Thyroid disruption by technical decabromodiphenyl ether (DE-83R)at low concentrations in Xenopus laevis
Xiaofei Qin , Xijuan Xia , Zhongzhi Yang , Shishuai Yan , Yaxian Zhao , Rongguo Wei , Yan Li , Mi Tian , Xingru Zhao , Zhanfen Qin , Xiaobai Xu
DOI:
Received July 15, 2009,Revised August 31, 2009, Accepted , Available online
Volume 22,2010,Pages 744-751
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Decabromodiphenyl ether (decaBDE), as a flame retardant, is widely produced and used. To study the thyroid disruption by technical
decaBDE at low concentrations, Xenopus laevis tadpoles were exposed to technical decaBDE mixture DE-83R (1–1000 ng/L) in
water from stage 46/47 (free swimming larvae, system of Nieuwkoop and Faber) to stage 62. DE-83R at concentration of 1000 ng/L
significantly delayed the time to metamorphosis (presented by forelimb emergence, FLE). Histological examination showed that DE-
83R at all tested concentrations caused histological alterations – multilayer follicular epithelial cell and markedly increased follicle size
accompanied by partial colloid depletion and increase in the peripheral colloid vacuolation, in thyroid glands. All tested concentrations
of DE-83R also induced a down-regulation of thyroid receptor mRNA expression. These results demonstrated that technical decaBDE
disrupted the thyroid system in X. laevis tadpoles. Analysis of polybrominated diphenyl ethers (PBDEs) (sum of 39 congeners) in X.
laevis indicated that mean concentrations of total PBDEs in X. laevis exposed to 1, 10, 100, 1000 ng/L were 11.0, 128.1, 412.1, 1400.2
ng/g wet weight, respectively. Considering that PBDEs burden of X. laevis tadpoles was close to PBDEs levels in amphibians as reported
in previous studies, our study has raised new concerns for thyroid disruption in amphibians of technical decaBDE at environmentally
relevant concentrations.
