The tumor-producing effect of automobile exhaust condensate and fractions thereof. Part II: animal studies.

The induction of squamous cell carcinomas and papillomas in a total of 1,950 mice in a lifelong skin-dropping experiment with different doses of automobile exhaust condensate and its fractions is described. Results of the dose-response studies reported indicate that local oncogenic activity of automobile condensate is contained primarily in its polycyclic aromatic hydrocarbon-fractions. In addition, findings in lung tumor incidences are given. Results of the sebaceous gland suppression screening test were found to be comparable to findings of the skin-dropping experiments.