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 differences in chlorobiphenyls (CBs) in members of marine food chains, including water. Four groups of CBs are distinguished based on the presence/absence of vicinal H-atoms in o,m and/or m,p vicinal H-atoms, according to structure-activity relations for their biotransformation by cytochrome P-450 1A and 2B isozymes. Contents of CBs (X) in water, diatom, mussel, copepod, worm, shrimp, flounder, herring, and harbor porpoise were transformed into molar X/153 ratios (CB-153 is persistent) and plotted against X/153 ratios in diatom, lacking metabolic efficiency. For each metabolic group, a linear plot results. Their slopes indicate relative metabolic efficiencies of cytochrome P-450 isozymes. Indication of PB-type enzyme activity in harbor porpoise, flounder, and herring that was not observed before biochemically is new. Metabolic slopes of CBs can also be used as environmental stress indicators by comparison of slopes in a selected organism in areas with different degrees of contamination.