degradation and it can be transported over long distances. The estimated atmospheric half-life is 94 days, but can exceed 200 days. BDE-209 is also detected in environmental and biological samples from remote regions and is one of the predominant PBDEs in Arctic air and deposition samples. Temporal trend data of BDE-209 in Arctic air and some Arctic organisms for 2002-2005 showed increasing levels, but levels may now be stabilizing.
BDE-209 has limited bioavailability because of its large size that constrains its ability topass cell membranes via passive diffusion. However, biomonitoring data shows that BDE-209 is bioavailable and is taken up by humans and other organisms. BDE-209 has been found in a variety of different organisms and biological matrices including human blood serum, cord blood, placenta, fetus, breast milk and in milk of lactating cows. In some species reported levels are close to reported adverse effect concentrations. In rodents and birds, small amounts of BDE-209 are shown to cross the blood-brain barrier and enter the brain. There is also evidence of transfer of BDE-209 from adult stages to eggs in fish and birds and of effective transport through the placenta to foetus in mammals. For humans, the available intake estimates for BDE-209 also point out the importance of dust exposure, particularly for small children. Higher levels of PBDEs and BDE-209 are reported in toddlers and young children than in adults. In aquatic organisms intake via diet appears to be the most important exposure route.
Several lines of evidence show that BDE-209 is bioaccumulative, at least in some species. The equivocation in the available bioaccumulation data largely reflects species and tissue differences in uptake, metabolism and elimination, as well as differences in exposure and also analytical challenges in measuring BDE-209.
Debromination of BDE-209 in environmental matrices and biota to more persistent, toxic and bioaccumulative PBDEs including those already listed under the Stockholm Convention (POP-BDEs) is considered to be of concern in a number of assessments. Several PBDE congeners that are not part of any commercial mixture have been identified mainly in biota but also in the environment and are considered to provide evidence for debromination of BDE-209. Due to debromination of c-decaBDE and past releases of commercial penta- and octabromodiphenyl ether organisms are often exposed to a multitude of PBDEs.
BDE-209 toxicity studies provide evidence for potential adverse effects to reproductive health and output in a number of species as well as developmental and neurotoxic effects. BDE-209 and/or its degradation products may also act as endocrine disruptors and affect thyroid hormone homeostasis. On the basis of common modes of action (not fully established)and common adverse outcomes, there is concern that BDE-209 and other PBDEs may act in combination, in an additive or synergistic manner and induce developmental neurotoxicity in both humans and wildlife at environmentally relevant concentrations. Observed effect concentrations for increased mortality in birds and developmental effects in frogs derived from controlled laboratory studies raise concern that adverse effects may occur at environmentally realistic concentrations.
The high persistence of BDE-209 combined with the simultaneous exposure of organisms to a wide range of PBDEs and the fact that endocrine disruptors like BDE-209 and/or its degradation products may elicit adverse effects even at low environmental levels increase the likelihood for longterm adverse effects.
Based on the available evidence it is concluded that c-decaBDE with its main constituent BDE-209, is likely, as a result of its longrange environmental transport, to lead to significant adverse human health and environmental effects, such that global action is warranted.