[Toxicity and bioaccumulation of isomers of polychlorobiphenyls by the ciliated protozoan Colpidium campylum (Stokes)].

A toxicity and bioaccumulation study was carried out in Colpidium campylum with sixteen pure isomers of mono-, di-, tri-, tetra-, penta-, hexa- and heptachlorobiphenyls and a commercial product: Pyralene 3010, dissolved in alcohol, after factorial study of the summation of effects between PCB and solvent. The position of chlorine atoms on the aromatic rings and their number influence toxicity, probably in relationship to the possibilities of hydroxylation of these molecules. The experimental conditions must be very carefully respected to obtain reproducible results.