carcinoembryonic antigen

carcinogen A substance or an agent that causes cancer. The International Agency for Research on Cancer has classified many substances and processes as probably or definitely causing cancer in humans. The agency has divided these substances and processes into three categories: agents (such as arsenic, asbestos, and benzene); mixtures (such as in coal tars, tobacco products, and smoke); and exposures (such as in aluminum production, shoe manufacturing and repair, and the rubber industry). One of the best-known carcinogens is ultraviolet radiation from sunlight causing skin cancers.