Carcinogens are substances that induce cancer by damaging the genome or through disruption of cellular metabolic processes. Some compounds interact directly with DNA, while others are activated to reactive molecules that can bind with DNA by covalent adducts causing mutations in genes crucial to biological processes. Cigarette smoke is by far the most important and notorious carcinogen. Cigarette smoke contains many carcinogenic substances including polycyclic aromatic hydrocarbons (PAHs), which are known to cause cancer. Nitrites, which are present in many foods, are converted into nitrous acid in the stomach and may then react with amines in food to produce nitrosamines, which are carcinogenic. Aflatoxins produced by Aspergillus flavus are promoter for hepatic cancer. Several cytotoxic drugs are carcinogens especially alkylating agents that interact with DNA. Individuals exposed to certain pesticides may be at risk to the development of certain cancers. Inorganic arsenic exposure has been suggested to be associated with the development of several cancers. Sufficient evidence indicated an association between dioxins and various cancers including soft tissue sarcoma, lymphoma and leukemia. Asbestos has been found to be significantly associated with lung cancer and mesothelioma.
Part of the book: Cancer Causing Substances