On the design and selection of polychlorinated biphenyls for use in biological test systems

The polychlorinated biphenyls (PCBs) consist of a large number of individual congeners with varying degree of chlorination and possible substitution patterns. No single congener can be used as a representative congener for the whole class of compounds. Multivariate chemical characterisation (principal component analysis) in combination with factorial design provide tools by which small sets of structurally representative congeners can be determined. These tools are suggested to be used in the design of biological experiments in order to introduce systematic structural variation in the congeners to be tested and to make it possible to construct quantitative structure-activity relationships (QSARs). A QSAR based on bioaccumulation factors (BAFs) in fish for 20 systematically selected PCBs made it possible to predict BAFs for all 134 non-tested tetra-through hepta-chlorinated congeners. The use of these systematic and balanced sets of congeners in the experimental protocol will provide increased knowledge of the environmental behaviour of the PCBs.