Alteration of Diastereoisomeric and Enantiomeric Profiles of Hexabromocyclododecanes (HBCDs) in Adult Chicken Tissues, Eggs, and Hatchling Chickens

Zheng, Xiaobo; Qiao, Lin; Sun, Runxia; Luo, Xiao-Jun; Zheng, Jing; Xie, Qi; Sun, Yuxin; Xian, Bi

doi:10.1021/acs.est.6b06557

Cited by 25 publications

(7 citation statements)

References 38 publications

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“…The α-/γ-isomer concentration ratios in fish from the two sampling sites from Lake Superior were 15.1 and 14.5, and for all the other sites the α-/γ-isomer concentration ratios were lower than 10. It has been shown that α-HBCDD predominates in ∑HBCDD concentrations in biotic samples, whereas γ-HBCDD is the predominant isomer in technical HBCDD mixtures and abiotic samples. − , The underlying reasons leading to a given HBCDD isomer pattern in an abiotic or biotic sample can be due to, e.g., differential chemical-specific absorption and elimination, metabolism, and isomerization among three HBCDD isomers in biota. ,, Given the increasing percentage of α-HBCDD with time, some researchers have suggested that concentration ratios of HBCDD isomers can partly reflect recent inputs of technical HBCDD mixtures into the environment. , Interestingly, the lowest α-/γ-isomer concentration ratio (6.3, Figure ) was detected in fish from Lac Memphrémagog, and this location is near an area with historic manufacturing use of HBCDD.…”

Section: Resultsmentioning

confidence: 99%

Isomer-Specific Hexabromocyclododecane (HBCDD) Levels in Top Predator Fish from Across Canada and 36-Year Temporal Trends in Lake Ontario

McGoldrick

Clark

et al. 2018

Environ. Sci. Technol.

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Hexabromocyclododecane (HBCDD) is a high concern environmental pollutant due to its persistent, bioaccumulative, and toxic properties. The spatial distribution of HBCDD was investigated in top predator fish (lake trout, walleye, or brook trout) collected in 2013 ( n = 165) from 19 sampling sites and in 2015 ( n = 145) from 20 sites across Canada. HBCDD was measurable in at least one sample at each sampling site regardless of sampling year with the exception of walleye from the south basin of Lake Winnipeg (2013). Sampling sites in or near the Laurentian Great Lakes had greater ΣHBCDD concentrations compared to locations to the west or east. The greatest mean ΣHBCDD concentration was 72.6 ng/g lw in fish from Lake Huron-Goderich (2015). Regardless of the sampling sites, α-HBCDD was the dominant congener followed by γ-HBCDD, whereas β-HBCDD was barely detectable. In fish from the same waterbody there were comparable α/γ isomer concentration ratios. The greatest ratio was 20.8 in fish from Lake Ontario, whereas the lowest ratio was 6.3 for fish from Lac Memphrémagog (Québec) likely related to more recent emissions of a technical HBCDD mixture. Temporal trends of HBCDD in lake trout from Lake Ontario showed a significant decreasing trend for γ-HBCDD with a half-life estimate of 10 years over a 36-year period (1979-2015), and for α-HBCDD with a half-life of 11 years over the years of 2008 to 2015. The proportion of α-HBCDD to ΣHBCDD increased significantly during 1979 to 2015. The present study provided novel information on the isomer-specific HBCDDs in Canada freshwater fish.

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Section: Resultsmentioning

confidence: 99%

Isomer-Specific Hexabromocyclododecane (HBCDD) Levels in Top Predator Fish from Across Canada and 36-Year Temporal Trends in Lake Ontario

McGoldrick

Clark

et al. 2018

Environ. Sci. Technol.

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“…Enantiomeric selectivity of HBCD played key role in the toxicity and fate of HBCD stereoisomers in the environment. There is strong evidence that the environmental fates of HBCD are enantioselective ( Zhang et al, 2011 ; Zheng et al, 2017 ), while enantiomeric analysis has received relatively little attention in the literature on anaerobic degradation of HBCD. In this study, the occurrences of three pairs of enantiomers in the technical HBCD mixture, i.e., (±)α-, (±)β-, and (±)γ-HBCD, were confirmed.…”

Section: Resultsmentioning

confidence: 99%

“…Different physiochemical properties (e.g., polarity, water solubility, and dipole moment) of these HBCD stereoisomers may lead to substantial differences in their toxicity, metabolism, and environmental fate ( Hakk et al, 2012 ). Indeed, there is increasing evidence for the diastereoisomer- and/or enantiomer-specific distribution and accumulation in various environmental media ( Yu et al, 2008 ; Haukås et al, 2009 ; Gao et al, 2011 ; Zhang et al, 2011 ; Wu et al, 2014 ), biota ( Janák et al, 2005 ; Zheng et al, 2017 ), and even in human body ( Shi et al, 2009 ).…”

Section: Introductionmentioning

confidence: 99%

Diastereoisomer-Specific Biotransformation of Hexabromocyclododecanes by a Mixed Culture Containing Dehalococcoides mccartyi Strain 195

Zhong

Wang

et al. 2018

Front. Microbiol.

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Hexabromocyclododecane (HBCD) stereoisomers may exhibit substantial differences in physicochemical, biological, and toxicological properties. However, there remains a lack of knowledge about stereoisomer-specific toxicity, metabolism, and environmental fate of HBCD. In this study, the biotransformation of (±)α-, (±)β-, and (±)γ-HBCD contained in technical HBCD by a mixed culture containing the organohalide-respiring bacterium Dehalococcoides mccartyi strain 195 was investigated. Results showed that the mixed culture was able to efficiently biotransform the technical HBCD mixture, with 75% of the initial HBCD (∼12 μM) in the growth medium being removed within 42 days. Based on the metabolites analysis, HBCD might be sequentially debrominated via dibromo elimination reaction to form tetrabromocyclododecene, dibromocyclododecadiene, and 1,5,9-cyclododecatriene. The biotransformation of the technical HBCD was likely diastereoisomer-specific. The transformation rates of α-, β-, and γ-HBCD were in the following order: α-HBCD > β-HBCD > γ-HBCD. The enantiomer fractions of (±)α-, (±)β-, and (±)γ-HBCD were maintained at about 0.5 during the 28 days of incubation, indicating a lack of enantioselective biotransformation of these diastereoisomers. Additionally, the amendment of another halogenated substrate tetrachloroethene (PCE), which supports the growth of strain 195, had a negligible impact on the transformation patterns of HBCD diastereoisomers and enantiomers. This study provided new insights into the stereoisomer-specific transformation patterns of HBCD by anaerobic microbes and has important implications for microbial remediation of anoxic environments contaminated by HBCD using the mixed culture containing Dehalococcoides.

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“…The calculated bioaccumulation factors were 5.2, 3.6 and 9.2 in eggs, liver and abdominal fat, respectively. Zheng et al (2017) measured HBCDDs in diet sources and in chicken tissues in adult (n = 12) and hatchling chicken (n = 9). In feed samples, the highest HBCDD concentration measured was 0.69 ng/g dw while the highest concentration in soil was 28.8 ng/g dw.…”

Section: Transfer Of Hbcdds From Feed To Food-producing Animalsmentioning

confidence: 99%

Update of the risk assessment of hexabromocyclododecanes (HBCDDs) in food

Schrenk

Bignami

Bodin³

et al. 2021

EFS2

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The European Commission asked EFSA to update its 2011 risk assessment on hexabromocyclododecanes ( HBCDD s) in food. HBCDD s, predominantly mixtures of the stereoisomers α‐, β‐ and γ‐ HBCDD , were widely used additive flame retardants. Concern has been raised because of the occurrence of HBCDD s in the environment, food and in humans. Main targets for toxicity are neurodevelopment, the liver, thyroid hormone homeostasis and the reproductive and immune systems. The CONTAM Panel concluded that the neurodevelopmental effects on behaviour in mice can be considered the critical effects. Based on effects on spontaneous behaviour in mice, the Panel identified a lowest observed adverse effect level ( LOAEL ) of 0.9 mg/kg body weight (bw) as the Reference Point, corresponding to a body burden of 0.75 mg/kg bw. The chronic intake that would lead to the same body burden in humans was calculated to be 2.35 μg/kg bw per day. The derivation of a health‐based guidance value ( HBGV ) was not considered appropriate. Instead, the margin of exposure ( MOE ) approach was applied to assess possible health concerns. Over 6,000 analytical results for HBCDD s in food were used to estimate the exposure across dietary surveys and age groups of the European population. The most important contributors to the chronic dietary LB exposure to HBCDD s were fish meat, eggs, livestock meat and poultry. The CONTAM Panel concluded that the resulting MOE values support the conclusion that current dietary exposure to HBCDD s across European countries does not raise a health concern. An exception is breastfed infants with high milk consumption, for which the lowest MOE values may raise a health concern.

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Alteration of Diastereoisomeric and Enantiomeric Profiles of Hexabromocyclododecanes (HBCDs) in Adult Chicken Tissues, Eggs, and Hatchling Chickens

Cited by 25 publications

References 38 publications

Isomer-Specific Hexabromocyclododecane (HBCDD) Levels in Top Predator Fish from Across Canada and 36-Year Temporal Trends in Lake Ontario

Isomer-Specific Hexabromocyclododecane (HBCDD) Levels in Top Predator Fish from Across Canada and 36-Year Temporal Trends in Lake Ontario

Diastereoisomer-Specific Biotransformation of Hexabromocyclododecanes by a Mixed Culture Containing Dehalococcoides mccartyi Strain 195

Update of the risk assessment of hexabromocyclododecanes (HBCDDs) in food

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