Bioaccumulation and lack of toxicity of octachlorodibenzofuran (OCDF) and octachlorodibenzo-p-dioxin (OCDD) to early-life stages of zebra fish (Brachydanio rerio)

Previous studies with octachlorodibenzo-p-dioxin (OCDD) and octachlorodibenzofuran (OCDF) in juvenile or adult fish exposed via water revealed no toxicity, despite significant bioaccumulation. With 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD), the fish early-life stage study has been shown to be the most sensitive test system. Therefore, the effects of OCDD and OCDF on the early-life stages of zebra fish (Brachydanio rerio) were determined during a flow-through test based on a column generator method. No statistically significant effect of OCDD and OCDF on the survival and hatching time of the eggs was found. Furthermore, no effects on survival, weight, general appearance or behaviour of the larvae were observed at the end of the exposure period of 32 days. GC-MS analysis of test solution samples revealed geometric mean measured concentrations of 32 (OCDD) and 34 ng/l (OCDF), respectively. Concentrations in surviving larvae at the end of the study were 61 (OCDD) and 94 (OCDF) μg/kg, respectively. These concentrations in zebra fish larvae were several orders of magnitude higher than concentrations in fish collected from the wild. In a review of the available laboratory fish experiments, we found a lack of biomagnification of OCDD and OCDF. We do not expect to find adverse effects of these compounds on the aquatic environment.