Acute And Chronic Toxicity Of Tetrabromobisphenol A To Three Aquatic Species Under Different PH Conditions

Tetrabromobisphenol A (TBBPA) is a well-known and used most brominated flame retardant, including epoxy resin printed circuit board, fiber, papermaking, plastic and so on. It has been detected in the different environment, such as water, sediment, air, organism even human body. So far, its toxicological researches are mainly about its acute toxicity, morphology toxicity, hepatotoxicity, endocrine disrupting effects, nephrotoxicity and immunotoxicity. TBBPA has low water solubility and its solubility is largely depended on pH. Now, there is little information about the acute and chronic toxicity of TBBPA to different aquatic organisms in the presence or absence of co-solvents under different pH conditions.Based on the above backgrounds, some research works were conducted on TBBPA. Research contents and conclusion were summarized as following:1) The tests for the acute toxicity of TBBPA to D. magna and Limnodrilus hoffmeisteri (L. hoffmeisteri) were carried out according to the National Standard Method of China (water quality-determination of the acute toxicity of substances to Daphnia (D. magna straus) GB/T 13266-1991). The results showed that as for D. magna, the toxicity of TBBPA dissolved by DMSO (TBBPA-D) is higher than TBBPA and the toxicity decreased with increasing pH.Additionally, linear relationships between the EC50 values of TBBPA and TBBPA-D and pH were identified. In general, the EC50 values increased with increasing pH, and the EC50 values of TBBPA were higher than those of TBBPA-D. However, the differences between the EC50 values of TBBPA and TBBPA-D for L. hoffmeisteri were smaller than those for D. magna. Similar to the results of the toxicity study in D. magna, TBBPA and TBBPA-D exhibited the most acute toxic effects at pH 6.0 in L. hoffmeisteri. Additionally, linear relationships between the EC50 values of TBBPA and TBBPA-D and pH were identified. So it can be concluded that lower pH and DMSO can enhance the acute toxicity of TBBPA to D. magna and L. hoffmeisteri. Besides, there are synergistic effects between TBBPA and DMSO.2) In this paper, four biomarkers, including superoxide dismutase (SOD), catalase (CAT), glutathione-S-transferase (GST) and glutathione (GSH), were used to discuss the oxidative stress caused by TBBPA in the livers of Carassius auratus (C. auratus). The results represented that there were significant changes for the activity of antioxidant enzymes and the levels of glutathione when compared with the untreated groups. So it can be concluded that there are oxidative stresses caused by TBBPA in the livers of C. auratus.3) In order to comprehensively and integrally analyze the oxidative effects caused by TBBPA in the livers of C. auratus, we used a tool, integrated biomarker response (IBR). The index revealed that the fish exposed in the tap water with 3 mg/L TBBPA suffered more oxidative stresses than those in the acid or alkaline conditions.4) Liver and gill tissues were examined histologically to better account for the toxicological impacts of TBBPA. And the results showed epithelial hyperplasia, lamellar aneurisms, mesothelioma, curling of lamella and shortening of lamella in the gills as well as pyknotic nuclei, hyalinization and deformation of nuclei in the livers of C. auratus. In all, this study provides valuable toxicological information of TBBPA and will facilitate a deeper understanding on its potential toxicity in realistic aquatic environments.