Submitted to: Meeting Abstract
Publication Type: Abstract only
Publication Acceptance Date: 5/17/2012
Publication Date: 8/19/2012
Citation: Hakk, H., Huwe, J.K. 2012. Comparative metabolism of [14C]alpha-, beta-, and gamma-hexabromocyclododecane (HBCD) in rats. 244th American Chemical Society Meeting & Exposition, August 19-23, 2012, Philadelphia, PA. Abstract 26. Interpretive Summary:
Technical Abstract: Hexabromocyclododecane (HBCD) is a persistent flame retardant manufactured as a mixture of alpha-, beta-, and gamma-stereoisomers. HBCD is a candidate to be included on the international list of persistent organic pollutants (POPs), which would have important implications to trade of American food products. One of the isomers, '-HBCD dominates the commercial product, while a-HBCD dominates biotic residues. Why this occurs could be due to differential metabolism, intestinal absorption, exposure or interconversion of the isomers. Elucidation of the pathway of HBCD isomer pattern changes from commercial product to biological tissues will be important to agriculture from a prevention or remediation standpoint. The goal of this research was to evaluate the fate of individual HBCD stereoisomers in rats as a model mammal. Each isomer was readily eliminated in feces and urine, with elimination proceeding beta > gamma > alpha. The fatty tissues contained the greatest concentration of residues, and each isomer was detected in the brain, which may explain the neurotoxicity of HBCD. Each HBCD isomer was metabolized to a different extent and by different pathways as measured in urine, feces and liver. The conclusion was that persistence of HBCD stereoisomers was generally low and was isomer specific. Differences in isomer fate were due to metabolism and interconversion, not differential intestinal absorption or exposure. These data suggest that mammals can metabolize and eliminate the majority of HBCD consumed, but that the toxicity of low residual levels needs to still be elucidated, and acceptable tissue levels established for trade purposes.