Distribution and potential human risk of organochlorine pesticides in market mollusks from Dalian, China.

Levels of organochlorine pesticides (OCPs) were analyzed in mollusk samples collected from markets in Dalian, China. Among 14 OCPs screened, chlordane (Chls), dichlorodiphenyltrichloroethane (DDT) and 1,2,3,4,5,6-hexachlorocyclohexane (HCH) were dominant compounds with the medians of 30.2, 5.31 and 2.03 ng/g wet weight (ww), respectively. Source analysis showed that, much higher concentrations of Chls in mollusk samples were the result of usage of the chemical in the city, HCH in samples were mainly due to historical technical HCH usage, and a small amount of fresh use of DDT might exist, causing high portion of p,p'-DDT in samples. Cumulative distribution functions for the concentrations of the selected OCPs were compared to several threshold criteria, indicating that concentrations in most mollusk samples were lower than the safe lines. The concentration data of selected OCPs were used for risk assessment, and human exposure levels were compared to noncancer and cancer benchmarks.