Editing Mutagen (section)

===Chemical mutagens===
[[Image:Benzopyrene DNA adduct 1JDG.png|thumb |right |200px |A [[DNA adduct]] (at center) of the mutagenic [[(+)-Benzo(a)pyrene-7,8-dihydrodiol-9,10-epoxide|metabolite]] of [[Benzo(a)pyrene|benzo[''a'']pyrene]] from [[tobacco smoking|tobacco smoke]]]]
Chemical mutagens either directly or indirectly damage DNA. On this basis, they are of 2 types:

====Directly acting chemical mutagens====
They directly damage DNA, but may or may not undergo metabolism to produce promutagens (metabolites that can have higher mutagenic potential than their substrates).
* [[Reactive oxygen species]] (ROS) – These may be [[superoxide]], [[hydroxyl radicals]] and [[hydrogen peroxide]], and large number of these highly reactive species are generated by normal cellular processes, for example as a by-products of mitochondrial [[Electron transport chain|electron transport]], or [[lipid peroxidation]]. As an example of the latter, 15-hydroperoxyeicosatetraenoic acid, a natural product of cellular cyclooxygenases and lipoxygenases, breaks down to form 4-hydroxy-2(''E'')-nonenal, 4-hydroperoxy-2(''E'')-nonenal, 4-oxo-2(''E'')-nonenal, and ''cis''-4,5-epoxy-2(''E'')-decanal; these bifunctional electophils are mutagenic in mammalian cells and may contribute to the development and/or progression of human cancers (see [[15-Hydroxyicosatetraenoic acid]]).<ref>{{cite journal | vauthors = Lee SH, Williams MV, Dubois RN, Blair IA | title = Cyclooxygenase-2-mediated DNA damage | journal = The Journal of Biological Chemistry | volume = 280 | issue = 31 | pages = 28337–46 | date = August 2005 | pmid = 15964853 | doi = 10.1074/jbc.M504178200 | display-authors = 3 | doi-access = free }}</ref> A number of mutagens may also generate these ROS. These ROS may result in the production of many base adducts, as well as DNA strand breaks and crosslinks.
* [[Deamination|Deaminating]] agents, for example [[nitrous acid]] which can cause transition mutations by converting [[cytosine]] to [[uracil]].
* [[Polycyclic aromatic hydrocarbon]]s (PAH), when activated to diol-epoxides can bind to DNA and form adducts.
* [[Alkylation|Alkylating]] agents such as [[ethylnitrosourea]]. The compounds transfer methyl or ethyl group to bases or the backbone phosphate groups. Guanine when alkylated may be mispaired with thymine. Some may cause DNA crosslinking and breakages. [[Nitrosamine]]s are an important group of mutagens found in tobacco, and may also be formed in smoked meats and fish via the interaction of amines in food with nitrites added as preservatives. Other alkylating agents include [[Sulfur mustard|mustard gas]] and [[vinyl chloride]].
* [[Aromatic amines]] and amides have been associated with carcinogenesis since 1895 when German physician [[Ludwig Rehn]] observed high incidence of bladder cancer among workers in German synthetic aromatic amine dye industry. [[2-Acetylaminofluorene]], originally used as a pesticide but may also be found in cooked meat, may cause cancer of the bladder, liver, ear, intestine, thyroid and breast.
* [[Alkaloid]] from plants, such as those from [[Vinca]] species,<ref>{{cite book |doi=10.1016/S0378-6080(05)80467-2 |chapter=Cytostatic drugs |title=Side Effects of Drugs Annual 28 |date=2005 |last1=Lipp |first1=Hans-Peter |last2=Hartmann |first2=Jörg Thomas |last3=Stanley |first3=Andrew |volume=28 |pages=538–551 |isbn=978-0-444-51571-1 }}</ref> may be converted by metabolic processes into the active mutagen or carcinogen.
* [[Bromine]] and some compounds that contain bromine in their chemical structure.<ref>{{cite journal | vauthors = Henderson JP, Byun J, Williams MV, Mueller DM, McCormick ML, Heinecke JW | title = Production of brominating intermediates by myeloperoxidase. A transhalogenation pathway for generating mutagenic nucleobases during inflammation | journal = The Journal of Biological Chemistry | volume = 276 | issue = 11 | pages = 7867–75 | date = March 2001 | pmid = 11096071 | doi = 10.1074/jbc.M005379200 | display-authors = 3 | doi-access = free }}</ref>
* [[Sodium azide]], an [[azide]] salt that is a common reagent in organic synthesis and a component in many car airbag systems
* [[Psoralen]] combined with ultraviolet radiation causes DNA cross-linking and hence chromosome breakage.
* [[Benzene]], an industrial solvent and precursor in the production of drugs, plastics, [[synthetic rubber]] and dyes.
* [[Chromium trioxide]], a highly toxic and oxidizing substance used in electroplating.<ref>{{cite journal | last1=Mamyrbaev | first1=Arstan Abdramanovich | last2=Dzharkenov | first2=Timur Agataevich | last3=Imangazina | first3=Zina Amangalievna | last4=Satybaldieva | first4=Umit Abulkhairovna | title=Mutagenic and carcinogenic actions of chromium and its compounds | journal=Environmental Health and Preventive Medicine | publisher=Springer Science and Business Media LLC | volume=20 | issue=3 | date=2015-04-16 | issn=1342-078X | doi=10.1007/s12199-015-0458-2 | pages=159–167| pmid=25877777 | pmc=4434237| bibcode=2015EHPM...20..159M }}</ref>

====Indirectly acting chemical mutagens====
They are not necessarily mutagenic by themselves, but they produce promutagens mutagenic compounds through metabolic processes in cells.
*[[Polyaromatic hydrocarbon]]s (PAHs)<ref>{{Cite journal |last=Yu |first=Hongtao |date=November 2002 |title=Environmental carcinogenic polycyclic aromatic hydrocarbons: photochemistry and phototoxicity |journal=Journal of Environmental Science and Health. Part C, Environmental Carcinogenesis & Ecotoxicology Reviews |volume=20 |issue=2 |pages=149–183 |doi=10.1081/GNC-120016203 |issn=1059-0501 |pmc=3812823 |pmid=12515673|bibcode=2002JESHC..20..149Y }}</ref>
*[[Aromatic amine]]s<ref>{{Cite book |last1=Cooke |first1=M. |last2=Dennis |first2=A. J. |date=1986-01-01 |title=Polynuclear aromatic hydrocarbons: Chemistry, characterization and carcinogenesis |osti=7252502 |url=https://www.osti.gov/biblio/7252502}}</ref>
*[[Benzene]]<ref>{{Cite journal |last1=Nishikawa |first1=Takuro |last2=Miyahara |first2=Emiko |last3=Horiuchi |first3=Masahisa |last4=Izumo |first4=Kimiko |last5=Okamoto |first5=Yasuhiro |last6=Kawai |first6=Yoshichika |last7=Kawano |first7=Yoshifumi |last8=Takeuchi |first8=Toru |date=January 2012 |title=Benzene metabolite 1,2,4-benzenetriol induces halogenated DNA and tyrosines representing halogenative stress in the HL-60 human myeloid cell line |journal=Environmental Health Perspectives |volume=120 |issue=1 |pages=62–67 |doi=10.1289/ehp.1103437 |issn=1552-9924 |pmc=3261936 |pmid=21859636|bibcode=2012EnvHP.120...62N }}</ref>

Some chemical mutagens additionally require [[UV light|UV]] or [[visible light]] activation for their mutagenic effect.  These are the {{vanchor|photomutagens|Photomutagen}}, which include [[furocoumarin]]s and [[limettin]].<ref>{{cite journal|last1=Raquet|first1=N|last2=Schrenk|first2=D|title=Relative photomutagenicity of furocoumarins and limettin in the hypoxanthine phosphoribosyl transferase assay in V79 cells.|journal=Chemical Research in Toxicology|date=September 2009|volume=22|issue=9|pages=1639–47|pmid=19725558|doi=10.1021/tx9002287}}</ref>