Maternal transfer, distribution, and metabolism of BDE-47 and its related hydroxylated, methoxylated analogs in zebrafish (Danio rerio)

• Published in: Chemosphere (Oxford) 2015-02, Vol.120, p.31-36
• Main Authors: Wen, Quan, Liu, Hong-ling, Zhu, Yu-ting, Zheng, Xin-mei, Su, Guan-yong, Zhang, Xiao-wei, Yu, Hong-xia, Giesy, John P., Lam, Michael H.W.
• Format: Article
• Language: English
• Subjects: Adults; Animals; Anisoles - analysis; Anisoles - metabolism; Biotransformation; Body burden; Carcasses; Danio rerio; Eggs; Environmental Pollutants - analysis; Environmental Pollutants - metabolism; Exposure; Female; Females; Halogenated Diphenyl Ethers - analysis; Halogenated Diphenyl Ethers - metabolism; Hydroxylation; Inter-conversion; Liver; Liver - metabolism; Male; Maternal Exposure; Offspring; Oryzias latipes; Ovum - chemistry; Polybrominated Biphenyls - analysis; Polybrominated Biphenyls - metabolism; Precursors; Tandem Mass Spectrometry; Transformation; Transformations; Zebrafish - metabolism
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2014.05.050

[Display omitted] •Concentrations of all compounds in liver of male zebrafish were greater than those in females.•Maternal transfer of MeO-BDE-47 was greater than that of OH-BDEs.•MeO-BDE-47 was transformed to OH-BDE-47.•BDE-47 was not transformed into either MeO-PBDEs or OH-PBDEs. OH-PBDEs have been reported to be more potent than the postulated precursor PBDEs or corresponding MeO-PBDEs. However, there are contradictory reports for transformation of these compounds in organisms, particularly, for biotransformation of OH-PBDEs and MeO-PBDEs, only one study reported transformation of 6-OH-BDE-47 and 6-MeO-BDE-47 in Japanese medaka. In present study zebrafish (Danio rerio) were exposed to BDE-47, 6-OH-BDE-47, 6-MeO-BDE-47, 2′-OH-BDE-28 and 2′-MeO-BDE-28 in the diet for 20d. Concentrations of each exposed compound were measured in eggs collected on days 0, 5, 10, 15 or 20. After 20d exposure, concentrations of precursor and biotransformation products in liver and liver-free residual carcass were measured by use of GC–MS/MS. Total mass of the five compounds in bodies of adults were: 2′-MeO-BDE-28∼6-MeO-BDE-47>BDE-47>2′-OH-BDE-28>6-OH-BDE-47. MeO-PBDEs were also accumulated more into parental fish body than in liver, while OH-PBDEs accumulated in liver more than in liver-free residual carcass. Concentrations in liver of males were greater than those of females. This result suggests sex-related differences in accumulation. Ratios between concentration in eggs and liver (E/L) were: 2.9, 1.7, 0.8, 0.4 and 0.1 for 6-MeO-BDE-47, BDE-47, 6-OH-BDE-47, 2′-MeO-BDE-28 and 2′-OH-BDE-28, respectively. This result suggests transfer from adult females to eggs. BDE-47 was not transformed into OH-PBDEs or MeO-PBDEs. Inter-conversions of 6-OH-BDE-47 and 6-MeO-BDE-47, 2′-OH-BDE-28 and 2′-MeO-BDE-28 were observed, with metabolite/precursor concentration ratios for 6-OH-BDE-47, 6-MeO-BDE-47, 2′-OH-BDE-28 and 2′-MeO-BDE-28 being 3.8%, 14.6%, 2.9% and 76.0%, respectively. Congener-specific differences were observed in distributions between liver and carcass, maternal transfer and transformation. The two MeO-PBDEs were accumulated into adults, transferred to eggs, and were transformed to the structural similar OH-PBDEs, which might be more toxic. BDE-47 was accumulated into adults and transferred from females to eggs, but not transformed to MeO-PBDEs and/or OH-PBDEs. Accumulation of OH-PBDEs into adults as well as rates of transformation of OH-PBDEs to MeO-PBDEs were all several ord