HCH and DDT residues in molluscs from Chinese Bohai coastal sites

Mollusk samples representing 20 different species were collected at ten typical coastal sites along the Bohai Sea, China, and concentrations of hexachlorocyclohexanes (HCHs) and DDTs were measured. DDTs were found to be the dominant contaminants, with total concentrations ranging from the limit of detection to 151.01 ng/g. Total HCHs ranged from less than 0.08 to 5.92 ng/g. Of the 87 mollusk samples examined, detectable organochlorine residues were detected in 79. The highest HCH concentrations were found at Laizhou, while the most-contaminated DDT samples were collected at Weihai. Overall, the highest organochlorine concentration of 153.15 ng/g was found in Sinonovacula constricta collected at Yantai, while total concentrations in Ostrea talienwhanensis and Mytilus edulis were 38.74 and 33.91 ng/g, respectively. The mean residue levels found in edible species exceeded the Canadian guidelines and were close to the US guidelines.