Editing Methanol (section)

===Toxicity===
{{Main|Methanol toxicity}}
{{See also|List of methanol poisoning incidents}}
Ingesting as little as {{Convert|10|mL|USoz|abbr=on}} of pure methanol can cause permanent blindness by destruction of the [[optic nerve]]. {{Convert|30|mL|USoz|abbr=on}} is potentially fatal.<ref name="Vale">{{Cite journal |author=Vale A |title=Methanol |journal=Medicine |volume=35 |issue=12 |pages=633–4 |year=2007|doi=10.1016/j.mpmed.2007.09.014}}</ref> The median lethal dose is {{Convert|100|mL|USoz|abbr=on}}, ''i.e.'', 1–2&nbsp;mL/kg body weight of pure methanol.<ref>{{Cite web|title=Methanol Poisoning Overview|url=http://www.antizol.com/mpoisono.htm|publisher=Antizol|archive-url=https://web.archive.org/web/20111005043548/http://www.antizol.com/mpoisono.htm|archive-date=5 October 2011}}</ref> The [[reference dose]] for methanol is 0.5&nbsp;mg/kg in a day.<ref>{{Cite web|url=http://www.epa.gov/iris/subst/0305.htm|title=Integrated Risk Information System|publisher=US EPA, ORD, NCEA, IRISD|date=15 March 2013|access-date=18 February 2013|archive-date=5 December 2012|archive-url=https://web.archive.org/web/20121205004930/http://www.epa.gov/iris/subst/0305.htm|url-status=live}}</ref><ref>{{cite web |url=https://cfpub.epa.gov/ncea/iris/iris_documents/documents/toxreviews/0305tr.pdf |title=Toxicological Review of Methanol (Noncancer) (CAS No. 67-56-1) In Support of Summary Information on the Integrated Risk Information System (IRIS) |id=EPA/635/R-11/001Fa |publisher=[[United States Environmental Protection Agency|EPA]] |date=September 2013 |access-date=30 March 2021 |archive-date=31 March 2021 |archive-url=https://web.archive.org/web/20210331010417/https://cfpub.epa.gov/ncea/iris/iris_documents/documents/toxreviews/0305tr.pdf |url-status=live}}</ref> Toxic effects begin hours after ingestion, and antidotes can often prevent permanent damage.<ref name="Vale" /> Because of its similarities in both appearance and odor to [[ethanol]] (the alcohol in beverages) or [[isopropyl alcohol]], it is difficult to differentiate between the three.<ref>{{Cite encyclopedia |last=Wade |first=Leroy G. |title=Physical properties of alcohols |url=https://www.britannica.com/science/alcohol/Physical-properties-of-alcohols |access-date=2024-08-18 |encyclopedia=Britannica |language=en}}</ref>

Methanol is [[Toxicity|toxic]] by two mechanisms. First, methanol can be fatal due to effects on the central nervous system, acting as a [[Central nervous system depression|central nervous system depressant]] in the same manner as [[Alcohol intoxication#Acute alcohol poisoning|ethanol poisoning]]. Second, in a process of [[toxication]], it is [[metabolism|metabolised]] to [[formic acid]] (which is present as the formate ion) via [[formaldehyde]] in a process initiated by the [[enzyme]] [[alcohol dehydrogenase]] in the [[liver]].<ref name="Schep">{{Cite journal |vauthors=Schep LJ, Slaughter RJ, Vale JA, Beasley DM |s2cid=6367081 |title=A seaman with blindness and confusion |journal=[[BMJ]] |volume=339 |pages=b3929 |date=2009 |url=http://www.bmj.com/cgi/content/full/339/sep30_1/b3929 |doi=10.1136/bmj.b3929 |pmid=19793790 |access-date=3 October 2009 |archive-date=8 October 2009 |archive-url=https://web.archive.org/web/20091008081309/http://www.bmj.com/cgi/content/full/339/sep30_1/b3929 |url-status=live}}</ref> Methanol is converted to formaldehyde via alcohol dehydrogenase (ADH) and formaldehyde is converted to formic acid (formate) via [[aldehyde dehydrogenase]] (ALDH). The conversion to formate via ALDH proceeds completely, with no detectable formaldehyde remaining.<ref name=noCHOH>{{Cite journal |vauthors=McMartin KE, Martin-Amat G, Noker PE, Tephly TR |title=Lack of a role for formaldehyde in methanol poisoning in the monkey |journal=Biochem. Pharmacol. |volume=28 |issue=5 |pages=645–9 |year=1979 |pmid=109089 |doi= 10.1016/0006-2952(79)90149-7}}</ref> Formate is toxic because it inhibits mitochondrial [[cytochrome c oxidase]], causing [[hypoxia (medical)|hypoxia]] at the cellular level, and [[metabolic acidosis]], among a variety of other metabolic disturbances.<ref>{{Cite journal |vauthors=Liesivuori J, Savolainen H |title=Methanol and formic acid toxicity: biochemical mechanisms |journal=Pharmacol. Toxicol. |volume=69 |issue=3 |pages=157–63 |date=September 1991 |pmid=1665561 |doi= 10.1111/j.1600-0773.1991.tb01290.x}}</ref>

<!-- Epidemiology, prognosis, and history -->
Outbreaks of methanol poisoning have occurred primarily due to contamination of [[Ethanol|drinking alcohol]].<!--<ref name=EM2016 /> --> It is also worth noting that ethanol is a natural antidote to methanol poisoning.<ref>{{cite journal | url=https://academic.oup.com/ajhp/article-abstract/38/7/1024/5200360 | doi=10.1093/ajhp/38.7.1024 | title=Oral ethanol doses in patients with methanol poisoning | date=1981 | last1=Peterson | first1=Charles D. | journal=American Journal of Health-System Pharmacy | volume=38 | issue=7 | pages=1024–1027 }}</ref> Contaminated batches of alcohol contained a much higher concentration of methanol than ethanol, which did not provide a sufficient dose of the antidote and caused it to be ineffective. This is more common in the [[Developing country|developing world]].<ref name=EM2016>{{Cite journal|last1=Beauchamp|first1=GA|last2=Valento|first2=M|title=Toxic Alcohol Ingestion: Prompt Recognition And Management in the Emergency Department|journal=Emergency Medicine Practice|date=September 2016|volume=18|issue=9|pages=1–20|pmid=27538060}}</ref> In 2013 more than 1700 cases nonetheless occurred in the United States.<!--<ref name=Fer2016 /> --> Those affected are often adult men.<ref name=Fer2016>{{Cite book|last1=Ferri|first1=Fred F.|title=Ferri's Clinical Advisor 2017: 5 Books in 1|date=2016|publisher=Elsevier Health Sciences|isbn=978-0-323-44838-3|page=794|url=https://books.google.com/books?id=rRhCDAAAQBAJ&pg=PA794|access-date=22 August 2019|archive-date=10 January 2023|archive-url=https://web.archive.org/web/20230110020409/https://books.google.com/books?id=rRhCDAAAQBAJ&pg=PA794|url-status=live}}</ref> Outcomes may be good with early treatment.<ref name=Kr2012>{{Cite journal|last1=Kruse|first1=JA|title=Methanol and ethylene glycol intoxication|journal=Critical Care Clinics|date=October 2012|volume=28|issue=4|pages=661–711|pmid=22998995|doi=10.1016/j.ccc.2012.07.002}}</ref> Toxicity to methanol was described as early as 1856.<ref>{{Cite book|last1=Clary|first1=John J.|title=The Toxicology of Methanol|date=2013|publisher=John Wiley & Sons|isbn=978-1-118-35310-3|page=3.4.1|url={{Google books |plainurl=y |id=xSs8oDQV4uYC&|page=44}}}}</ref>

Because of its toxic properties, methanol is frequently used as a denaturant additive for ethanol manufactured for industrial uses. This addition of methanol exempts industrial ethanol (commonly known as "[[denatured alcohol]]" or "methylated spirit") from liquor [[Excise tax in the United States|excise taxation]] in the US and other countries.