ABSTRACT
Owing to advances in polymer science over the past 50 years, a large number of polymers with differing properties have been developed for daily applications ranging from clothing and furniture to electronics, vehicles, and computers. However, most of these polymers are petroleum-based and hence are ammable. In order to reduce ˆre risks and meet ˆre safety regulations, certain chemicals collectively known as ame retardants are applied to combustible materials such as plastics, wood, paper, and textiles [1]. Currently, there are more than 175 compounds or groups of compounds with known ame-retarding properties, which are generally divided into four classes: inorganic, halogenated organic, nitrogen-containing, and phosphorus-containing compounds [2]. Among the halogenated ame retardants, brominated compounds comprise the largest market share because of their lower decomposition temperatures, higher performance efˆciency, and low cost [2,3]. Thus, brominated ame retardants (BFRs) have been extensively used to improve the ˆre resistance of materials such as plastics, textiles, furnishing foam, and electronic circuit boards [4]. Based on their use in the chemical industry, BFRs can be classiˆed as either reactive or additive. Reactive BFRs such as the tetrabromobisphenol A (TBBPA) are covalently bound to the polymer matrix. Compared to their reactive counterparts, additive BFRs are not chemically bound to the product and therefore tend to migrate out of the product much more easily and are thus more likely to be released into the environment. Examples of additive BFRs include polybrominated diphenyl ethers (PBDEs), polybrominated biphenyls (PBBs), and hexabromocyclododecanes (HBCDs). Production of PBBs in the United States was phased out in the 1970s after a farm product contamination incident in Michigan [5]. In turn, production of PBDEs has increased, peaking in the mid-1990s [6].
