Brominated flame retardants (BFRs) have routinely been added to consumer products for several decades in a successful effort to reduce fire-related injury and property damage. Recently, concern for this emerging class of chemicals has risen because of the occurrence of several classes of BFRs in the environment and in human biota. The widespread production and use of BFRs; strong evidence of increasing contamination of the environment, wildlife, and people; and limited knowledge of potential effects heighten the importance of identifying emerging issues associated with the use of BFRs. In this article, we briefly review scientific issues associated with the use of tetrabromobisphenol A, hexabromocyclododecane, and three commercial mixtures of polybrominated diphenyl ethers and discuss data gaps. Overall, the toxicology database is very limited; the current literature is incomplete and often conflicting. Available data, however, raise concern over the use of certain classes of brominated flame retardants.

Elevated levels of polybrominated diphenyl ethers (PBDEs), a type of brominated flame retardant, were recently detected in U.S. nursing mothers' milk. These halogenated compounds chemically and toxicologically resemble others such as polychlorinated biphenyls (PCBs), whose route of intake is almost exclusively through food of animal origin. This study is the first to report the levels of PBDEs in U.S. foods in a market basket survey of 30 food types (total of 32 food samples) from three major supermarket chains in Dallas, TX. Food samples were almost exclusively foods of animal origin: meat, fish, and dairy products. Thirteen PBDE congeners were measured for each sample. Levels were then compared to existing PBDE food studies from other countries where available. In this study, levels of PBDEs are highest in fish, then meat, and lowest in dairy products; median levels were 1725 (range 8.5-3078), 283 (range 0.9-679), and 31.5 (0.2-1373), parts per trillion (ppt), or pg/g, wet weight, respectively. Nonfat milk did not have any detectable PBDE levels. In fish, PBDE congener 47 (2,2',4,4'-tetraBDE) contributes up to 70% of the total PBDEs, followed by congeners 100 (2,2',4,4',6) and 99 (2,2',4,4',5). In meat congener 99 predominates, followed by 47. In dairy, BDE 47 predominates followed by 99. U.S. food PBDE levels measured in this study are higher than reported in two other published market based studies from Spain and Japan. Although these findings are preliminary and will be updated with analyses of new samples, they suggest that food is a major route of intake for PBDEs.

2,2',4,4'-Tetrabromodiphenyl ether (BDE 47) is present in commercial mixtures of polybrominated diphenyl ethers (PBDEs), which are used as flame retardants in a wide variety of consumer products. Despite its small contribution to PBDE global production and usage, BDE 47 is the major congener found in environmental samples and human tissue. No human data are currently available regarding the toxicokinetics of BDE 47 either as an individual congener or in the commercial mixture. Because previous studies have suggested potential toxicokinetic differences between rodent species, this study was conducted in an effort to fully characterize absorption, distribution, and excretion parameters following a single dose with respect to dose, time, and route of exposure in female C57BL/6 mice. Over 80% of the administered dose was absorbed after oral or intratracheal administration, whereas approximately 62% was absorbed when the dose was applied dermally. Disposition was dictated by lipophilicity as adipose and skin were major depot tissues. BDE 47 was rapidly excreted in the urine and feces. Of particular interest was the amount of parent compound found in the urine, which was a major factor in determining an initial whole-body half life of 1.5 days after a single oral exposure. Elimination, both whole-body and from individual tissues, was biphasic. Initial half-lives were 1-3 days, whereas terminal half-lives were much longer, suggesting the potential for bioaccumulation. This toxicokinetic behavior has important implications for extrapolation of toxicological studies to the assessment of health risk in humans.