Division 3.6.1 Definition United Kingdom Original text. Later amendments are not shown. 3.6.1.1Carcinogenicity means the induction of cancer or an increase in the incidence of cancer occurring after exposure to a substance or mixture. Substances and mixtures which have induced benign and malignant tumours in well performed experimental studies on animals are considered also to be presumed or suspected human carcinogens unless there is strong evidence that the mechanism of tumour formation is not relevant for humans. ← Division 3.6 Division 3.6.1 Division 3.6.1.1 →