Effects of life cycle exposure to dietary 2,2', 4,4'-tetrabromodiphenyl ether (BDE-47) on medaka fish (Oryzias latipes)

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Previous studies conducted in our laboratory, which resorted to 40-day oral exposures to BDE-47 in specific developmental windows of medaka (Oryzias latipes) did not evidence effects on growing or breeding periods. In this new study, full life cycle (i.e. 140-day) dietary exposure to 1000 ng of BDE-47/g was performed with medaka to evaluate effects on growth and reproduction (i.e. fecundity, fertility, hatchability), and to analyze the bioacumulated BDE-47 in and transferred to offspring. No significant effects were observed for the biometric analyses during the growth and maturation periods and no biased sex ratios were found. Reproductive capacity was not affected by the presence of BDE-47 in diet. There was no evidence for apparent effects from parental exposure during embryo and eleutheroembryo development. The analytical results revealed steady BDE-47 bioaccumulation during the growing period, which remained in the reproductive phase in males, and a decreasing tendency was noted in females. These lowering BDE-47 levels in females coincided with the detected BDE-47 levels offloaded in embryos. In the 10-day-old post-hatch larvae, the BDE-47 concentrations dropped to comparatively lower values than the concentrations detected in parents. This finding suggests an efficient metabolic process in the eleutheroembryonic and post-eleutheroembryonic phases. Our 140-day dietary approach found no BDE-47 effects on medaka growth and reproduction, or in early progeny stages despite effective bioaccumulation and maternal transfer.

This work has been supported by Spanish Government Grant RTI2018-096046-B-C21 funded by the MCIN/AEI/ 10.13039/501100011033 and the ERDF. All the experimental procedures were previously approved by the INIA Institutional Animal Care and Use Committee in accordance with the principles of the Declaration of Helsinki and European Directive 86/609/EEC. The contents presented in this work are solely the authors' responsibility and do not necessarily represent the official views of the supporting Governmental Institutions.

Peer reviewed