Environmental Carcinogens and Mutagens

Abstract

Environmental agents (chemicals, radiation and viruses) can be carcinogens (cancer‐causing substances) and mutagens (substances that alter DNA). The steps from mutagen/carcinogen to tumour involve mutagen/carcinogen activation by metabolism, reaction with DNA to give a DNA adduct and DNA replication of the adduct, resulting in a mutation; a mutation in a cancer gene may result in enhanced growth potential, and ultimately in tumour growth.

Keywords: mutations; cancer; environment; DNA; disease; chemicals; carcinogens; mutagens

Figure 1.

The structures of several chemical carcinogens discussed in the text. Benzo[a]pyrene (B[a]P) is a polycyclic aromatic hydrocarbon (PAH); PAHs are found in soots and are produced by incomplete combustion (e.g. in exhaust gases from internal combustion engines and power plants, cigarette smoke and charred foods). Aflatoxin B1 (AFB1) is a mycotoxin produced by moulds that grow on improperly stored foodstuffs (e.g. peanuts). Two aromatic amines are shown: PhIP, found in charred foods; and benzidine, an industrial chemical. Two alkylating (methylating) agents are shown: dimethylnitrosamine (DMN), found in certain foods; and NNK, found in cigarette smoke.

Figure 2.

The carcinogenesis paradigm, using benzo[a]pyrene as an example (see text). The horizontal arrows lead towards greater toxicity (in particular toward cancer), while the vertical arrows lead toward lesser toxicity.

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Loechler, Edward L(Jan 2003) Environmental Carcinogens and Mutagens. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1038/npg.els.0001477]