Evaluating Toxic Effects Of PCDD/F By Using Fish Primary Cell Culture

Polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/F) have become the focus of attention all over the world because of their strong toxicity and persistence in environment. Due to the high cost of chemical analysis for PCDD/F and the in vitro results could not realisticly reflect toxicity of pollutants in environment, the demand for the toxicity test and the risk assessment has stimulated the development of bioassays. At present study, PCDD/Fs were used as model compounds of endocrine disruptor and the induction of ethoxyresorufin-O-deethylase (EROD) was used as biomarker to investigate their toxic effects by using fish primary hepatocyte culture. The conclusions can be drawn from this study as follows:1. Based on the work of predecessors, the method of primary hepatocyte culture of grass carp was established. The key advantage of this method is: easily employed in risk assessment with a short culture period.2. A good dose-response relationship between the EROD activity and 2,3,7,8-tetrachlorinated dibenzo-p-dioxin (TCDD) concentration was obtained in grass carp primary hepatocyte culture. When the primary hepatocytes were exposed to low-dose TCDD, the best exposing period was 4 days and the best interacting time for EROD measurement was 30 minutes. The EC50 of environmental samples measured under this condition may have a good relevancy to predict the relative toxic potency of dioxin-like pollutants.3. At the same time, a good dose-response relationship between the EROD activity and TCDD concentration was also obtained in vitro cell culture (H4IIE). H4IIE was more sensitive to TCDD and the EC50 was lower about 10 times thanthat in primary cell culture in this study.4. When TEQ values derived from both in vitro and primary culture bioassays were compared with the results from chemical analysis respectively, the comparison results demonstrated that they were well correlated to the results from chemical analysis. The TEQs from in vitro bioassay were more closed to the results from chemical analysis. The difference between the results from both bioassays was very conspicuous. Because of intact characteristics of primary cells, the TEQs from primary cell culture can more realisticly reflect the biotransformation process and toxic effects of pollutants in environment.