Bioaccumulation, maternal transfer and effects of dietary 2,2′,4,4′-tetrabromodiphenyl ether (BDE-47) exposure on medaka fish (Oryzias latipes) offspring

A previous study conducted in our laboratory with growing medaka (Oryzias latipes) showed the capacity of BDE-47 (10-1000 ng/g) to bioaccumulate during a 40-day oral exposure. However, the results did not provide evidence for effects during or after the exposure period. In this study, breeding medakas were fed a diet for 40 days that contained 1000 ng of BDE-47/g. At predefined time points, females (time points 10, 20, 30 and 40), males (time points 30 and 40) and pools of laid eggs (time points 10, 20, 30 and 40) were sampled and collected for: 1) the BDE-47 quantitative analysis in adults in the <24-h-old post-fertilization (hpf) embryos, and in the <24-h-old post-hatch (hph) eleutheroembryos; 2) the evaluation of fecundity, fertility and hatching. Additional pools of embryos collected at time point 40 were evaluated for: 1) the active swimming behavior of the 48 hph offspring in the eleutheroembryonic stage; 2) the BDE-47 quantification in the 240 hph resultant larvae. BDE-47 accumulated in parents rapidly, and concentrations remained constant at higher levels in males (values within the 50-60 ng/g wet weight −w.w.- range) compared with females (70 ng/g w.w. range). The BDE-47 concentrations detected in embryos and eleutheroembryos ranged from 200 to 500 ng/g w.w. for time points 10-40. Reproductive capacity, hatching and ensuing swim bladder inflation were not affected by parental BDE-47 dietary exposure, nor was the active swimming behavior in eleutheroembryos. The BDE-47 concentration in the 240 hph larvae lowered to levels close to those detected in parents. Despite the efficient BDE-47 maternal transfer, these results offered no evidence for BDE-47 effects on fish reproduction or in the early life stages of offspring.