Bioaccumulation and Biotransformation of BDE‐47 Using Zebrafish Eleutheroembryos (Danio rerio)

Abstract

Polybrominated diphenyl ethers (PBDEs) are well-known endocrine disrupting chemicals (EDCs) identified as organic persistent pollutant (POPs). Their metabolites OH-BDE and MeO-BDE have been reported to be potentially more toxic than the postulated precursor PBDEs. BDE-47 is the one of the most predominant congener of PBDEs in the environment by its high presence on the industrially used mixtures. In this study, the bioaccumulation and biotransformation of BDE-47 into its major metabolites is evaluated using zebrafish (Danio rerio) eleutheroembryos adapting a previously developed alternative method to bioconcentration official guideline OECD 305, which reduces dramatically the animal suffering, time and cost. For the simultaneous determination of BDE-47 and its metabolites in larvae and exposure medium and considering the polarity difference of the analytes and the small sample size, the development of an validated analytical method is a clue step to ensure quality results. In this study, an ultrasound-assisted extraction followed by a SPE dispersive clean-up step and GC-MS-μECD with a previous derivatization process was optimized and validated. , Bioconcentration factors (BCF) were calculated using first order one-compartment toxicokinetic model. The profiles found show rapid absorption in the first hours of larval development and great bioaccumulative capacity, finding BCF of 6631 and 44210 at nominal concentrations of 10 and 1 μg·L-1, respectively. Metabolization studies show increasing concentrations of the metabolites BDE-28, 2'-OH-BDE-28 and 5-MeO-BDE-47 throughout the exposure time. The results obtained show the feasibility of the method for bioaccumulation and opens the possibility of metabolic studies with zebrafish eleutheroembryos, which is a very underdeveloped field without official testing or regulation.

Polybrominated diphenyl ethers (PBDEs) are well-known endocrine disrupting chemicals (EDCs) identified as organic persistent pollutant (POPs). Their metabolites OH-BDE and MeO-BDE have been reported to be potentially more toxic than the postulated precursor PBDEs. BDE-47 is the one of the most predominant congener of PBDEs in the environment by its high presence on the industrially used mixtures. In this study, the bioaccumulation and biotransformation of BDE-47 into its major metabolites is evaluated using zebrafish (Danio rerio) eleutheroembryos adapting a previously developed alternative method to bioconcentration official guideline OECD 305, which reduces dramatically the animal suffering, time and cost. For the simultaneous determination of BDE-47 and its metabolites in larvae and exposure medium and considering the polarity difference of the analytes and the small sample size, the development of an validated analytical method is a clue step to ensure quality results. In this study, an ultrasound-assisted extraction followed by a SPE dispersive clean-up step and GC-MS-μECD with a previous derivatization process was optimized and validated. , Bioconcentration factors (BCF) were calculated using first order one-compartment toxicokinetic model. The profiles found show rapid absorption in the first hours of larval development and great bioaccumulative capacity, finding BCF of 6631 and 44210 at nominal concentrations of 10 and 1 μg·L-1, respectively. Metabolization studies show increasing concentrations of the metabolites BDE-28, 2'-OH-BDE-28 and 5-MeO-BDE-47 throughout the exposure time. The results obtained show the feasibility of the method for bioaccumulation and opens the possibility of metabolic studies with zebrafish eleutheroembryos, which is a very underdeveloped field without official testing or regulation.