DIOXINS AND OTHER ENVIRONMENTAL CONTAMINANTS IN FOOD
Location: Animal Metabolism-Agricultural Chemicals Research
Title: Accumulation, Whole-body Depletion, and Debromination of Decabromodiphenyl Ether (BDE-209) in Male Sprague-Dawley Rats Following Dietary Exposure
Submitted to: Environmental Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 10, 2007
Publication Date: February 22, 2007
Citation: Huwe, J.K., Smith, D.J. 2007. Accumulation, Whole-body Depletion, and Debromination of Decabromodiphenyl Ether (BDE-209) in Male Sprague-Dawley Rats Following Dietary Exposure. Environmental Science and Technology 41:2371-2377.
Interpretive Summary: Polybrominated diphenyl ethers (PBDE) are additive flame retardants used in polyurethane foams, high impact polystyrenes, and textiles. The most commonly used PBDE is the decabrominated formulation (DecaBDE) with a worldwide demand of 56,000 metric tons in 2001. Recently, two PBDE flame retardants (PentaBDE and OctaBDE) were withdrawn from the market due to persistence and toxicity issues. DecaBDE is still in use but is undergoing further review with regard to its bioavailability, persistence, and possible degradation to more toxic brominated compounds. In a six-week feeding study with rats, we have investigated the potential bioconcentration, debromination, and persistence of DecaBDE. DecaBDE appeared to be minimally absorbed by rats from their food (4% of the dosed DecaBDE present in rats after 21 days of feeding); however, 90% of the dose was not recovered suggesting extensive uptake and metabolism by the rats. DecaBDE was debrominated to a small extent (1% of the dose) and these lower brominated compounds were generally more persistent than DecaBDE. Based on its retention in the whole rat carcass, DecaBDE was found to be more persistent than previously reported but still not as persistent as other PBDEs, such as the PentaBDE or OctaBDE.
Decabromodiphenyl ether (BDE-209) is the major component in the flame retardant formulation DecaBDE which is incorporated into numerous consumer goods ranging from upholsteries to electronics. Because of the high volume of DecaBDE produced, its presence in consumer products, and the finding of BDE-209 in the blood of exposed workers, questions about its bioavailability and persistence have arisen. To study the bioavailability, persistence, and possible debromination to lower brominated diphenyl ethers, we dosed rats with 300 ppb dietary DecaBDE for 21 days and measured tissue BDE levels during a 21 day withdrawal period. BDE-209, three nona-BDEs, and four octa-BDEs accumulated in the rats and distributed proportionately throughout the body. Only 5% of the total BDE-209 dose was present in the rats after 21 days of dosing, and 90% was not accounted for in the excreta or tissues suggesting extensive metabolism. A nona-BDE (BDE-207) and two octa-BDEs (BDE-201 and 197) appeared to form via meta-debromination(s) of BDE-209 to the extent of 1% of the total BDE-209 dose. The whole body half-lives tended to increase with decreasing bromination from BDE-209 to the octa-BDEs and ranged from 9 – 65 d. The two octa-BDEs, presumably forming from debromination, increased in the rats after 21 days of withdrawal.