Polychlorinated biphenyls in clams "Tapes philippinarum" cultured in the Venice Lagoon (Italy): Contamination levels and dietary exposure assessment.

Total polychlorinated biphenyl (PPCB) concentrations calculated as the sum of 21 and the toxicity equivalent (TEQ) of dioxin-like PCBs calculated on the basis of the toxic equivalent factors were assessed in Manila clams Tapes philippinarum cultured in the Venice Lagoon. The concentrations showed a predominance of hexa-chlorobiphenyls followed by penta-, hepta-, tetra- and tri-chlorobiphenyls. The highest levels of PPCB detected were 4.01 ng/g, 2.71 ng/g and 2.68 ng/g wet weight at a southern lagoon site and two northern lagoon sites, respectively. There was a significant differentiation in toxicity levels between culture sites. The highest value was 0.239 pg TEQ/g at a southern lagoon site; the lowest was 0.004 pg TEQ/g at a central lagoon site.