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Enantiomeric signatures of chiral organochlorine pesticides in consumer fish from South China.

Despite the importance of chiral organochlorine pesticide enantiomers in terms of environmental effects, no relevant data have been acquired in consumer fish. The present study determined the residual levels and enantiomer fractions (EFs) of α-HCH, o,p'-DDT, and o,p'-DDD in 11 consumer fish species from South China, including 6 freshwater farmed fish, 3 seawater farmed fish, and 2 wild marine fish. The mean concentrations of α-HCH, o,p'-DDT, and o,p'-DDD were 0.27, 4.4, and 3.5 ng/g wet, respectively, in all fish samples measured (n = 125). The EFs of α-HCH varied widely, from below the racemic EF of 0.5 to above it. For o,p'-DDT, the (+)-enantiomer dominated in all fish species. On the other hand, all EFs of o,p'-DDD, a metabolite of o,p'-DDT, were below 0.5, suggesting the (-)-enantiomer was preferentially enriched in fish. In addition, all three target analytes showed species dependence of EFs, consistent with results from other previous studies. Moreover, no significant correlations were found between the EFs and concentrations of α-HCH, o,p'-DDT, and o,p'-DDD in red drum, snubnose pompano, and crimson snapper, with the exception of o,p'-DDD in snubnose pompano, in which weak correlations were detected. Nevertheless, more studies are needed to explore the residual levels and toxicity of chiral contaminants in consumer fish or other foodstuff to further develop the human risk assessment framework based on chiral signatures.