Evaluation of 2,3,7,8 specific congener and toxic potency of persistent polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans in cetaceans from the Mediterranean Sea, Italy

The present study investigates individual 2,3,7,8-substituted polychlorinat ed dibenzo-p-dioxin (PCDD) and polychlorinated dibenzofuran (PCDF) concentr ations in cetaceans and assesses the PCDD and PCDF contributions to the tot al TCDD equivalent concentration. Liver samples of a variety of cetaceans s pecies found stranded along the Italian coasts during the period of 1987-19 92 were analyzed for PCDDs and PCDFs. The main aims were to scrutinize leve ls and patterns of PCDDs and PCDFs for the first time in cetaceans from the Mediterranean Sea and to estimate whether chlorinated compounds mentioned are implicated in the exceptionally high mortality of dolphins that occurre d in the Mediterranean Sea during 1990-1992. PCDD and PCDF profiles were do minated by congeners OCCD and OCDF. The new toxic equivalency factors recom mended by WHO in 1997 were used for calculation of dioxin-like toxicity. On the basis of our previous study of PCBs, the overall TEQ calculated from t he 2,3,7,8-substituted PCDDs and PCDFs do not contribute as much dioxin-lik e toxicity as PCBs.