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

Concentrations of the non-ortho substituted (planar) chlorobiphenyls 77, 126 and 169, the mono-ortho substituted chlorobiphenyls 105, 118 and 156 and chlorinated dibenzo-p-dioxins and dibenzofurans have been determined in marine and freshwater fish and shellfish from the Netherlands. There are strong indications for a metabolic degradation of the CBs 77 and 126 in yellow eel (Anguilla anguilla). In all fish and shellfish samples analyzed except in yellow eel the toxic effect of the PCBs which in Dutch fish and shellfish is about 4 times higher than that of chlorinated dibenzo-p-dioxins and dibenzofurans, is caused for 85-90% 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 between the CB 153 concentrations and TCDD-equivalents calculated for PCBs enables a prediction of the TCDD-equivalents from the CB 153 concentrations.