PBDE developmental effects on embryonic zebrafish.

Polybrominated diphenyl ethers (PBDEs) have become ubiquitous environmental contaminants with potential for bioaccumulation and maternal-fetal transfer that has led to regulatory bans and/or phasing out of several technical mixtures of PBDEs. In the present study, six PBDE congeners (BDE 28, BDE 47, BDE 99, BDE 100, BDE 153, BDE 183) were evaluated for developmental effects on embryonic zebrafish. These congeners were chosen because they are environmentally relevant and cover a wide range of physical-chemical properties. Alterations in behavior, physical malformations, and mortality were scored daily until 168 h postfertilization (hpf). A concentration-dependent increase in spontaneous movement indicated an early onset of behavioral responses to PBDE exposures. Spontaneous movement was affected the most by BDE 47 and BDE 28, whereas BDE 183 did not alter behavior at any concentration tested. Swimming rates were significantly increased by BDE 28 at 96 and 120 hpf, but decreased swimming activity at 168 hpf. Additionally, BDE 47 significantly decreased the swimming rate at 168 hpf. Other endpoints included malformations and mortality. Congeners with fewer bromines (BDE 28, 47, 99, and 100) also induced a curved body axis starting around 120 hpf, which was followed by mortality. BDEs 153 and 183, however, did not elicit these adverse effects. A relationship was found between log K(OW) and median lethal concentration (LC50) and median effective concentration (EC50). Structure-activity relationships in this study suggest that PBDE acute toxicity results from a receptor-mediated effect and further studies are necessary to determine these pathways.