Penta-BDE

MP (1) Melamine pyrophosphate (2) Me 3-(3,5-di-t< /t-buty 1-4- PeBDPO Pentabromodiphenyl oxide (see penta-BDE)... 

There is a huge variety of PBDEs considering that there might be from one to ten bromine atoms bound to the diphenyl ether molecule. Among all the PBDEs, the commercial mixtures of decabromodiphenyl ether (deca-BDE), octabromodiphenyl ether (octa-BDE) and pentabromodiphenyl ether (penta-BDE) are the products that are most found in the environment. Related to octa-BDE and penta-BDE mixtures, their commercial use was banned in the European Union in 2004 and that year their leading manufacturers in North America stopped producing them on a voluntary basis [2], Regarding the deca-BDE mixture, since July 2008, its use has been... 

Fig. 1 PBDE structures examples (a) deca-BDE-209 (b) hepta-BDE-183 (c) penta-BDE-99...

The mixture of deca-BDE is composed almost exclusively of deca-BDE (BDE-209), with a rate of 97% or more and by 3% or less of nonabromodiphenyl ethers (nona-BDEs) and octa-BDEs. On the contrary, the commercial octa-BDE mixture usually contains between 10% and 12% hexabromodiphenyl ethers (hexa-BDEs), 44% of heptabromodiphenyl ethers (hepta-BDEs), between 31% and 35% of octa-BDEs, between 10% and 11% of nona-BDEs and <1% of deca-BDE [4]. The two compounds with a higher proportion in this mixture are, in first place, BDE-183 (2,2, 3,4,4, 5, 6-hepta-BDE) and then the BDE-153 (2,2, 4,4, 5,5 -hexa-BDE). In addition, the penta-BDE mixture, commercially known as DE-71, is primarily composed by tetrabromodiphenyl ethers (tetra-BDEs) (24—38%), penta-BDEs (50-60%) and hexa-BDEs (4-8%) being BDE-99 (2,2, 4,4, 5-penta-BDE) and BDE-47 (2,2, 4,4 -tetra-BDE) the main compounds of the mixture. Figure 1 shows different structures belonging to the three PBDE mixtures described. 

Penta-BDE and octa-BDE mixtures degradation studies in solid media in anaerobic conditions are very scarce. In the case of penta-BDE mixture, Vonderheide et al. [2] inoculated a culture with different anaerobic microorganisms in a contaminated soil by this mixture. After a short time, the major compound in the mixture, BDE-99, was almost completely degraded, as well as other PBDEs present in lower proportion (hexa-BDEs and penta-BDEs). Moreover, for the same time, it was observed an increase of the amount of BDE-47, which corresponds to the second major compound in the mixture. The authors argue that BDE-47 amount increase could be caused by the fact that it is a degradation product of other higher brominated PBDEs such as BDE-99. In fact, it was demonstrated later that BDE-47 is formed from BDE-99 degradation in anaerobic conditions [37]. 

In the case of BDE-154, the suggested degradation pathway results in different types of hydroxylated PBDEs mono- and di-OH-hexa-BDEs, mono-, di- and tri-OH-penta-BDEs, and a mono-OH-tetra-BDE. It was checked that Cyp P450 is... 

Apart from deca-BDE mixture, the two PBDE mixtures most frequently used in the past were the penta-BDE and octa-BDE mixtures. Although its use was banned in the European Union from 2004 and their production was ceased in the United States... 

Table 4 Characterization of octa-BDE and penta-BDE mixtures compounds...

Before degradation experiments were performed, a characterization of the composition of both mixtures, which is summarized in Table 4, was carried out. Note that in the case of penta-BDE mixture, due to the lack of analytical standards, it was only possible to quantify 6 of the 27 compounds present in the mixture. These compounds correspond to BDE-47, BDE-100, BDE-99, BDE-154, BDE-153 and BDE-183. These compounds are the major components of penta-BDE mixture, representing the 92.5% of the total composition, and they are usually detected in the environment. Respect octa-BDE mixture, two compounds were detected, BDE-153 and BDE-183, which correspond to the major components of the mixture according to the reviewed literature [4], and probably the other compounds present in the mixture were not detected due to the lack of the corresponding analytical standards. 

Regarding the degradation of penta-BDE mixture components, Table 5 shows that there was a significant removal percentage for all components detected. BDE-183, which corresponds to the highest brominated component and the less abundant... 

Table 5 Degradation and removal percentages by T. versicolor for the detected components of octa-BDE and penta-BDE commercial mixtures...

In the case of deca-BDE mixture, the formation of less brominated compounds was not detected for any of the samples (time of degradation corresponding to 24, 36, 60, 84 and 182 h). Regarding octa-BDE and penta-BDE mixtures, the analysis of samples at time 168 h did not detect an increase in concentration for any of the components present in each of the mixtures or the formation of any PBDE not present in the original composition of both mixtures. Therefore, the results obtained for the three mixtures demonstrated that the PBDEs degradation by the fungus does not follow the reductive debromination pathway, which is logical because this... 

The methoxy-polybromodiphenyl ethers (MeO-PBDEs) were analyzed together with PBDEs by GC-MS. The GC-MS methodology is optimized for the detection and quantification of eight different congeners including the 5-MeO-tetra-BDE-47, 6-MeO-tetra-BDE-47, 4-MeO-tetra-BDE-49, 2-MeO-tetra-BDE-68, 5-MeO-penta-BDE-99, 5 -MeO-penta-BDE-100, 4 -MeO-penta-BDE-101 and 4 -MeO-penta-BDE-103. 

The two OH-PBDEs detected indicate that the degradation pathway of octa-BDE and penta-BDE mixtures by the fungus corresponds, in both cases, to a hydroxyl-ation of the PBDE compounds. In the case of deca-BDE mixture, it was not possible to detect any hydroxylated product, but it cannot be excluded the formation of OH-PBDEs and their subsequent degradation for a time lower than 24 h. Therefore, it is possible that deca-BDE degradation by the fungus also occurs through the progressive hydroxylation of the compound, but it would be necessary to have results from treatment times of 12 h to confirm this possibility. 

No mortality was found in any embryo exposed to the controls. On the contrary, all the embryos exposed to the non-diluted samples of penta-, octa-, and deca-BDE commercial mixtures were dead after 24 h (Fig. 10). When the untreated PBDEs samples were diluted at 50%, a gradient of toxicity was observed penta > octa > deca. After dilution at 5%, no embryos exposed to untreated samples were dead. In agreement with our results, it has been demonstrated that the toxicity of deca-BDE is commonly lower than for octa- and penta-BDE commercial products exposures with mammalian models [64]. The different toxicity found in mammalian models and also in zebrafish should be related to the higher accumulation of lower brominated congeners in the body, because of their greater partitioning and retention in lipid-rich tissues and lower rates of metabolism and elimination in relation to deca-BDE. 

Of 47 congeners included in the analytical work, eight different PBDEs were detected, ranging from tetra- to deca-brominated compounds tetra-BDE-47, penta-BDE-99, penta-BDE-100, penta-BDE-118, hexa-BDE-153, hexa-BDE-154, hepta-BDE-183, and deca-BDE-209. However, BDE-99 could not be quantified due to coelutions with breakdown products of HBCD. This coelution has been previously described by Covaci et al. [32]. 

This article reports on two related pieces of news firstly that Albemarle Corp. of the USA has introduced a new reactive flame retardant, Saytex RX 8500 , as a replacement for pentabromodiphenyl ether (penta-BDE) in the production of flame-retardant PU foam. Secondly that Great Lakes Chemical Corp., the only manufacturer of penta-BDE, has announced plans to voluntarily phase out and cease production of this, and also octa-BDE, at the end of 2004. 

The replacement of established chemistries with newer ones is one of the classic drivers of change in the chemical industry. One of the current hotbeds of this kind of change is the replacement of brominated flame retardants in polymer formulations. The brominated flame retardants under the most scrutiny have been polybrominated diphenyl ethers, particularly penta- and octabromodiphenyl ether, which have been shown to be persistent in the environment and to bioaccumulate. Great Lakes Chemical is voluntarily phasing out penta- and octa-BDEs by the end of next year. The phaseout is made possible by the clean bill of health granted by EPA for Firemaster 550, a replacement for penta-BDE in flexible PU applications. BRG Townsend claims the phaseout of penta-BDE and octa-BDE is not as earth shattering as would be an exit from deca-BDE, a styrenics additive that is produced in the highest volume of the PBDEs. 

In an unprecedented step, the European Parliament has voted to ban two chemicals for which risk assessments are still pending. The chemicals, octabromodiphenylether and decabromodiphenyl ether, were lumped together with penta-BDE during a debate on the EC s proposed ban on that chemical, which is based on a completed risk assessment. All three chemicals are used as flame retardants. Parliamentarians backed the call to extend a ban on penta-BDE to octa-BDE, which is used in office equipment and domestic electrical appliances, by mid-2003. It is claimed that initial results of the ongoing risk assessments already indicate that the chemical is an environmental and public health hazard. MEPs have set a 2006 deadline for banning deca-BDE, adding that the ban should not come into force if the final results of the risk assessment show that deca-BDE is harmless. EUROPEAN PARLIAMENT... 

The rate at which PBDE concentrations have increased in the environment and in humans has been of considerable interest. Temporal trend studies from Europe have indicated that PBDE levels in human milk increased markedly from 1972 to 1997, doubling every 5 years [38]. Since 1997, the PBDE levels in human milk have decreased somewhat [39]. These recent ameliorations may be the result of changes in industrial practices in Europe. The European Commission, for example, has phased out the use of the commercial penta-BDE product because of concerns about its potentially adverse human health effects. Now, > 95% of the current global demand for the penta-BDE product... 

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