[Distribution characteristics and potential risk of PCBs in surface water from three tributaries of Yangtze River in different periods].

Eighty-one surface water samples were collected from 3 tributaries of the Yangtze River in different periods. Contents of 28 PCB congeners in surface water samples were measured using Varian CP3800/300 GC-MS/MS technique. PCB8, 18, and 28 are the most predominant PCB congeners in the samples from tributaries. The measured level of PCBs in the samples from the Tuo river, downstream of Ouchi River and Songlihongdao tributary were 1.96-2.59 ng x L(-1), 1.84-2.54 ng x L(-1) and 1.52-2.38 ng x L(-1). The average concentrations of PCBs in the samples were lower than USEPA criterion continuous concentration (14 ng x L(-1)), which were also in the same order of magnitude of those reported with lower levels in European and American countries. The estimated cumulative cancer risk for the local residents who drink water from tributaries were 0.15 x 10(-7)-0.26 x 10(-7), which shows that cancer risk are negligible due to PCBs contamination in these samples.