2005 年 27 巻 2 号 p. 75-79
Until recently it has been generally considered that genotoxic carcinogens have no threshold in exerting their potential for cancer induction. However, the non-threshold theory can be challenged with regard to assessment of cancer risk to humans. In the present study we show that food-related genotoxic hepatocarcinogens, heterocyclic amines and N-nitroso compounds at low doses do not induce preneoplastic lesions and cancer-related markers in rat medium-term carcinogenicity bioassay. The results imply existence of a threshold, at least practical one, for carcinogenicities of genotoxic carcinogens.