PATTERNS OF CHLORINATED BIPHENYL CONGENERS IN HARBOR SEALS (PHOCA-VITULINA) AND IN THEIR FOOD - STATISTICAL-ANALYSIS

Patterns of chlorinated biphenyl (CB) congeners have been compared in two groups of samples, namely blood samples from harbor seals (Phoca v itulina) and muscle tissue samples in the fish with which the seals we re fed. The data originate from a Dutch controlled feeding study, perf ormed in 1981 and 1983. The seals were living in captivity in two sepa rate groups, and the fish samples were plaice (Pleuronectes platessa) from the Dutch part of the Wadden sea and mackerel (Scomber scombrus) from the Atlantic ocean. The levels of CB congeners were different in the two types of fish. The CB congener patterns of these four ''matric es'' were compared by analysis of principal components, and were found to be different in the two groups of harbor seals, which were fed the different types of fish. The corresponding CB congener patterns of th e two groups of fish were also different. There was no indication for a relatively larger impact of biotransformation due to induction of is oforms of the cytochrome P450-system at the higher absolute CB congene r levels in the Wadden sea group of seals compared to the Atlantic gro up of seals. The differentiation between the CB congener patterns in t he two groups of seals in the Dutch study can be ascribed solely to di fferent CB congener patterns in their food. The difference between CB congener patterns in the seals and in their diet can be explained by t he structure-related biotransformation of the CB congeners in the harb or seal.