The safe handling of carcinogens is the handling of cancer causing substances in a safe and responsible manner. Carcinogens are defined as 'a substance or agent that can cause cells to become cancerous by altering their genetic structure so that they multiply continuously and become malignant'. The Australian NOHSC Definitions divides carcinogens into three categories. Category 1 carcinogens are substances known to be carcinogenic to humans. Category 2 carcinogens are substances that should be regarded as if they were carcinogenic to humans. Category 3 carcinogens are defined as substances that have possible carcinogenic effects in humans but about which there is insufficient information to make an assessment. Substances are most often categorised as category 1 carcinogens by epidemiologic