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United States Department of Agriculture

Agricultural Research Service

Title: Metabolism in the Toxicokinetics and Fate of Brominated Flame Retardants (Bfrs)-a Review

Authors
item Hakk, Heldur
item Letcher, Robert - UNIV WINDSOR, ONTARIO

Submitted to: Environment International
Publication Type: Review Article
Publication Acceptance Date: January 1, 2003
Publication Date: January 1, 2003
Citation: Hakk, H., Letcher, R.J. 2003. Metabolism in the toxicokinetics and fate of brominated flame retardants (bfrs)-a review. Environment International. 29:801-828.

Interpretive Summary: Brominated flame retardants (BFR) are required to be used in textiles, clothing, and electronic circuits to minimize the hazard of fire to the consumer. However, chemically they are related to the well-known environmental contaminants dioxins, furans and PCBs, therefore, may be expected to be toxic in some instances, and bioaccumulative. A summary of six abundant members of the BFR family are discussed in terms of their known absorption, distribution, metabolism and excretion (ADME) behavior in lab animals, wildlife and humans. The family members are polybrominated biphenyls, tetrabromobisphenol-A, tris(2,3-dibromopropyl)phosphate, polybrominated diphenyl ethers, bis(246-tribromophenoxy) ethane, and hexabromocyclododecane. In some groups, much is known about the ADME and toxicity, and this has lead to the banning of these substances. In this group are the polybrominated biphenyls and tris(2,3-dibromopropyl)phosphate. Interest grows each year in the ADME and toxicity of polybrominated diphenyl ethers because they are a growing environmental pollutant. The most abundant BFR is tetrabromobisphenol-A and yet almost no studies exist on its metabolism and toxicity. Finally, ADME data on bis(246-tribromophenoxy) ethane and hexabromocyclododecane is almost absent in the peer-reviewed literature. Therefore, the conclusion of this minireview is that much more species- and congener-specific ADME data is needed in the peer reviewed literature for most of the important BFR family members.

Technical Abstract: Brominated flame retardants (BFR) are required to be used in textiles, clothing, and electronic circuits to minimize the hazard of fire to the consumer. However, they are polyhalogenated aromatics, and because of their chemical similarity to dioxins, furans and PCBs, may be expected to be bioaccumulative, and perhaps, toxic. A summary of six abundant members of the BFR family are discussed in terms of their known absorption, distribution, metabolism and excretion (ADME) behavior in lab animals, wildlife and humans. The family members are polybrominated biphenyls (PBB), tetrabromobisphenol-A (TBBPA), tris(2,3-dibromopropyl)phosphate (Tris), polybrominated diphenyl ethers (PBDE), bis(246-tribromophenoxy) ethane (BTBPE), and hexabromocyclododecane (HBCDD). Of the minmal research done so far, BFRs are susceptible to several metabolic processes including, oxidative debromination, reductive debromination, oxidative cytochrome P450 mediated biotransformation and/or Phase II conjugation. Among the BFR families, the role of metabolism is best understood for PBB and Tris, and this has lead to the banning of these substances. This is not the case, however, for TBBPA, PBDE, BTBPE and HBCDD. This data is desirable because TBBPA and PBDE are the largest volumes BFRs, and in the case of PBDE, make up a growing environmental problem. Finally, ADME data on BTBPE and HBCDD is almost absent in the peer-reviewed literature. Therefore, the conclusion of this minireview is that much more species- and congener-specific ADME data is needed in the peer-reviewed literature for most of the important BFR family members.

Last Modified: 9/20/2014
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