ABSTRACT
Lung cancer seems to be provoked by environmental carcinogens in West Germany. According to the regional differences it is to be supposed that carcinogens are present in cigarette smoke as well as in emissions from various sources. A suitable animal test model is the key to the detection of all carcinogenic components of a complex mixture, and to an assessment of the percentage amount which individual carcinogens contribute to the total activity. The tumor rates observed in pretreated animals might possibly be explained by assuming that some of the complete carcinogens are eliminated or destroyed during fractionation. If the topical application model is used as an indicator for the carcinogenicity of substances, by far the greater part of the carcinogens has to be looked for among the polycyclic aromatic hydrocarbons (PAH). Several authors reported on the separation of air pollutants into PAH-containing and PAH-free fractions.
