Effects of BDE-209 and its mixtures with BDE-47 and BDE-99 on multiple biomarkers in Carassius auratus

•Biomarkers including AChE, EROD, GST, SOD and CAT were used.•The toxicity order of PBDEs was proposed via the integrated biomarker response.•The mixtures showed more negative biological effects than BDE-209 alone.

In the present study, the sublethal effects of BDE-209 and its mixtures with BDE-47 and BDE-99 on goldfish (Carassius auratus) were investigated, and the biomarkers including acetylcholinesterase (AChE) in brain, catalase (CAT), ethoxyresorufin-O-deethylase (EROD), glutathione-S-transferase (GST) and superoxide dismutase (SOD) in liver were determined after 4 days of exposure. AChE and CAT activities were significantly inhibited by BDE-209 and the mixtures at higher dosages (≥1 mg/kg), and exhibited obvious dose–response relationships. EROD, GST and SOD activities were significantly induced by BDE-209 and the mixtures in most cases. Integrated biomarker response (IBR) was calculated by combining multiple biomarkers to single value and used to quantitatively evaluate the toxicological effects of PBDEs. The order of IBR values was BDE-209/BDE-99 > BDE-209/BDE-99/BDE-47 > BDE-209/BDE-47 > BDE-209. It suggests that IBR might be a useful tool for quantification of integrated biological effects induced by coexisted contaminants toward fish.