Congener-specific distribution of polybrominated diphenyl ethers in fish of China: implication for input sources

A total of 390 individual fish, including seven species of freshwater-farmed fish, three species of seawater-farmed fish, and three species of wild marine fish, from China were analyzed to determine the concentrations and congener distribution of polybrominated diphenyl ethers (PBDEs). The levels of Sigma(10)PBDEs (sum of BDEs 28, 47, 66, 100, 99, 85, 154, 153, 138, and 183) in seawater-farmed fish (median, 13.6 ng/g) were significantly higher than those in freshwater-farmed fish (median, 10.1 ng/g) and in wild marine fish (median, 4.5 ng/g) on a lipid-weight basis. Lipid contents positively correlated with Sigma(10)PBDEs concentration (wet wt) in all fish species except for tilapia, bighead carp, bluntsnout bream, and common mullet; however, no significant relationship was found between fish length or weight and Sigma(10)PBDEs concentration except for one fish species. In general, BDE 47 was the dominant congener, with a mean contribution of 53.2%. Brominated diphenyl ether 209 was only detected in 14 samples, reflecting its low bioavailability or high degree of debromination. In addition, the ratios of BDE 47 to BDE 99 and of BDE 100 to BDE 99 in freshwater-farmed fish were significantly higher than those in seawater-farmed and wild marine fish. Freshwater-farmed fish had a relatively higher proportion of BDE 28, whereas seawater-farmed and wild marine fish contained more abundant BDE 66, BDE 100, and BDE 99. The difference in congener distribution might be indicative of different exposure pathways for PBDEs in three types of fish.