Editing Formaldehyde (section)

====Tissue fixative and embalming agent====
[[File:Steve O'Shea injecting formalin.jpg|thumb|Injecting a [[giant squid]] specimen with formalin for preservation]]
Formaldehyde preserves or [[Fixation (histology)|fixes]] tissue or cells. The process involves [[cross-link]]ing of primary [[amino group]]s. The European Union has banned the use of formaldehyde as a [[biocide]] (including [[embalming]]) under the [[Biocidal Products Directive]] (98/8/EC) due to its carcinogenic properties.<ref>[http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=CELEX:31998L0008:EN:HTML Directive 98/8/EC of the European Parliament and of the Council of 16 February 1998 concerning the placing of biocidal products on the market] {{Webarchive|url=https://web.archive.org/web/20080219232906/http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=CELEX:31998L0008:EN:HTML |date=19 February 2008}}. ''OJEU'' L123, 24.04.1998, pp.&nbsp;1–63. ([http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=CONSLEG:1998L0008:20080926:EN:PDF consolidated version to 2008-09-26 (PDF)] {{Webarchive|url=https://web.archive.org/web/20100127033519/http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=CONSLEG:1998L0008:20080926:EN:PDF |date=2010-01-27}})</ref><ref>[http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=CELEX:32003R2032:EN:HTML Commission Regulation (EC) No 2032/2003 of 4 November 2003 on the second phase of the 10-year work programme referred to in Article&nbsp;16(2) of Directive&nbsp;98/8/EC of the European Parliament and of the Council concerning the placing of biocidal products on the market, and amending Regulation&nbsp;(EC) No&nbsp;1896/2000] {{Webarchive|url=https://web.archive.org/web/20110612142224/http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=CELEX:32003R2032:EN:HTML |date=12 June 2011}}. ''OJEU'' L307, 24.11.2003, p.&nbsp;1–96. ([http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=CONSLEG:2003R2032:20070104:EN:PDF consolidated version to 2007-01-04 (PDF)] {{Webarchive|url=https://web.archive.org/web/20110614093404/http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=CONSLEG:2003R2032:20070104:EN:PDF |date=2011-06-14}})</ref> Countries with a strong tradition of embalming corpses, such as Ireland and other colder-weather countries, have raised concerns. Despite reports to the contrary,<ref>{{cite web | first = Alkesh | last = Patel | url = http://www.webwire.com/ViewPressRel.asp?aId=41468 | title = Formaldehyde Ban set for 22 September 2007 | publisher = WebWire | date = 2007-07-04 | access-date = 2012-05-19 | archive-url = https://web.archive.org/web/20181212180926/https://www.webwire.com/ViewPressRel.asp?aId=41468 | archive-date = 2018-12-12 | url-status = dead}}</ref> no decision on the inclusion of formaldehyde on Annex&nbsp;I of the Biocidal Products Directive for product-type&nbsp;22 (embalming and taxidermist fluids) had been made {{As of|2009|9|lc=on}}.<ref>{{cite web|url=http://esis.jrc.ec.europa.eu/ |title=European chemical Substances Information System (ESIS) entry for formaldehyde |access-date=2009-09-01 |url-status=dead |archive-url=https://web.archive.org/web/20140101220543/http://esis.jrc.ec.europa.eu/ |archive-date=2014-01-01}}</ref>

Formaldehyde-based crosslinking is exploited in [[ChIP-on-chip]] or [[ChIP-sequencing]] genomics experiments, where DNA-binding proteins are cross-linked to their cognate binding sites on the chromosome and analyzed to determine what genes are regulated by the proteins. Formaldehyde is also used as a denaturing agent in [[RNA]] gel [[electrophoresis]], preventing RNA from forming secondary structures. A solution of 4% formaldehyde fixes pathology tissue specimens at about one mm per hour at room temperature.