Temporal changes and stereoisomeric compositions of 1,2,5,6,9,10-hexabromocyclododecane and 1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane in marine mammals from the South China Sea

Yuefei RUAN, Chung Wah James LAM, Xiaohua ZHANG, Paul K. S. LAM

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Abstract

Stereoisomeric compositions of 1,2,5,6,9,10-hexabromocyclododecane (HBCD) and 1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane (TBECH) were investigated in the blubber of two species of marine mammals, finless porpoises (Neophocaena phocaenoides) and Indo-Pacific humpback dolphins (Sousa chinensis), from the South China Sea between 2005 and 2015. The concentrations of ΣHBCD in samples of porpoise (n = 59) and dolphin (n = 32) ranged from 97.2 to 6,260 ng/g lipid weight (lw) and from 447 to 45,800 ng/g lw, respectively, while those of ΣTBECH were both roughly 2 orders of magnitude lower. A significant increasing trend of ΣHBCD was found in dolphin blubber over the past decade. The diastereomeric profiles exhibited an absolute predominance of α-HBCD (mostly >90%), while the proportions of four TBECH diastereomers in the samples appeared similar. A preferential enrichment of the (−)-enantiomers of α-, β-, and γ-HBCD was found in most blubber samples. Interestingly, the body lengths of porpoises showed a significant negative correlation with the enantiomer fractions of α-HBCD. Significant racemic deviations were also observed for α-, γ-, and δ-TBECH enantiomeric pairs. This is the first report of the presence of TBECH enantiomers in the environment. The estimated hazard quotient indicates that there is a potential risk to dolphins due to HBCD exposure. Copyright © 2018 American Chemical Society.
Original languageEnglish
Pages (from-to)2517-2526
JournalEnvironmental Science & Technology
Volume52
Issue number5
DOIs
Publication statusPublished - 2018

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Mammals
marine mammal
dolphin
porpoise
Chemical analysis
Enantiomers
lipid
Lipids
hazard
sea
1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane
hexabromocyclododecane
Hazards

Citation

Ruan, Y., Lam, J. C. W., Zhang, X., & Lam, P. K. S. (2018). Temporal changes and stereoisomeric compositions of 1,2,5,6,9,10-hexabromocyclododecane and 1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane in marine mammals from the South China Sea. Environmental Science & Technology, 52(5), 2517-2526. doi: 10.1021/acs.est.7b05387