Polybrominate fire retardants

The challenge was to avoid the use of hazardous brominated fire retardants such as polybrominated biphenyl (PBB) and pentabromodiphenyl ether (PBDE). The first strategy was to replace PBB and PBDE with tetrabromo-bisphenol-A (TBBA). This has a much lower toxicity, but is still a brominated fire retardant with safety concerns. An improvement... 

A new study by three environmental chemists in Canada is the first to measure the levels of polybrominated diphenyl ethers (PBDEs) in the environment. PBDEs are commonly used as fire retardants in plastics, and have been found by the researchers to be accumulating rapidly in animals in the Arctic. Details of the study and its unhappy findings are presented here. 

Polybrominated biphenyls (PBBs) Contaminant Fire retardant inadvertently substituted for feed supplement in Michigan livestock loss, undetermined effect on human health... 

O Keefe PW. 1978. Fonnation of brominated dibenzofurans from pyrolysis of the polybrominated biphenyl fire retardant, Firemaster FF-1. Environ Health Perspect 23 347-350. 

Robertson LW, Chittim B, Safe SH, et al. 1983b. Photodecomposition of a commercial polybrominated biphenyl fire retardant High-resolution gas chromatographic analysis. J Agric Food Chem 31 454-457. 

Robertson LW, Safe SH, Parkinson A, et al. 1984b. Synthesis and identification of highly toxic polybrominated biphenyls in the fire retardant Firemaster BP-6. J AgricFood Chem 32 1107-1111. 

Polybrominated and polychlorinated biphenyls. Chemicals that have various industrial uses, for example as fire retardants and electrical insulators. They are persistent if released into the environment, peripheral neuropathy... 

As with polychlorinated biphenyls (PCBs). polybrominated aromatic compounds have been used in industry since the early twentieth century. The fire retardant properties of polybrominated and polychlorinated biphenyls and biphenyl ethers, for example, led to their use in building materials, furniture, clothing, and other consumer items. However, the 1970s discovery in Michigan of polybrominated biphenyls (PBBs) in feed for livestock, and subsequently in meat and dairy products, led to suspension of the use of PBBs in 1979. 

First of all, halogen-based fire retardant additives (especially bromin-ated compounds associated with the antimony trioxide) are widely used. These systems release obscuring, corrosive and toxic smoke when they perform their fire retardant action. More, some of them release super toxic compoimds ( dioxins and polybrominated dibenzofurans) when exposed to heat during manufacturing or in fire. A continuous trend is the development of polymeric materials with reduced fire hazard, in order to meet the requirement of the international regulations (5th OECD Draft Status report (04/1993) and UN Environmental Program 1st Draft Report (01/1993)). 

Another important fire retardant is polybrominated biphenyl, PBB, which is both intrinsically toxic and can form PBDF and/or PBDD in pyrolysis or combustion/ Today, however, its use is highly limited, but it has been widely used in the past. 

Many ways have been developed to decrease the inflammability of cured UPRs. The most important method consists of incorporating brominated raw materials or adding brominated fire retardants. The use of brominated compounds, in particular polybrominated diphenyl ether, has been criticized for toxicological reasons [103]. As the source of bromine in UPRs, 2,3-dibromo-2-butene-l,4-diol (Scheme 19) ... 

BFRs are one of the last classes of halogenated compounds that are still being produced worldwide and used in high quantities in many applications. In order to meet fire safety regulations, flame retardants (FRs) are applied to combustible materials such as polymers, plastics, wood, paper, and textiles. Approximately 25% of all FRs contain bromine as the active ingredient. More than 80 different aliphatic, cyclo-aliphatic, aromatic, and polymeric compounds are used as BFRs. BFRs, such as polybrominated biphenyls (PBBs), polybrominated diphenyl ethers (PBDEs), hexabromocyclododecane (HBCD), and tetrabromobisphenol A (TBBPA), have been used in different consumer products in large quantities, and consequently they were detected in the environment, biota, and even in human samples [26, 27]. 

Other brominated compounds of environmental concern are also chiral. Polybrominated biphenyls, like PCBs, were used as capacitor fluids in mixtures of congeners (e.g. Fire-master), and are also atropisomeric [4]. While HBCDD is the most common chiral brominated flame retardant, others exist, such as 2,3-dibromopropyl-2,4,6-tribromophenyl ether (Figure 4.7). As of this writing, little is known about environmental occurrence, fate, and effects of these other chiral flame retardants, and with one exception [5] nothing has yet been published on their enantiomers. 

The flame retardants, polybrominated diphenyl ethers or PBDEs, exemplify both the benefits and downsides of the modern chemical economy. Every year manufacturers of TVs, computers, furniture, electrical wires, draperies, and other products add chemical flame retardants to their products to protect the public from the dangers of fire. But in adding PBDE flame retardants to their products they have created, however unintended, another public hazard—exposing humans and animals across the globe to hazardous chemicals. 

The findings of these two fires indicate that the chronic toxicity potential from dioxins and fiirans is highly overestimated and that the contribution of polybrominated dioxins and fiirans released by the flame-retarded plastics is negligible. 

Organic Bromine. This is an efficient flame retardant that can be greatly syner-gized by addition of antimony trioxide. Since aliphatic bromine is too unstable for plastic processing, preferred compounds are polybrominated diphenyl ethers for thermoplastics, and tetrabromo bisphenol A and tetrabromophthalic anhydride for epoxies and polyesters. In a fire, it does produce smoke and toxic corrosive gases, so this must be considered in specific applications. In Europe, environmental concerns may limit the use of bromine. 

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