Experimental carcinogenicity and bioassays of automobile exhaust condensate and its polycyclic aromatic hydrocarbons

Experiments and activities of members of the German governmental research group are presented in addition to those reported by SCHMAEL (1974) in these proceedings. The description of the biomathematic model for planning and evaluation of experiments is followed by data on the interaction of polycyclic aromatic hydrocarbons (PAH) from the automobile exhaust condensate (AEC). With subcutaneous application similar findings were observed as previously demonstrated by SCHMAEL (1974), who administered the test substances epicutaneously. There was no inhibition effect of tumor development by combining noncarcinogenic PAHs with carcinogenic ones. Intratracheal instillations of BaP have been done to clarify dose-response-relationships. The clearance rate of PAHs from the respiratory tract was investigated as well as the influence exerted by different solvents. A new constructed apparatus for chronic inhalation studies with a convenient particle size is described. According to a fractionating scheme for AEC the relation of the solvent to AEC and its fractions as well as acute and subchronic toxicity of those substances were tested. As a screening method for biological activities of the AEC and its PAHs the sebaceous gland suppression test was used. It demonstrated an approximately 20-times greater acticity on the basis of BaP applied for AEC than for BaP alone