CHLOROBIPHENYLS - MODEL COMPOUNDS FOR METABOLISM IN FOOD-CHAIN ORGANISMS AND THEIR POTENTIAL USE AS ECOTOXICOLOGICAL STRESS INDICATORS BY APPLICATION OF THE METABOLIC SLOPE CONCEPT

A model is described to explain the compositional similarities and dif ferences in chlorobiphenyls (CBs) in members of marine food chains, in cluding water. Four groups of CBs are distinguished based on the prese nce/absence of vicinal H-atoms in o,m and/or m,p vicinal H-atoms, acco rding to structure-activity relations for their biotransformation by c ytochrome P-450 1A and 2B isozymes. Contents of CBs (X) in water, diat om, mussel, copepod, worm, shrimp, flounder, herring, and harbor porpo ise were transformed into molar X/153 ratios (CB-153 is persistent) an d plotted against X/153 ratios in diatom, lacking metabolic efficiency . For each metabolic group, a linear plot results. Their slopes indica te relative metabolic efficiencies of cytochrome P-450 isozymes. Indic ation of PB-type enzyme activity in harbor porpoise, flounder, and her ring that was not observed before biochemically is new. Metabolic slop es of CBs can also be used as environmental stress indicators by compa rison of slopes in a selected organism in areas with different degrees of contamination.