Polybrominated diphenyl ethers (PBDEs) were extensively investigated in water, sediment, and biota samples collected from Chaohu Lake basin in China. The total concentrations of eight PBDEs (Σ₈PBDEs) were in the ranges of 0.11–4.48 ng/L, 0.06–5.41 ng/g, and 0.02–1.50 ng/g dry weight (dw) in the water, sediment, and biota samples, respectively. The concentrations showed wide variations in the monitoring area, while the congener profiles in all the water, sediment, and biota samples were generally characterized by only a few compounds, such as BDE-47, BDE-99, and/or BDE-209. The spatial analysis depicted a decreasing trend of PBDEs from west to east Chaohu Lake, consistent with regional industrialization degree. The distributions of PBDE congeners in the biota samples were similar to the compositional profiles in the water, which were dominated by BDE-47 and/or BDE-99. Nevertheless, BDE-47 and BDE-153 in the brain tissue showed a higher accumulative potential than PBDEs in other tissues as well as the whole body, with 96% relative contribution of Σ₈PBDEs. The noncarcinogenic risk values estimated for BDE-47, BDE-99, and BDE-153 indicated that the specific risk associated with the studied water and foodstuffs is limited. However, there is a potential mixture ecotoxicity at three trophic levels at some sampling points in the water, which should draw considerable attention.

Polybrominated diphenyl ethers (PBDEs), which belong to the class of brominated flame-retardants, are widely used in industrial products. PBDEs have been detected in varied environmental matrices and they can induce various toxicities such as neurotoxicity, cytotoxicity, and endocrine-disrupting effects in animals. The main objective of this study was to investigate the effects of 2,2’,4,4’,5,5’-hexabromodiphenyl ether (BDE-153), 2,4-dibromophenol (2,4-DBP), and their mixtures on the endocrine system, including acetylcholinesterase (AChE) of brain, ethoxyresorufin-O-deethylase (EROD), glutathione-S-transferase (GST), and superoxide dismutase (SOD) of liver in crucian carp (Carassius auratus). Fish were exposed to BDE-153 (0.2-100 mg/kg in food), 2,4-DBP (0.2-100 mg/kg in food), and their mixture for seven days. BDE-153 alone or in combination with 2,4-DBP significantly reduced brain AChE activity and increased liver EROD activity while no significant effects were observed for 2,4-DBP alone. The simultaneously elevated GST and SOD activities were found at higher doses of BDE-153 and 2,4-DBP (alone and in combination), and exhibited obvious positive correlation (0.76<R<0.89). With regards to the induction fold of biomarker responses, 2,4-DBP has a lower toxicity than its parent compound BDE-153. However, the joint effects of BDE-153 and 2,4-DBP were not enhanced with regard to the four enzymatic activities.