Any substance, radionuclide or radiation that promotes carcinogenesis, the formation of cancer due to the ability to damage the genome or disrupt the cellular metabolic processes. Several radioactive substances are considered Carcinogens, but their carcinogenic activity is attributed to the radiation (e.g., gamma rays and alpha particles, which they emit). Common examples of non-radioactive Carcinogens include chemicals such as inhaled asbestos and certain dioxins.
International organizations and agencies in various countries have classification systems for Carcinogens. For example, the International Agency for Research on Cancer classifies Carcinogens as “known human carcinogens” and “probable human carcinogens,” whereas the US National Toxicology Program classifies Carcinogens as “known to be human carcinogens” and “reasonably anticipated to be human carcinogens.” Regulatory regimes around the world impose restrictions on substances falling into these classifications.