PCBs in sediments and oysters of Manila Bay, the Philippines

Polychlorinated biphenyls (PCBs) were analyzed in sediment and oyster samples from coastal sites inside Manila Bay. Concentrations for 13 individual PCB congeners and total PCBs are reported herein. Median SigmaPCB concentration in sediments was 0.46 ng g(-1) dry weight (range 0.10-1.5 ng g(-1)) and in oysters it was 15 ng g(-1) dry weight (range 7-73 ng g(-1)). The most contaminated areas of the bay were the coastal zones of Metropolitan Manila and Bulacan province. A significant correlation (p < 0.01) was found between SigmaPCB concentrations in oysters and in sediments. PCB concentrations measured in the bay sediments were below acute toxic levels to marine biota. Nevertheless, consumption of oysters by human population living around the bay might originate SigmaPCB intake rates estimated at about 2.5 times lower than the tolerance limit. Further environmental surveillance is recommended in order to prevent public health risks that may be posed by these chemicals.