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Exposure to hexabromocyclododecanes (HBCDs) via dust ingestion, but not diet, correlates with concentrations in human serum: preliminary results.

Roosens L, Abdallah MA, Harrad S, Neels H, Covaci A - Environ. Health Perspect. (2009)

Bottom Line: Dietary intakes of SigmaHBCDs 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 SigmaHBCDs measured in blood serum were < 0.5 to 11 ng/g lipid weight (lw) (average, 2.9 ng/g lw).Gamma-HBCD dominated in food, whereas alpha-HBCD dominated in dust and was the sole isomer in serum.

View Article: PubMed Central - PubMed

Affiliation: Toxicological Centre, Department of Pharmaceutical Sciences, University of Antwerp, Wilrijk, 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 (SigmaHBCDs) 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 alpha-, beta-, and gamma-HBCD in duplicate diets, dust, and serum were measured by liquid chromatography/tandem mass spectrometry.

Results: Dietary intakes of SigmaHBCDs 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 SigmaHBCDs measured in blood serum were < 0.5 to 11 ng/g lipid weight (lw) (average, 2.9 ng/g lw). Gamma-HBCD dominated in food, whereas alpha-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 (-)alpha-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 (-)alpha-HBCD enantiomer in humans appears to be due to in vivo enantioselective metabolism/excretion rather than ingestion of dust or diet.

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Average percentage distribution of individual HBCD isomers in food, dust, and serum.
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f1-ehp-117-1707: Average percentage distribution of individual HBCD isomers in food, dust, and serum.

Mentions: A diastereomeric shift toward α-HBCD is likely to occur in biotic samples because of preferential metabolism of β-HBCD and γ-HBCD by cytochrome P450 (Zegers et al. 2005). The presence of γ-HBCD in the dust and food samples of the present study and its complete absence in the corresponding serum samples (Figure 1) is consistent with in vivo transformation of γ-HBCD to α-HBCD, and with the observations of Weiss et al. (2006) that α-HBCD was the predominant isomer (97–99% of ∑HBCDs) in a pooled serum sample comprising blood from 53 individuals. Although α-HBCD dominated, we also detected small amounts (1–3%) of γ-HBCD. In contrast, some studies reported γ-HBCD to have a higher percentage of the total HBCDs in human tissues, such as adipose tissue (Johnson-Restrepo et al. 2008) and serum samples (Thomsen et al. 2007). Eljarrat et al. (2009) recently reported on the dominance of γ-HBCD in 24 of 30 Spanish breast milk samples, whereas α-HBCD was predominant in the remainder. Interestingly, the HBCD concentrations in the Spanish study are higher compared with similar studies (Antignac et al. 2008; Kakimoto et al. 2008; Polder et al. 2008), indicating a higher exposed population. An increase in the percentage of γ-HBCD has also been seen in occupationally exposed workers, with γ-HBCD making up to 40% of ∑HBCDs (Thomsen et al. 2007). Although the reasons for the different isomer profiles in human tissues from different studies are not yet clear, it is reasonable to hypothesize that they arise from a combination of differences in external exposures (e.g., α-HBCD predominated in both dust and diet of the present study) and interindividual variations in metabolism. More detailed studies are required to comprehend the cause(s) of the isomer profiles observed in humans.


Exposure to hexabromocyclododecanes (HBCDs) via dust ingestion, but not diet, correlates with concentrations in human serum: preliminary results.

Roosens L, Abdallah MA, Harrad S, Neels H, Covaci A - Environ. Health Perspect. (2009)

Average percentage distribution of individual HBCD isomers in food, dust, and serum.
© Copyright Policy - public-domain
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2801203&req=5

f1-ehp-117-1707: Average percentage distribution of individual HBCD isomers in food, dust, and serum.
Mentions: A diastereomeric shift toward α-HBCD is likely to occur in biotic samples because of preferential metabolism of β-HBCD and γ-HBCD by cytochrome P450 (Zegers et al. 2005). The presence of γ-HBCD in the dust and food samples of the present study and its complete absence in the corresponding serum samples (Figure 1) is consistent with in vivo transformation of γ-HBCD to α-HBCD, and with the observations of Weiss et al. (2006) that α-HBCD was the predominant isomer (97–99% of ∑HBCDs) in a pooled serum sample comprising blood from 53 individuals. Although α-HBCD dominated, we also detected small amounts (1–3%) of γ-HBCD. In contrast, some studies reported γ-HBCD to have a higher percentage of the total HBCDs in human tissues, such as adipose tissue (Johnson-Restrepo et al. 2008) and serum samples (Thomsen et al. 2007). Eljarrat et al. (2009) recently reported on the dominance of γ-HBCD in 24 of 30 Spanish breast milk samples, whereas α-HBCD was predominant in the remainder. Interestingly, the HBCD concentrations in the Spanish study are higher compared with similar studies (Antignac et al. 2008; Kakimoto et al. 2008; Polder et al. 2008), indicating a higher exposed population. An increase in the percentage of γ-HBCD has also been seen in occupationally exposed workers, with γ-HBCD making up to 40% of ∑HBCDs (Thomsen et al. 2007). Although the reasons for the different isomer profiles in human tissues from different studies are not yet clear, it is reasonable to hypothesize that they arise from a combination of differences in external exposures (e.g., α-HBCD predominated in both dust and diet of the present study) and interindividual variations in metabolism. More detailed studies are required to comprehend the cause(s) of the isomer profiles observed in humans.

Bottom Line: Dietary intakes of SigmaHBCDs 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 SigmaHBCDs measured in blood serum were < 0.5 to 11 ng/g lipid weight (lw) (average, 2.9 ng/g lw).Gamma-HBCD dominated in food, whereas alpha-HBCD dominated in dust and was the sole isomer in serum.

View Article: PubMed Central - PubMed

Affiliation: Toxicological Centre, Department of Pharmaceutical Sciences, University of Antwerp, Wilrijk, 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 (SigmaHBCDs) 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 alpha-, beta-, and gamma-HBCD in duplicate diets, dust, and serum were measured by liquid chromatography/tandem mass spectrometry.

Results: Dietary intakes of SigmaHBCDs 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 SigmaHBCDs measured in blood serum were < 0.5 to 11 ng/g lipid weight (lw) (average, 2.9 ng/g lw). Gamma-HBCD dominated in food, whereas alpha-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 (-)alpha-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 (-)alpha-HBCD enantiomer in humans appears to be due to in vivo enantioselective metabolism/excretion rather than ingestion of dust or diet.

Show MeSH
Related in: MedlinePlus