[Chicken-embryo test. Fase II. Determination of the relative toxicity of eleven 2,3,7,8-chlorosubstituted dioxines and furanes, and three planary OCB's.]

Abstract niet beschikbaarIn order to evaluate the risk of samples contaminated with mixtures polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans and planar biphenyls a chicken embryo bioassay is in development at our Institute. In this bioassay the toxic potency of these compounds is determined by means of the ethoxyresorufin-deethylation (EROD) activity in the microsomal fraction of the chicken embryo liver. The experiments showed a large variation between the basal EROD activities, and the maximal induced EROD activities. The slope for most dose curves was similar. The relative toxicity factors in the chick embryo test determined, were compared to the international (i)-TEFs. The EROD induction by the tetra- and penta-dioxins and -furans showed higher TEF in the chicken embryo compared to the (i)-TEF, and the hexa- and heptachlorinated congeners are undervalued in the chicken embryo assay. Then the chicken embryo assay was used to evaluate the additive aspect of the TEF principle. The results showed that additivity of the congeners was responsible for the EROD induction at a low dose.HIGB VVP VHI;DGM/SVS RIV