[Chemicals and cancer risk (author's transl)]

Environmental factors are considered to be the main causes creating human cancer risks. Some of the topical problems involved, resulting from the existence of defined or discrete carcinogens and so called carcinogenic risk factors, are discussed. Up to now it has been rather difficult to analyse them exactly. Qualitative and quantitative aspects of the assessment of carcinogens and the relevance of short-term tests, long-term bioassays and epidemiological studies are discussed. It is estimated that the possibilities to assess cancer risks have improved during the last few years.