Flame retardants concerns about

The use of flame retardants came about because of concern over the flammabiUty of synthetic polymers (plastics). A simple method of assessing the potential contribution of polymers to a fire is to examine the heats of combustion, which for common polymers vary by only about a factor of two (1). Heats of combustion correlate with the chemical nature of a polymer whether the polymer is synthetic or natural. Concern over flammabiUty should arise via a proper risk assessment which takes into account not only the flammabiUty of the material, but also the environment in which it is used. 

The Brominated Flame Retardants Industry Panel (BFRIP) was formed ia 1985 within the Flame Retardant Chemicals Association (FRCA) to address such concerns about the use of decabromodiphenyl oxide. Siace 1990 the BFRIP has operated as a Chemical Self-Funded Technical Advocacy and Research (CHEMSTAR) panel within the Chemical Manufacturers Association (CMA) (64). As of 1993, members of BFRIP are Ak2o, Amerihaas (Dead Sea Bromine Group), Ethyl Corp., and Great Lakes Chemical. Siace its formation, BFRIP has presented updates to iadustry on a regular basis (65,66), and has pubhshed a summary of the available toxicity information on four of the largest volume brominated flame retardants (67,68) tetrabromo bisphenol A, pentabromodiphenyl oxide, octabromodiphenyl oxide, and decabromodiphenyl oxide. This information supplements that summarized ia Table 11. 

The first HFIP-based polycarbonate was synthesi2ed from bisphenol AF with a nonfluorkiated aromatic diol (bisphenol A) and phosgene (121,122). Incorporation of about 2—6% of bisphenol AF and bisphenol A polycarbonate improved the dimensional stabkity and heat-distortion properties over bisphenol A homopolycarbonate. Later developments in this area concern the flame-retardant properties of these polymers (123,124). 

Bromine compounds are often used as flame retardant additives but 15-20ptsphr may be required. This is not only expensive but such large levels lead to a serious loss of toughness. Of the bromine compounds, octabromo-diphenyl ether has been particularly widely used. However, recent concern about the possibility of toxic decomposition products and the difficulty of finding alternative flame retarders for ABS has led to the loss of ABS in some markets where fire retardance is important. Some of this market has been taken up by ABS/PVC and ASA/PVC blends and some by systems based on ABS or ASA (see Section 16.9) with polycarbonates. Better levels of toughness may be achieved by the use of ABS/PVC blends but the presence of the PVC lowers the processing stability. 

Aromatic and aliphatic bromine compounds play an important role as industrial products, e.g. special products are widely used as flame retardants for polymeric materials (ref. 1). Because there is an increasing interest and concern about the behaviour and fate of anthropogenic compounds in the environment (ref. 2), we have studied the physical behaviour and chemical reactivity of these products which are relevant to the environment. The main object is the study of their thermal behaviour during incineration, as well as photolytic reactions. Of prime concern is... 

In addition, the concern about e-waste not only focuses on its vast quantity generated daily, but also more on the need to handle the toxic chemicals embedded in it. It is well known that e-waste contains lead, beryllium, mercury, cadmium (Cd), and brominated flame retardants (BFRs) among other chemical materials [3]. Furthermore, highly toxic chemicals such as polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and polybrominated dibenzo-p-dioxins and dibenzo-furans (PBDD/Fs) can be formed during the recycling process [4]. 

The Danish Environmental Protection Agency has started work to draft a national plan to control brominated flame retardants, and has published what officials claim to be the most exhaustive national survey analysing the flow of such substances and assessing possible substitutes for specific applications. The survey found that the major source of BFRs emissions in Denmark was from evaporation from products already in use, and underlines previous concerns about the possible harm due to bioaccumulation. Denmark is to join Sweden in urging international action to curb the use of brominated flame retardants. 

China was one of the first proponents of the Stockholm Convention, but only recently have we started to prepare the national inventory of PCDD/Fs and PCBs, which are among POPs specified by the convention. PBDEs have been extensively used as flame retardants in various products, and recently, the environmental problems associated with these compounds have become great concern. Data about the pollution status of these pollutants were extremely scarce in China due to the lack of regulations and monitoring capacity. In this chapter, sources of PCDD/Fs, PCBs, and PBDEs and their levels in the environmental media in China are summarized, based mainly on available scientific literature. The challenges for management of these compounds are also discussed. 

Concerns have been raised about the findings of chemicals, including some flame-retardants, in humans or the environment.4 5 Even though the levels found are extremely low and have not been shown to pose a risk to the environment or to human health,6-7 every effort should be made to minimize the release of chemicals from manufacture and use, where the largest potential for emissions exists. 

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 saga of brominated flame retardants offers a cautionary tale for the chemical industry.65 These chemicals, developed in the early 1970s, are used in a wide range of consumer products, such as furniture, foam, and plastic casings of electronic devices. In 1998, Swedish scientists reviewing archived human breast milk samples discovered that certain flame retardant chemicals (polybrominated diphenyl ethers, or PBDEs) had doubled in concentration in Swedish breast milk about every five years over the preceding twenty. This was a source of concern, as studies of laboratory animals had shown that PBDEs dismpt thyroid hormones. Such dismption yields neurobehavioral effects similar to those of PCBs (polychlorinated biphenyls), whose manufacture the United States banned in 1976. 

In the last few decades, with the growing public concerns about fire hazardous, environmental risks, cleaner surrounding and safe/healthy life style, considerable efforts have been made to develop an eco-friendly/green new generation of flame retardants to replace the restricted hazardous or banned ones [3,4,49, 50]. 

Meanwhile, there is mounting concern about polybromo-diphenyl ethers (PBDEs). Although use of PBDEs could potentially save lives and property in their roles as flame retardants, these compounds are now widespread in the environment, and studies have led to significant concern about their toxicity... 

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