NON-ORTHO AND MONO-ORTHO SUBSTITUTED CHLOROBIPHENYLS AND CHLORINATED DIBENZO-P-DIOXINS AND DIBENZOFURANS IN MARINE AND FRESH-WATER FISH ANDSHELLFISH FROM THE NETHERLANDS

Concentrations of the non-ortho substituted (planar) chlorobiphenyls 7 7, 126 and 169, the mono-ortho substituted chlorobiphenyls 105, 118 an d 156 and chlorinated dibenzo-p-dioxins and dibenzofurans have been de termined in marine and freshwater fish and shellfish from the Netherla nds. There are strong indications for a metabolic degradation of the C Bs 77 and 126 in yellow eel (Anguilla anguilla). In all fish and shell fish samples analyzed except in yellow eel the toxic effect of the PCB s which in Dutch fish and shellfish is about 4 times higher than that of chlorinated dibenzo-p-dioxins and dibenzofurans, is caused for 85-9 0% by the CBs 126 and 77. In yellow eel the toxic effect of the PCB is caused for 85-90% by the CBs 126, 156 and 118. The correlation betwee n the CB 153 concentrations and TCDD-equivalents calculated for PCBs e nables a prediction of the TCDD-equivalents from the CB 153 concentrat ions.