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Laurence Roosens,¹ Mohamed Abou-Elwafa Abdallah,^2,3 Stuart Harrad,² Hugo Neels,¹ and Adrian Covaci^1,4

¹Toxicological Centre, Department of Pharmaceutical Sciences, University of Antwerp, Wilrijk, Belgium; ²Division of Environmental Health and Risk Management, School of Geography, Earth, and Environmental Sciences, University of Birmingham, Birmingham, United Kingdom; ³Department of Analytical Chemistry, Faculty of Pharmacy, Assiut University, Assiut, Egypt; ⁴Laboratory for Ecophysiology, Biochemistry, and Toxicology, Department of Biology, University of Antwerp, Antwerp, Belgium

Abstract
Background: Hexabromocyclododecane (HBCD) is a high-production-volume chemical used as flame retardant in polystyrene insulation and textiles. Because it is not chemically bound to the polymer, HBCD can migrate into the environment, contaminating indoor dust and foodstuff.

Objectives: We examined for the first time the relationship between combined exposure to three HBCD isomers (ΣHBCDs) via ingestion of food (duplicate diets) and indoor dust and HBCD concentrations in serum for 16 Belgian adults (20–25 years of age) . We also determined the chiral signatures of HBCDs to advance understanding of source-to-human enantioselective degradation and/or metabolism.

Methods: Concentrations and chiral signatures of α-, β-, and γ-HBCD in duplicate diets, dust, and serum were measured by liquid chromatography/tandem mass spectrometry.

Results: Dietary intakes of ΣHBCDs were 1.2–20 ng/day (average, 7.2 ng/day) , whereas those estimated under average (20 mg dust/day) and high (50 mg dust/day) dust ingestion scenarios were 1.1–15 ng/day (average intake, 3.2 ng/day) and 2.8–38 ng/day (average intake, 8.0 ng/day) , respectively. Concentrations of ΣHBCDs measured in blood serum were < 0.5 to 11 ng/g lipid weight (lw) (average, 2.9 ng/g lw) . γ-HBCD dominated in food, whereas α-HBCD dominated in dust and was the sole isomer in serum. Although exposure via dust ingestion correlated significantly (p < 0.01) with concentrations in serum, no such correlation was evident with dietary exposure (p > 0.1) . Although no enantioselective enrichment was detected in either dust or diet, substantial enrichment of (–) α-HBCD was observed in serum.

Conclusions: Serum concentrations of HBCDs were correlated with the exposure via dust, but not via dietary ingestion. The enrichment of the (–) α-HBCD enantiomer in humans appears to be due to in vivo enantioselective metabolism/excretion rather than ingestion of dust or diet.

Key words: Belgium, blood serum, duplicate diets, dust, enantiomers, exposure assessment, HBCDs, humans, intake. Environ Health Perspect 117:1707–1712 (2009) . doi:10.1289/ehp.0900869 available via http://dx.doi.org/ [Online 13 July 2009]

Address correspondence to A. Covaci, Toxicological Centre, Department of Pharmaceutical Sciences, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk, Belgium. Telephone: 32-3-265 2498. Fax: 32-3-265 2722. E-mail: adrian.covaci@ua.ac.be

Supplemental Material is available online (doi:10.1289/ehp.0900869.S1 via http://dx.doi.org/) .

We gratefully acknowledge support from a postdoctoral fellowship from the Research Scientific Foundation of Flanders (A.C.) and a studentship from the Egyptian government and Egyptian Ministry of Higher Education (M.A.-E.A) .

The authors declare they have no competing financial interests.

Received 3 April 2009 ; accepted 13 July 2009.