文摘
The toxicokinetics of 2,2,4,4-tetrabromodiphenyl ether(PBDE-47) was studied in the Japanese Medaka (Oryziaslatipes) after a single oral exposure followed by terminationat specific time points. The effects of repeated oralexposure to PBDE-47 on reproductive performance wasassessed using a pair breeding experimental design withfathead minnows (Pimephales promelas) given daily PBDE-47 exposures for 25 days, during which fecundity wasmeasured as an indicator of reproductive performance.Medaka and fathead minnows were orally exposed to PBDE-47 by bioencapsulation in brine shrimp, Artemia sp. Inthe medaka studies, measurable levels of PBDE-47 weredetected in the carcass within 0.25 h with peak levels occurringat 8 h. The body levels of PBDE-47 slowly declined andwere still 25% of peak levels at 624 h after dosing. Assimilationof the bioencapsulated dose was at least 80% and maywell approach 100%. The PBDE-47 concentration-time profilewas fitted to a one-compartment clearance-volumetoxicokinetic model and the model-predicted value forelimination half-life was determined to be 281 h and the first-order absorption rate constant was Ka = 0.26 hr-1. Inthe fathead minnow study, egg laying in the PBDE-treatedbreeding pairs stopped after 10 days. The conditionfactor of PBDE-treated males was significantly reduced(P <0.011) compared with control males, whereas nosignificant difference was observed in females. Histologicalexamination revealed a greater than 50% reduction inmature sperm in PBDE-47 exposed minnows compared tocontrols. Collectively, these results suggest PBDE-47 isselectively toxic to sexually mature male fathead minnows.