View source for Sodium nitrite

{{Short description|Chemical compound}}
{{Distinguish|sodium nitrate|sodium nitride|nitratine}}
{{Redirect|E250|the mobile phone|Samsung SGH-E250}}
{{Use dmy dates|date=March 2024}}
{{cs1 config|name-list-style=vanc|display-authors=6}}
{{chembox
| Verifiedfields = changed
| Watchedfields  = changed
| verifiedrevid  = 477163131
| Name           = 
| ImageFile      = Sodium nitrite.svg
| ImageClass     = skin-invert
| ImageFileL1    = Nitrite-3D-vdW.png
| ImageClassL1   = bg-transparent
| ImageNameL1    = The nitrite anion (space-filling model)
| ImageFileR1    = Sodium-3D.png
| ImageClassR1 = bg-transparent  
| ImageSizeR1    = 80px
| ImageNameR1    = The sodium cation
| ImageFile2     = Natriumnitrit Elementarzelle.png
| ImageCaption2  = Unit cell of sodium nitrite under standard conditions
| ImageFile3     = Sodium nitrite crystals.jpg
| ImageName3     = Sodium nitrite
| OtherNames     = 
| IUPACName      = Sodium nitrite
| PIN            = Sodium nitrite
| SystematicName = 
| pronounce      = 
| Section1       = {{Chembox Identifiers
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 22689
| ChEBI_Ref = {{ebicite|changed|EBI}} 
| ChEBI = 78870
| ChEMBL_Ref = {{ebicite|correct|EBI}}
| ChEMBL = 93268
| KEGG = D05865
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = M0KG633D4F
| InChI = 1/HNO2.Na/c2-1-3;/h(H,2,3);/q;+1/p-1
| InChIKey = LPXPTNMVRIOKMN-REWHXWOFAO
| SMILES = N(=O)[O-].[Na+]
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/HNO2.Na/c2-1-3;/h(H,2,3);/q;+1/p-1
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = LPXPTNMVRIOKMN-UHFFFAOYSA-M
| CASNo = 7632-00-0
| CASNo_Ref = {{cascite|correct|CAS}}
| PubChem = 23668193
| UNNumber = 1500 3287
| EINECS = 231-555-9
| RTECS = RA1225000
 }}
| Section2       = {{Chembox Properties
| Formula = {{chem2|NaNO2}}
| MolarMass = 68.9953 g/mol
| Appearance = white or slightly yellowish crystalline solid
| Density = 2.168 g/cm<sup>3</sup>
| Solubility = {{ubl|71.4 g/(100 mL) (0&nbsp;°C)|84.8 g/(100 mL) (25&nbsp;°C)|160 g/(100 mL) (100&nbsp;°C)}}
| Solvent1 = methanol
| Solubility1 = 4.4 g/(100 mL)
| Solvent2 = ethanol
| Solubility2 = Soluble
| Solvent3 = diethyl ether
| Solubility3 = 0.3 g/(100 mL)
| Solvent4 = ammonia
| Solubility4 = Very soluble
| MeltingPtC = 271
| MeltingPt_notes = (decomposes at 320&nbsp;°C)
| pKa = ~9
| RefractIndex = 1.65
| MagSus = −14.5·10<sup>−6</sup> cm<sup>3</sup>/mol
 }}
| Section3       = {{Chembox Structure
| Coordination =
| CrystalStruct = [[Orthorhombic]]
| Structure_ref = <ref>{{cite journal | vauthors = Gohda T, Ichikawa M |title=The Refinement of the Structure of Ferroelectric Sodium Nitrite |journal=Journal of the Korean Physical Society |volume=29 |date=November 1996 |pages=551–554}}</ref>
| SpaceGroup = Im2m
| LattConst_a = 3.5653(8)&nbsp;Å
| LattConst_b = 5.5728(7)&nbsp;Å
| LattConst_c = 5.3846(13)&nbsp;Å
| UnitCellFormulas = 2
 }}
| Section4       = 
| Section5       = {{Chembox Thermochemistry
| DeltaHf = −359&nbsp;kJ/mol<ref name=b1>{{cite book| vauthors = Zumdahl SS |title =Chemical Principles |edition=6th| publisher = Houghton Mifflin Company| year = 2009| isbn = 978-0-618-94690-7|page=A23}}</ref>
| DeltaGf = −295 kJ/mol
| Entropy = 106 J/(mol·K)
 }}
| Section6       = {{Chembox Pharmacology
| ATCCode_prefix = V03
| ATCCode_suffix = AB08
}}
| Section7       = {{Chembox Hazards
| ExternalSDS = {{cite web | title = Sodium nitrite | work = Safety Data Sheet | publisher = Sigma-Aldrich | date = 28 December 2022 | url = https://www.sigmaaldrich.com/DE/en/sds/aldrich/563218}}
| NFPA-H = 3
| NFPA-F = 0
| NFPA-R = 1
| NFPA-S = OX
| GHS_ref = <ref>{{cite web |title=GESTIS-Stoffdatenbank sodium nitrite |url=https://gestis.dguv.de/data?name=001380&lang=en |website=gestis.dguv.de |access-date=10 December 2021}}</ref>
| GHSPictograms = {{GHS03}}{{GHS06}}{{GHS09}}
| GHSSignalWord = Danger
| HPhrases = {{H-phrases|272|301|319|400}}
| PPhrases = {{P-phrases|220|273|301+310|305+351+338}}
| FlashPt =
| AutoignitionPtC = 489
| LD50 = 180 mg/kg (rats, oral)
 }}
| Section8       = {{Chembox Related
| OtherAnions = [[Sodium nitrate]]
| OtherCations = {{ubl|[[Potassium nitrite]]|[[Ammonium nitrite]]|[[Lithium nitrite]]|[[Silver nitrite]]}}
| OtherCompounds = [[Nitrous acid]]
 }}
}}

'''Sodium nitrite''' is an [[inorganic compound]] with the [[chemical formula]] {{chem2|NaNO2|auto=1}}. It is a white to slightly yellowish crystalline powder that is very soluble in water and is [[hygroscopic]]. From an industrial perspective, it is the most important [[nitrite]] salt. It is a precursor to a variety of organic compounds, such as pharmaceuticals, dyes, and pesticides, but it is probably best known as a food additive used in [[processed meat]]s and (in some countries) in fish products.<ref name=Ullmann>{{cite book |title=Ullmann's Encyclopedia of Industrial Chemistry |vauthors=Laue W, Thiemann M, Scheibler E, Wiegand KW |chapter=Nitrates and Nitrites |year=2006 |doi=10.1002/14356007.a17_265 |isbn=978-3-527-30673-2}}</ref>

== Uses ==

=== Industrial chemistry ===
The main use of sodium nitrite is for the industrial production of organonitrogen compounds. It is a reagent for conversion of [[amine]]s into [[diazo]] compounds, which are key precursors to many dyes, such as [[diazo dye]]s. [[Nitroso compound]]s are produced from nitrites. These are used in the rubber industry.<ref name=Ullmann/>

It is used in a variety of metallurgical applications, for [[Phosphate conversion coating|phosphatizing]] and detinning.<ref name=Ullmann/>

Sodium nitrite is an effective [[corrosion inhibitor]] and is used as an additive in industrial greases,<ref>{{cite journal | vauthors = Krakhmalev SI, Vorotnikova VA, Ten NV, Taranova NV |year=1984 |title=Determination of sodium nitrite in complex sodium oils|journal=Chemistry and Technology of Fuels and Oils |volume=20 |issue=12 |pages=612–613 |doi=10.1007/BF00726438 |s2cid=94383988}}</ref> as an aqueous solution in closed loop cooling systems, and in a molten state as a heat transfer medium.<ref>{{cite web |url=http://www.generalchemical.com/sodium-nitrite.html |title=Sodium Nitrite |publisher=General Chemical |access-date=28 September 2012 |archive-date=22 May 2013 |archive-url=https://web.archive.org/web/20130522045713/http://www.generalchemical.com/sodium-nitrite.html }}</ref>

=== Food additive and preservative ===
Sodium nitrite is used to speed up the [[Curing (food preservation)|curing]] of meat,<ref name=Wilson>{{cite news |vauthors=Wilson B |date=1 March 2018 |title=Yes, bacon really is killing us |url=https://www.theguardian.com/news/2018/mar/01/bacon-cancer-processed-meats-nitrates-nitrites-sausages |url-status=live |work=[[The Guardian]] |location=London |language=en-GB |issn=0261-3077 |archive-url=https://web.archive.org/web/20210210183650/https://www.theguardian.com/news/2018/mar/01/bacon-cancer-processed-meats-nitrates-nitrites-sausages |archive-date=10 February 2021 |access-date=14 February 2021 |quote=The firms who sold nitrite powders to ham-makers spoke quite openly about how the main advantage was to increase profit margins by speeding up production.}}</ref> inhibit the germination of ''[[Clostridium botulinum]]'' spores, and also impart an attractive pink color.<ref>{{cite journal |vauthors=Lerfall J, Østerlie M |title=Use of sodium nitrite in salt-curing of Atlantic salmon (Salmo salar L.) – Impact on product quality |journal=[[Food Chemistry (journal)|Food Chemistry]] |date=February 2011 |volume=124 |issue=3 |pages=759–766 |doi=10.1016/j.foodchem.2010.06.092}}</ref><ref name="FSAINitriteInMeat">{{cite web| title = Use and Removal of Nitrite in Meat Products| url = https://www.fsai.ie/faq/use_and_removal_of_nitrite.html#prevent_botulism| access-date = 23 April 2023| archive-url = https://web.archive.org/web/20230309190327/https://www.fsai.ie/faq/use_and_removal_of_nitrite.html| archive-date = 9 March 2023}}</ref> Nitrite reacts with the meat [[myoglobin]] to cause color changes, first converting to nitrosomyoglobin (bright red), then, on heating, to nitrosohemochrome (a pink pigment).<ref>{{cite journal |vauthors=Bailey ME, Frame RW, Naumann HD |title=Cured Meat Pigments, Studies of the Photooxidation of Nitrosomyoglobin |journal=[[Journal of Agricultural and Food Chemistry]] |date=January 1964 |volume=12 |issue=1 |pages=89–93 |doi=10.1021/jf60131a026|bibcode=1964JAFC...12...89B }}</ref>

Historically, [[salt]] has been used for the preservation of meat. The salt-preserved meat product was usually brownish-gray in color. When sodium nitrite is added with the salt, the meat develops a red, then pink color, which is associated with cured meats such as ham, bacon, hot dogs, and bologna.<ref>{{cite web|url=http://www.math.unl.edu/~jump/Center1/Labs/MeatPigmentChemistry.pdf|title="Meat Pigment Chemistry", taken from IFT Mini-Experiments in Food Science Series|access-date=28 January 2019|archive-date=3 December 2019|archive-url=https://web.archive.org/web/20191203111916/http://www.math.unl.edu/~jump/Center1/Labs/MeatPigmentChemistry.pdf}}</ref>

In the early 1900s, irregular curing was commonplace. This led to further research surrounding the use of sodium nitrite as an [[Food additive|additive]] in food, standardizing the amount present in foods to minimize the amount needed while maximizing its food additive role.<ref name="Sindelar Human safety">{{cite journal | vauthors = Sindelar JJ, Milkowski AL | title = Human safety controversies surrounding nitrate and nitrite in the diet | journal = Nitric Oxide | volume = 26 | issue = 4 | pages = 259–266 | date = May 2012 | pmid = 22487433 | doi = 10.1016/j.niox.2012.03.011}}</ref> Through this research, sodium nitrite has been found to give taste and color to the meat and inhibit lipid oxidation that leads to rancidity, with varying degrees of effectiveness for controlling growth of disease-causing [[microorganisms]].<ref name="Sindelar Human safety" /> The ability of sodium nitrite to address the above-mentioned issues has led to production of meat with extended storage life and has improved desirable color and taste. According to scientists working for the meat industry,<ref>{{cite web |url=https://www.ctvnews.ca/lifestyle/article/science-says-are-hot-dogs-healthier-without-added-nitrites/|title=Science Says: Are hot dogs healthier without added nitrites? {{!}} Lifestyle from CTV News|website=www.ctvnews.ca|date=30 June 2017}}</ref> nitrite has improved [[food safety]].<ref name="Sindelar Human safety" /> This view is disputed in the light of the possible carcinogenic effects caused by adding nitrites to meat.<ref name=Wilson/>

Nitrite has the [[E number]] E250. [[Potassium nitrite]] (E249) is used in the same way. It is approved for usage in the European Union,<ref>{{cite web|title=Approved additives and E numbers|url=https://www.food.gov.uk/business-guidance/approved-additives-and-e-numbers|access-date=9 January 2023|website=Food Standards Agency|language=en}}</ref><ref>{{cite web | title = Opinions of the Scientific Committee for Food on: Nitrates and Nitrite |url=http://ec.europa.eu/food/fs/sc/scf/reports/scf_reports_38.pdf| work = Food Science and Techniques | publisher = European Commission|access-date=1 April 2018}}</ref> USA,<ref>US Food and Drug Administration: {{cite web |url=https://www.fda.gov/Food/FoodIngredientsPackaging/FoodAdditives/ucm191033.htm#ftnT |archive-url=https://web.archive.org/web/20100108135705/http://www.fda.gov/Food/FoodIngredientsPackaging/FoodAdditives/ucm191033.htm#ftnT |archive-date=8 January 2010 |title=Listing of Food Additives Status Part II |website=[[Food and Drug Administration]] |access-date=27 October 2011}}</ref> and Australia and New Zealand.<ref>{{cite web |title=Australia New Zealand Food Standards Code - Standard 1.2.4 - Labelling of Ingredients |url=http://www.legislation.gov.au/Details/F2011C00827/Html/Text |access-date=9 January 2023 |website=www.legislation.gov.au |language=en}}</ref>

In meat processing, sodium nitrite is never used in a pure state but always mixed with common [[salt]]. This mixture is known as nitrited salt, [[curing salt]] or nitrited curing salt. In Europe, nitrited curing salt contains between 99.1% and 99.5% common salt and between 0.5% and 0.9% nitrite. In the US, nitrited curing salt is dosed at 6.25%<ref name="Gisslen2006">{{cite book | vauthors = Gisslen W | title = Professional Cooking, College Version | chapter = Sausages and Cured Foods  | chapter-url = https://books.google.com/books?id=hxcH5o9QeywC&pg=PA827 | page = 827 | year = 2006 | location = Hoboken, New Jersey | publisher = John Wiley & Sons | isbn = 978-0-471-66374-4 | access-date = 2013-08-16 }}</ref> and must be remixed with salt before use.<ref>{{cite book |vauthors=Coudray G |title=Who poisoned your bacon? |date=February 2021 |publisher=Icon Books |isbn=978-1-78578-611-2 |pages=xv |url=https://iconbooks.com/ib-title/who-poisoned-your-bacon/}}</ref>

==== Color and taste ====
The appearance and taste of meat is an important component of consumer acceptance.<ref name="Sindelar Human safety" /> Sodium nitrite is responsible for the desirable red color (or shaded pink) of meat.<ref name="Sindelar Human safety" /> Very little nitrite is needed to induce this change.<ref name="Sindelar Human safety" /> It has been reported that as little as 2 to 14 parts per million (ppm) is needed to induce this desirable color change.<ref name="Sindelar One" /> However, to extend the lifespan of this color change, significantly higher levels are needed.<ref name="Sindelar One" /> The mechanism responsible for this color change is the formation of nitrosylating agents by nitrite, which has the ability to transfer [[nitric oxide]] that subsequently reacts with myoglobin to produce the cured meat color.<ref name="Sindelar One" /> The unique taste associated with cured meat is also affected by the addition of sodium nitrite.<ref name="Sindelar Human safety" /> However, the mechanism underlying this change in taste is still not fully understood.<ref name="Sindelar One" />

==== Inhibition of microbial pathogens ====
In conjunction with salt and pH levels, sodium nitrite reduces the ability of ''[[Clostridium botulinum]]'' spores to grow to the point of producing toxin.<ref name="FSAINitriteInMeat" /><ref>{{cite journal | vauthors = Lee S, Lee H, Kim S, Lee J, Ha J, Choi Y, Oh H, Choi KH, Yoon Y | title = Microbiological safety of processed meat products formulated with low nitrite concentration - A review | journal = Asian-Australasian Journal of Animal Sciences | volume = 31 | issue = 8 | pages = 1073–1077 | date = August 2018 | pmid = 29531192 | pmc = 6043430 | doi = 10.5713/ajas.17.0675 }}</ref> Some dry-cured meat products are manufactured without nitrites. For example, [[Parma ham]], which has been produced without nitrite since 1993, was reported in 2018 to have caused no cases of botulism. This is because the interior of the muscle is sterile and the surface is exposed to oxygen.<ref name=Wilson/> Other manufacture processes do not assure these conditions, and reduction of nitrite results in toxin production.<ref>{{cite journal | vauthors = Lebrun S, Van Nieuwenhuysen T, Crèvecoeur S, Vanleyssem R, Thimister J, Denayer S, Jeuge S, Daube G, Clinquart A, Fremaux B | title = Influence of reduced levels or suppression of sodium nitrite on the outgrowth and toxinogenesis of psychrotrophic Clostridium botulinum Group II type B in cooked ham | journal = International Journal of Food Microbiology | volume = 334 | article-number = 108853 | date = December 2020 | pmid = 32932195 | doi = 10.1016/j.ijfoodmicro.2020.108853 }}</ref>

Sodium nitrite has shown varying degrees of effectiveness for controlling growth of other spoilage or disease causing microorganisms.<ref name="Sindelar Human safety" /> Although the inhibitory mechanisms are not well known, its effectiveness depends on several factors including residual nitrite level, [[pH]], salt concentration, reductants present and [[iron]] content.<ref name="Sindelar One">{{cite journal |vauthors=Sindelar J, Milkowski A |date=November 2011 |title=Sodium Nitrite in Processed Meat and Poultry Meats: A Review of Curing and Examining the Risk/Benefit of Its Use |url=http://www.meatscience.org/docs/default-source/publications-resources/white-papers/2011-11-amsa-nitrite-white-paper.pdf?sfvrsn=8 |journal=American Meat Science Association |volume=3 |pages=1–14}}</ref> The type of [[bacteria]] also affects sodium nitrite's effectiveness.<ref name="Sindelar One"/> It is generally agreed that sodium nitrite is not effective for controlling [[Gram-negative]] enteric pathogens such as ''[[Salmonella]]'' and ''[[Escherichia coli]]''.<ref name="Sindelar One" />

Other food additives (such as [[Lactic acid|lactate]] and [[sorbate]]) provide similar protection against bacteria, but do not provide the desired pink color.<ref>{{cite journal | vauthors = Seward RA, Deibel RH, Lindsay RC | title = Effects of potassium sorbate and other antibotulinal agents on germination and outgrowth of Clostridium botulinum type E spores in microcultures | journal = Applied and Environmental Microbiology | volume = 44 | issue = 5 | pages = 1212–1221 | date = November 1982 | pmid = 6758699 | pmc = 242170 | doi = 10.1128/AEM.44.5.1212-1221.1982 | bibcode = 1982ApEnM..44.1212S}}</ref><ref>{{cite journal | vauthors = Sofos JN, Busta FF, Bhothipaksa K, Allen CE, Robach MC, Paquette MW |title=Effects of various concentrations of sodium nitrite and potassium sorbate on Clostridium botulinum toxin production in commercially prepared bacon |journal=Journal of Food Science |date=September 1980 |volume=45 |issue=5 |pages=1285–1292 |doi=10.1111/j.1365-2621.1980.tb06539.x}}</ref><ref>{{cite journal | vauthors = Linton M, Connolly M, Houston L, Patterson MF |title=The control of Clostridium botulinum during extended storage of pressure-treated, cooked chicken |journal=Food Control |date=March 2014 |volume=37 |pages=104–108 |doi=10.1016/j.foodcont.2013.09.042}}</ref><ref>{{cite journal | vauthors = Alnoman M, Udompijitkul P, Paredes-Sabja D, Sarker MR | title = The inhibitory effects of sorbate and benzoate against Clostridium perfringens type A isolates | journal = Food Microbiology | volume = 48 | pages = 89–98 | date = June 2015 | pmid = 25790996 | doi = 10.1016/j.fm.2014.12.007 }}</ref>

==== Inhibition of lipid peroxidation ====
Sodium nitrite is also able to effectively delay the development of oxidative [[rancidity]].<ref name="Sindelar One" /> [[Lipid peroxidation]] is considered to be a major reason for the deterioration of quality of meat products (rancidity and unappetizing flavors).<ref name="Sindelar One" /> Sodium nitrite acts as an [[antioxidant]] in a mechanism similar to the one responsible for the coloring effect.<ref name="Sindelar One" /> Nitrite reacts with [[heme]] proteins and metal ions, neutralizing [[free radicals]] by [[nitric oxide]] (one of its byproducts).<ref name="Sindelar One" /> Neutralization of these free radicals terminates the cycle of [[lipid oxidation]] that leads to rancidity.<ref name="Sindelar One" />

=== Medication ===
{{Infobox drug
| IUPAC_name = 
| image = Natriumnitrit.png
| image_class = skin-invert-image
| alt = 
| caption = Chemical structure

<!-- Clinical data -->
| pronounce =
| tradename = 
| Drugs.com = {{Drugs.com|pro|sodium-nitrite-injection}}
| MedlinePlus = 
| pregnancy_AU = 
| pregnancy_AU_comment = Exempt<ref>{{Cite web | title=Therapeutic goods exempted from pregnancy categorisation {{!}} Therapeutic Goods Administration (TGA) | url=https://www.tga.gov.au/therapeutic-goods-exempted-pregnancy-categorisation | archive-url=https://web.archive.org/web/20150622174355/https://www.tga.gov.au/therapeutic-goods-exempted-pregnancy-categorisation | access-date=2024-12-25 | archive-date=2015-06-22}}</ref>
| pregnancy_category= 
| routes_of_administration = 
| class = 
| ATC_prefix = V03
| ATC_suffix = AB08

| legal_AU = S4
| legal_AU_comment = <ref>{{cite web | title=Prescription medicines: registration of new generic medicines and biosimilar medicines, 2017 | website=Therapeutic Goods Administration (TGA) | date=21 June 2022 | url=https://www.tga.gov.au/resources/publication/publications/prescription-medicines-registration-new-generic-medicines-and-biosimilar-medicines-2017 | access-date=30 March 2024}}</ref>
| legal_CA = <!-- OTC, Rx-only, Schedule I, II, III, IV, V, VI, VII, VIII -->
| legal_DE = <!-- Anlage I, II, III -->
| legal_NZ = <!-- Class A, B, C -->
| legal_UK = <!-- GSL, P, POM, CD, CD Lic, CD POM, CD No Reg POM, CD (Benz) POM, CD (Anab) POM or CD Inv POM / Class A, B, C -->
| legal_US = Rx-only
| legal_UN = <!-- N I, II, III, IV / P I, II, III, IV-->
| legal_status = <!-- Free text -->

<!-- Pharmacokinetic data -->
| bioavailability = 
| protein_bound = 
| metabolism = 
| metabolites =
| onset = 
| elimination_half-life = 
| duration_of_action =
| excretion =

<!-- Identifiers -->
| CAS_number = 7632-00-0 
| PubChem = 24269
| DrugBank = DB09112
| ChemSpiderID = 22689
| UNII = M0KG633D4F
| KEGG = D05865
| synonyms =

<!-- Chemical and physical data -->
| Na = 1 | N =1 | O = 2
| smiles = N(=O)[O-].[Na+]
| StdInChI = 1S/HNO2.Na/c2-1-3;/h(H,2,3);/q;+1/p-1
| StdInChIKey = LPXPTNMVRIOKMN-UHFFFAOYSA-M
}}
'''Sodium nitrite''' is used as a medication together with [[Sodium thiosulfate (medical use)|sodium thiosulfate]] to treat [[cyanide poisoning]].<ref name=WHO2008/> It is recommended only in severe cases of cyanide poisoning and has largely been replaced by use of [[hydroxocobalamin]],<ref name="UK2017">{{cite web |title=Sodium Nitrite Solution for Injection - Summary of Product Characteristics (SPC) - (eMC) |url=https://www.medicines.org.uk/emc/medicine/32282 |website=www.medicines.org.uk |access-date=15 January 2017|url-status=live |archive-url=https://web.archive.org/web/20170918184748/https://www.medicines.org.uk/emc/medicine/32282 |archive-date=18 September 2017}}</ref> a form of [[vitamin B12]], but given in much higher doses than needed nutritionally.<ref>{{cite journal | vauthors = Streitz MJ, Bebarta VS, Borys DJ, Morgan DL | title = Patterns of cyanide antidote use since regulatory approval of hydroxocobalamin in the United States | journal = American Journal of Therapeutics | volume = 21 | issue = 4 | pages = 244–249 | date = July–August 2014 | pmid = 23689094 | doi = 10.1097/MJT.0b013e31824ea656 | s2cid = 21116328}}</ref>
In those who have both cyanide poisoning and [[carbon monoxide poisoning]] sodium thiosulfate by itself is usually recommended if the facility does not have sufficient [[hydroxycobalamin]].<ref>{{cite book | vauthors = Graham J, Traylor J | chapter = Cyanide Toxicity |date=2023 | chapter-url = https://www.ncbi.nlm.nih.gov/books/NBK507796/ | title = StatPearls |access-date=7 December 2023 |place=Treasure Island (FL) |publisher=StatPearls Publishing |pmid=29939573}}</ref><ref>{{cite book |vauthors=Baren JM |title=Pediatric Emergency Medicine |date=2008 |publisher=Elsevier Health Sciences |isbn=978-1-4160-0087-7 |page=1018 |url=https://books.google.com/books?id=wpvux6RS-jsC&pg=PA1018 |language=en |url-status=live |archive-url=https://web.archive.org/web/20170116172656/https://books.google.ca/books?id=wpvux6RS-jsC&pg=PA1018 |archive-date=16 January 2017 |via=[[Google Books]]}}</ref> It is given by [[intravenous infusion|slow injection into a vein]].<ref name=WHO2008>{{cite book |title=WHO Model Formulary 2008 |year=2009 |isbn=978-92-4-154765-9 |vauthors=((World Health Organization)) |veditors=Stuart MC, Kouimtzi M, Hill SR |hdl=10665/44053 |author-link=World Health Organization |publisher=World Health Organization |hdl-access=free |page=65}}</ref>

{{chem2|NaNO2}} side effects are chiefly related to creation of methemoglobinemia and vasodilation. Side effects can include [[low blood pressure]], [[headache]], [[shortness of breath]], [[loss of consciousness]], and vomiting.<ref name=WHO2008/> Greater care should be taken in people with underlying heart disease.<ref name=WHO2008/> The patient's levels of [[methemoglobin]] should be regularly checked during treatment.<ref name=WHO2008/> While not well studied during pregnancy, there is some evidence of potential harm to the baby.<ref name=Pro2017/> Sodium nitrite works by creating methemoglobin, where the iron atom at the center of the heme group is in the oxidized ferric ({{chem2|Fe(3+)}}) state, which binds with cyanide with greater affinity than its binding to the [[cytochrome C oxidase]], and thus removes it from blocking the metabolic function of [[mitochondria]].<ref name=Pro2017>{{cite web |title=Sodium Nitrite Injection - FDA prescribing information, side effects and uses |url=https://www.drugs.com/pro/sodium-nitrite-injection.html |website=www.drugs.com |url-status=live |archive-url=https://web.archive.org/web/20170118044431/https://www.drugs.com/pro/sodium-nitrite-injection.html |archive-date=18 January 2017}}</ref>

Sodium nitrite came into medical use in the 1920s and 1930s.<ref>{{cite book |vauthors=Dart RC |title=Medical Toxicology |date=2004 |publisher=[[Lippincott Williams & Wilkins]] |isbn=978-0-7817-2845-4 |page=172 |url=https://books.google.com/books?id=BfdighlyGiwC&pg=PA172 |language=en |url-status=live |archive-url=https://web.archive.org/web/20170116172601/https://books.google.ca/books?id=BfdighlyGiwC&pg=PA172 |archive-date=16 January 2017 |via=[[Google Books]]}}</ref><ref>{{cite book |vauthors = Bryan NS, Loscalzo J |title=Nitrite and Nitrate in Human Health and Disease |date=2011 |publisher=Springer Science & Business Media|isbn=978-1-60761-616-0 |page=226 |url=https://books.google.com/books?id=CDkkwVV4aMQC&pg=PA226 |language=en |url-status=live |archive-url=https://web.archive.org/web/20170116173748/https://books.google.ca/books?id=CDkkwVV4aMQC&pg=PA226 |archive-date=16 January 2017 |via=[[Google Books]]}}</ref> It is on the [[WHO Model List of Essential Medicines|World Health Organization's List of Essential Medicines]].<ref name="WHO21st">{{cite book |vauthors=((World Health Organization)) |title=World Health Organization model list of essential medicines: 21st list 2019 |year=2019 |hdl=10665/325771 |author-link=World Health Organization |publisher=World Health Organization |location=Geneva |id=WHO/MVP/EMP/IAU/2019.06. License: CC BY-NC-SA 3.0 IGO |hdl-access=free}}</ref>

=== Suicide ===
Several academic publications in 2020 and 2021 have discussed the toxicity of sodium nitrite, and an apparent recent increase in suicides using sodium nitrite which had been ordered online.<ref>{{harvp|Durão C, ''et al.'', 2020.}}; {{harvp|Durão C, ''et al.'', 2021.}}; {{harvp|Tomsia M, ''et al.'', 2021.}}; {{harvp|McCann SD, Kennedy JM, ''et al.'', 2021.}}; {{harvp|Dean DE, ''et al.'', 2021.}}; {{harvp|Hickey TB, ''et al.'', 2021.}}; {{harvp|Harvey M, ''et al.'', 2010.}}; {{harvp|McCann SD, Tweet MS, Wahl MS, 2021.}}; {{harvp|Sedhai YR, ''et al.'', 2022.}}; {{harvp|Mudan A, ''et al.'', 2020.}}</ref> The usage of sodium nitrite as a suicide method has been heavily discussed on suicide forums, primarily [[Sanctioned Suicide]].<ref name="Where the Despairing Log On, and Learn Ways to Die">{{cite news | vauthors = Twohey M |author-link=Megan Twohey|date=9 December 2021|title=Where the Despairing Log On, and Learn Ways to Die|newspaper=[[The New York Times]] |url=https://www.nytimes.com/interactive/2021/12/09/us/where-the-despairing-log-on.html|access-date=24 July 2022|url-access=subscription}}</ref>

Sodium nitrite was also the focal-point of the ''McCarthy et al. v [[Amazon (company)|Amazon]]'' lawsuit alleging that Amazon knowingly assisted in the deaths of healthy children by selling them "suicide kits" as Amazon's "[[recommendation engine|frequently bought together]]" feature recommended buying sodium nitrite, an [[antiemetic]], and a suicide instruction book together.<ref>{{cite news|title=Amazon 'suicide kits' have led to teen deaths, according to new lawsuit|url=https://arstechnica.com/tech-policy/2022/10/amazon-suicide-kits-have-led-to-teen-deaths-according-to-new-lawsuit/| vauthors = Belanger A |work=[[Ars Technica]]|date=7 October 2022|access-date=26 August 2023}}</ref> This lawsuit was dismissed in June 2023.<ref>{{cite news | vauthors = Stempel J |date=28 June 2023 |title=Judge dismisses lawsuit claiming Amazon sold 'suicide kits' to teenagers |language=en |work=Reuters |url=https://www.reuters.com/legal/judge-dismisses-lawsuit-claiming-amazon-sold-suicide-kits-teenagers-2023-06-28/ |access-date=3 November 2023}}</ref> The online marketplace eBay has globally prohibited the sale of sodium nitrite since 2019.<ref>{{cite web|url=https://www.judiciary.uk/wp-content/uploads/2020/12/2020-0246-Response-from-Ebay-UK-Ltd-Redacted.pdf|date=8 January 2021|title=Re Jason Thompson (deceased) – Sodium Nitrite|author=Director, eBay (UK) Limited|via=[[Judiciaries of the United Kingdom]]|access-date=26 August 2023}}</ref> [[Kenneth Law]], a Canadian distributor of sodium nitrite was prosecuted in 2023 for assisting suicide.<ref>{{cite news|url=https://www.ctvnews.ca/toronto/article/heres-why-the-world-will-be-watching-kenneth-laws-court-battle/|title=Here's why the world will be watching Kenneth Law's court battle|vauthors=Murphy A|publisher=[[CFTO-DT|CTV Toronto]]|date=25 July 2023|access-date=26 August 2023|archive-date=14 January 2025|archive-url=https://web.archive.org/web/20250114173340/https://toronto.ctvnews.ca/here-s-why-the-world-will-be-watching-kenneth-law-s-court-battle-1.6493596|url-status=live}}</ref><ref>{{cite news|url=https://www.bbc.com/news/world-us-canada-66609884|title=88 UK deaths linked to Canada 'poison seller'| vauthors = Crawford A |publisher=[[BBC News]]|date=25 August 2023|access-date=26 August 2023}}</ref> That same year, legislation was introduced in the United States with the aim of deeming sodium nitrite products with a sodium nitrite concentration of greater than 10% by volume to be banned consumer products under the [[Consumer Product Safety Act]].<ref>{{cite web |title=Chemical Used in Suicides Faces Sales Ban Under Proposed Law |url=https://news.bloomberglaw.com/us-law-week/chemical-used-in-suicides-faces-sales-ban-under-proposed-law |access-date=3 November 2023 |website=news.bloomberglaw.com |date=22 June 2023 |language=en}}</ref>

In cases of suspected suicide involving sodium nitrite, it is critical that [[First responder|responding individuals]] administer immediate intravenous [[methylene blue]].<ref>{{cite journal | vauthors = Sheehy MH, Way JL |date=1 November 1974 |title=Nitrite intoxication: Protection with methylene blue and oxygen |journal=Toxicology and Applied Pharmacology |volume=30 |issue=2 |pages=221–226 |doi=10.1016/0041-008X(74)90093-3 |bibcode=1974ToxAP..30..221S |issn=0041-008X}}</ref><ref name=":0">{{cite journal | vauthors = Ehlers P, Bryant SM | title = Immediate methylene blue is critical for sodium nitrite ingestions | journal = The American Journal of Emergency Medicine | volume = 68 | page = 186 | date = June 2023 | pmid = 37120398 | doi = 10.1016/j.ajem.2023.04.034 | s2cid = 258324908}}</ref><ref>{{cite web | vauthors = Su M, McRae M |date=8 September 2022 |title=2022 Health Advisory #22 Poisonings and Death Related to Intentional Sodium Nitrite Ingestions |url=https://www.nyc.gov/assets/doh/downloads/pdf/han/advisory/2022/sodium-nitrate-ingestion-poisonings.pdf |access-date=4 November 2023 |website=[[New York City Department of Health and Mental Hygiene]]}}</ref> Methylene blue is the antidote to the [[methemoglobinemia]] caused by intentional ingestion of sodium nitrite as a suicide agent.<ref>{{cite journal | vauthors = Lee GW, Lee JB |date=16 December 2013 |title=Antidote for acquired methemoglobinemia: methylene blue |url=https://synapse.koreamed.org/articles/1042644 |journal=Journal of the Korean Medical Association |volume=56 |issue=12 |pages=1084–1090 |doi=10.5124/jkma.2013.56.12.1084|doi-access=free}}</ref>

==Toxicity ==
Sodium nitrite is toxic.<ref>{{cite web |title=How toxic is it? |vauthors=Crellin J |url=https://www.ase.org.uk/sites/default/files/chemistry%20PDFs/PDFs/How%20toxic%20is%20it.pdf |access-date=6 February 2022 |website=The Association for Science Educators |orig-date=First published in March 1989, reviewed in 2015}}</ref> The [[median lethal dose|LD<sub>50</sub>]] in rats is 180&nbsp;mg/kg and in humans [[lowest published lethal dose|LD<sub>Lo</sub>]] is 71&nbsp;mg/kg.<ref>{{cite web |title=Safety data for sodium nitrite |archive-url=https://web.archive.org/web/20080410131202/http://msds.chem.ox.ac.uk/SO/sodium_nitrite.html |archive-date=10 April 2008 |url=http://msds.chem.ox.ac.uk/SO/sodium_nitrite.html |work=The Physical and Theoretical Chemistry Laboratory |publisher=[[Oxford University]]}}</ref> The mechanism by which sodium nitrite causes death is [[methemoglobinemia]].<ref>{{cite journal | vauthors = Katabami K, Hayakawa M, Gando S | title = Severe Methemoglobinemia due to Sodium Nitrite Poisoning | journal = Case Reports in Emergency Medicine | volume = 2016 | article-number = 9013816 | date = 3 August 2016 | pmid = 27563472 | pmc = 4987464 | doi = 10.1155/2016/9013816 | doi-access = free}}</ref> The oftentimes severe methemoglobinemia found in sodium nitrite poisoning cases results in systemic [[Hypoxia (medical)|hypoxia]], [[metabolic acidosis]], and [[cyanosis]].<ref>{{cite journal | vauthors = Padovano M, Aromatario M, D'Errico S, Concato M, Manetti F, David MC, Scopetti M, Frati P, Fineschi V | title = Sodium Nitrite Intoxication and Death: Summarizing Evidence to Facilitate Diagnosis | journal = International Journal of Environmental Research and Public Health | volume = 19 | issue = 21 | article-number = 13996 | date = October 2022 | pmid = 36360874 | pmc = 9654862 | doi = 10.3390/ijerph192113996 | doi-access = free}}</ref> The reported<ref>{{cite web |title=Nitrate and Nitrite Poisoning |url=https://www.poison.org/articles/causes-and-symptoms-of-nitrate-nitrite-poisoning-174 |access-date=4 November 2023 |website=www.poison.org |language=en}}</ref> signs of sodium nitrite poisoning are as follows:
{{Blockquote|text=Symptoms of [nitrite] poisoning can vary depending on the amount and duration of the exposure. Those with very mild methemoglobinemia might not have any symptoms at all, or might appear a little pale and feel tired. Moderate-to-severe poisoning is associated with cyanosis (blueness of the skin), confusion, loss of consciousness, seizures, abnormal heart rhythms, and death.}}
With prompt action, sodium nitrite poisoning is reversible using an antidote, [[methylene blue]].<ref name=":0" /> It has been reported<ref>{{cite journal | vauthors = Hickey TB, MacNeil JA, Hansmeyer C, Pickup MJ | title = Fatal methemoglobinemia: A case series highlighting a new trend in intentional sodium nitrite or sodium nitrate ingestion as a method of suicide | journal = Forensic Science International | volume = 326 | article-number = 110907 | date = September 2021 | pmid = 34298207 | doi = 10.1016/j.forsciint.2021.110907}}</ref> that sodium nitrite poisoning can also be detected post-mortem:
{{Blockquote|text=Postmortem detection of [methemoglobinemia] is typically established via screening techniques such as scene evidence suggesting fatal consumption of a toxic salt in addition to the characteristic grey-purple lividity observed upon the body. The diagnosis can be established via postmortem blood testing demonstrating elevated methemoglobin saturation. Additionally, we have confirmed that postmortem MRI in cases of [methemoglobinemia] demonstrates a T1-bright (hyperintense) signal of the blood; both within intracardiac blood on chest MRIs and postmortem blood samples in tubes.}}
Death by sodium nitrite ingestion can happen at lower doses than the previously known [[lowest published lethal dose|LD<sub>Lo</sub>]].<ref>{{cite journal | vauthors = Gowans WJ | title = Fatal methaemoglobinaemia in a dental nurse. A case of sodium nitrite poisoning | journal = The British Journal of General Practice | volume = 40 | issue = 340 | pages = 470–471 | date = November 1990 | pmid = 2271282 | pmc = 1371420}}</ref><ref>{{cite journal | vauthors = Standefer JC, Jones AM, Street E, Inserra R | title = Death associated with nitrite ingestion: report of a case | journal = Journal of Forensic Sciences | volume = 24 | issue = 4 | pages = 768–771 | date = October 1979 | pmid = 541641 | doi = 10.1520/JFS10905J}}</ref> Sodium nitrite has been used for homicide<ref>{{cite news |title=Chinese teacher sentenced to death for poisoning nursery children |url=https://www.bbc.com/news/world-asia-china-54335841 |work=[[BBC News]] |date=29 September 2020}}</ref><ref>{{cite news |title=Teacher in China sentenced to death for poisoning children's porridge |url=https://www.theguardian.com/world/2020/sep/29/teacher-in-china-sentenced-to-death-for-poisoning-childrens-porridge |work=The Guardian |agency=Agence France-Presse in Beijing |date=29 September 2020}}</ref> and suicide.<ref>{{cite news |title='General Hospital' Actress Lindsey Pearlman's Cause of Death Revealed
 |url=https://www.hollywoodreporter.com/news/general-news/lindsey-pearlman-suicide-coroners-office-1235200099/ |work=[[The Hollywood Reporter]] |date=16 August 2022}}</ref><ref>{{cite news |title=Police charge Mississauga man in connection with sale, distribution of sodium nitrite in GTA
 |url=https://www.ctvnews.ca/toronto/article/police-charge-mississauga-man-in-connection-with-sale-distribution-of-sodium-nitrite-in-gta/ |work=[[CTV News]] |date=3 May 2023}}</ref> To prevent accidental intoxication, sodium nitrite (blended with salt) sold as a food additive in the US is dyed bright pink to avoid mistaking it for plain salt or sugar. In other countries, nitrited curing salt is not dyed but is strictly regulated.<ref>{{cite web|url=https://www.fsai.ie/faq/use_and_removal_of_nitrite.html|title=The Use and Removal of Nitrite in Meat Products &#124; FAQs | work = The Food Safety Authority of Ireland|access-date=10 February 2021|archive-date=27 June 2022|archive-url=https://web.archive.org/web/20220627111348/https://www.fsai.ie/faq/use_and_removal_of_nitrite.html}}</ref>

=== Occurrence in vegetables ===
Nitrites do not occur naturally in vegetables in significant quantities,<ref name="Dennis & Wilson 2003 Nitrates and Nitrites">{{cite book |doi=10.1016/B0-12-227055-X/00830-0 |chapter=Nitrates and Nitrites |title=Encyclopedia of Food Sciences and Nutrition |year=2003 |vauthors=Dennis MJ, Wilson LA |pages=4136–4141 |isbn=978-0-12-227055-0}}</ref> but deliberate fermentation of [[celery|celery juice]], for instance, with a naturally high level of nitrates, can produce nitrite levels sufficient for commercial meat curing.<ref>{{cite web |title=Is celery juice a viable alternative to nitrites in cured meats? |url=https://www.mcgill.ca/oss/article/food/celery-juice-viable-alternative-nitrites-cured-meats |access-date=14 September 2022 |website=Office for Science and Society |language=en}}</ref> Boiling vegetables does not affect nitrite levels.<ref name="Leszczyńska">{{cite journal |vauthors=Leszczyńska T, Filipiak-Florkiewicz A, Cieślik E, Sikora E, Pisulewski PM |date=June 2009|title=Effects of some processing methods on nitrate and nitrite changes in cruciferous vegetables |journal=Journal of Food Composition and Analysis |volume=22 |issue=4 |pages=315–321 |doi=10.1016/j.jfca.2008.10.025}}</ref>

The presence of nitrite in animal tissue is a consequence of metabolism of [[nitric oxide]], an important neurotransmitter.<ref>{{cite journal | vauthors = Meulemans A, Delsenne F | title = Measurement of nitrite and nitrate levels in biological samples by capillary electrophoresis | journal = Journal of Chromatography. B, Biomedical Applications | volume = 660 | issue = 2 | pages = 401–404 | date = October 1994 | pmid = 7866533 | doi = 10.1016/0378-4347(94)00310-6}}</ref> Nitric oxide can be created ''[[wiktionary:de novo|de novo]]'' from [[nitric oxide synthase]] utilizing [[arginine]] or from ingested nitrite.<ref>{{cite journal | vauthors = Southan GJ, Srinivasan A | title = Nitrogen oxides and hydroxyguanidines: formation of donors of nitric and nitrous oxides and possible relevance to nitrous oxide formation by nitric oxide synthase | journal = Nitric Oxide | volume = 2 | issue = 4 | pages = 270–286 | date = August 1998 | pmid = 9851368 | doi = 10.1006/niox.1998.0187}}</ref>

=== Pigs ===
Due to sodium nitrite's high level of toxicity to swine (''Sus scrofa'') it is now being developed in Australia to control feral pigs and [[wild boar]].<ref>{{cite conference |vauthors=Lapidge S, Wishart J, Smith M, Staples L |title=Is America Ready for a Humane Feral Pig Toxicant? |conference=Wildlife Damage Management Conference |date=4 May 2009 |location=Saratoga Springs, NY |url=https://digitalcommons.usu.edu/wdmconference/2009/session2/2/}}</ref><ref>{{cite patent |inventor=Cowled BD, Lapidge SJ, Humphrys S, Staples L |title=Nitrite Salts as Poisons in Baits for Omnivores |country=WO |number=2008/104028 |pubdate=2008 |url=http://www.wipo.int/patentscope/search/en/WO2008104028}}</ref> The sodium nitrite induces [[methemoglobinemia]] in swine, i.e. it reduces the amount of oxygen that is released from hemoglobin, so the animal will feel faint and pass out, and then die in a humane manner after first being rendered unconscious.<ref>{{cite book |vauthors=Porter S, Kuchel T |title=Assessing the humaness and efficacy of a new feral pig bait in domestic pigs. Study PC0409 |year=2010 |publisher=Veterinary Services Division, Institute of Medical and Veterinary Science |location=Canberra, South Australia |page=11 |url=http://www.environment.gov.au/biodiversity/invasive/publications/pubs/pigs-imvs-report.pdf}}</ref> The [[Texas Parks and Wildlife Department]] operates a research facility at [[Kerr Wildlife Management Area]], where they examine feral pig feeding preferences and bait tactics to administer sodium nitrite.<ref>{{cite web |url=https://www.youtube.com/watch?v=GigpxLNbgeg |archive-url=https://ghostarchive.org/varchive/youtube/20211212/GigpxLNbgeg |archive-date=12 December 2021 |url-status=live |title=Hogs Wild – Fighting the Feral Pig Problem | work = Texas Parks and Wildlife |date=21 February 2013|access-date=1 April 2018 |via=[[YouTube]]}}{{cbignore}}</ref>

=== Cancer ===
[[Carcinogenicity]] is the ability or tendency of a chemical to induce tumors, increase their incidence or malignancy, or shorten the time of tumor occurrence.<ref>{{cite web|url=https://www.cancer.org/cancer/cancer-causes/general-info/known-and-probable-human-carcinogens.html|title=Known and Probable Human Carcinogens |website=www.cancer.org |language=en|access-date=28 January 2019}}</ref>

Adding nitrites to meat has been shown to generate known carcinogens such as [[nitrosamine]]s; the [[World Health Organization|World Health Organization (WHO)]] advises that {{convert|50|g|abbr=on}} of "processed meats" a day would raise the risk of getting bowel cancer by 18% over a lifetime, and eating larger amounts raises the risk more. The World Health Organization's review of more than 400 studies concluded, in 2015, that there was sufficient evidence that "processed meats" caused cancer, particularly colon cancer;<ref name="Wilson" /> the WHO's [[International Agency for Research on Cancer|International Agency for Research on Cancer (IARC)]] classified "processed meats" as carcinogenic to humans ([[List of IARC Group 1 carcinogens|Group 1]]); "processed meat" meaning meat that has been transformed through salting, curing, fermentation, smoking, or other processes to enhance flavour or improve preservation.).<ref name=Wilson/><ref>{{cite web |title=IARC Monographs evaluate consumption of red meat and processed meat |url=https://www.iarc.who.int/wp-content/uploads/2018/07/pr240_E.pdf |publisher=International Agency for Research on Cancer |date=26 October 2015 |access-date=14 February 2021 |archive-date=18 January 2021 |archive-url=https://web.archive.org/web/20210118044116/https://www.iarc.who.int/wp-content/uploads/2018/07/pr240_E.pdf|quote=Processed meat was classified as carcinogenic to humans (Group 1), based on sufficient evidence in humans that the consumption of processed meat causes colorectal cancer.}}</ref>

Nitrosamines can be formed during the curing process used to preserve meats, when sodium nitrite-treated meat is cooked, and also from the reaction of nitrite with secondary amines under acidic conditions (such as occurs in the human stomach). Dietary sources of nitrosamines include US cured meats preserved with sodium nitrite as well as the dried salted fish eaten in Japan. In the 1920s, a significant change in US meat curing practices resulted in a 69% decrease in average nitrite content. This event preceded the beginning of a dramatic decline in gastric cancer mortality.<ref>{{cite journal | vauthors = Paik DC, Saborio DV, Oropeza R, Freeman HP | title = The epidemiological enigma of gastric cancer rates in the US: was grandmother's sausage the cause? | journal = International Journal of Epidemiology | volume = 30 | issue = 1 | pages = 181–182 | date = February 2001 | pmid = 11171883 | doi = 10.1093/ije/30.1.181 | doi-access = free}}</ref> Around 1970, it was found that [[ascorbic acid]] (vitamin C), an [[antioxidant]], inhibits nitrosamine formation.<ref>{{cite journal | vauthors = Mackerness CW, Leach SA, Thompson MH, Hill MJ | title = The inhibition of bacterially mediated N-nitrosation by vitamin C: relevance to the inhibition of endogenous N-nitrosation in the achlorhydric stomach | journal = Carcinogenesis | volume = 10 | issue = 2 | pages = 397–399 | date = February 1989 | pmid = 2492212 | doi = 10.1093/carcin/10.2.397}}</ref> Consequently, the addition of at least 550 ppm of ascorbic acid is required in meats manufactured in the United States. Manufacturers sometimes instead use [[erythorbic acid]], a cheaper but equally effective [[isomer]] of ascorbic acid. Additionally, manufacturers may include [[Alpha-Tocopherol|α-tocopherol (vitamin E)]] to further inhibit nitrosamine production. α-Tocopherol, ascorbic acid, and erythorbic acid all inhibit nitrosamine production by their oxidation-reduction properties. Ascorbic acid, for example, forms [[dehydroascorbic acid]] when [[redox|oxidized]], which when in the presence of [[nitrosonium]], a potent nitrosating agent formed from sodium nitrite, reduces the nitrosonium into nitric oxide.<ref>{{cite web |url=http://lpi.oregonstate.edu/publications/research-newsletter|title=Research Newsletter |date=1 July 2014|website=Linus Pauling Institute|access-date=1 April 2018}}</ref> The nitrosonium ion formed in acidic nitrite solutions is commonly<ref>{{cite journal | vauthors = Scanlan RA | title = Formation and occurrence of nitrosamines in food | journal = Cancer Research | volume = 43 | issue = 5 Suppl | pages = 2435s–2440s | date = May 1983 | pmid = 6831466 | id = {{NAID|80001710206}}}}</ref><ref>{{cite book |title=Handbook of Food Analysis |edition=Third |year=2015 |vauthors=Nollet LM, Toldrá F |page=290 |publisher=CRC Press |isbn=978-1-4822-9784-3}}{{page needed|date=February 2021}}</ref> mislabeled [[nitrous anhydride]], an unstable nitrogen oxide that cannot exist in vitro.<ref>{{cite book |doi=10.1016/B978-044451721-0/50002-5 |chapter=Reagents effecting nitrosation |title=Nitrosation Reactions and the Chemistry of Nitric Oxide |year=2004 |vauthors=Williams DL |pages=1–34 |isbn=978-0-444-51721-0}}</ref>

Ingesting nitrite under conditions that result in endogenous [[nitrosation]] has been classified as "probably carcinogenic to humans" by [[International Agency for Research on Cancer]] (IARC).<ref name="monographs.iarc.fr">{{cite web|url=http://monographs.iarc.fr/ENG/Classification/latest_classif.php|title=List of classifications, Volumes 1–116 – IARC Monographs on the Evaluation of Carcinogenic Risks to Humans|date=2010|work=International Agency for Research on Cancer (IARC) – World Health Organization (WHO)|access-date=25 September 2016|archive-date=10 June 2017|archive-url=https://web.archive.org/web/20170610015529/http://monographs.iarc.fr/ENG/Classification/latest_classif.php}}</ref><ref name="ReferenceA">{{cite book |url=http://monographs.iarc.fr/ENG/Monographs/vol94/index.php|title=Ingested Nitrate and Nitrite, and Cyanobacterial Peptide Toxins |volume=94 |series=IARC Monographs on the Evaluation of Carcinogenic Risks to Humans |date=2010 |publisher = International Agency for Research on Cancer (IARC) – World Health Organization (WHO) |access-date=25 September 2016 |isbn=978-92-832-1294-2}}</ref>

Sodium nitrite consumption has also been linked to the triggering of migraines in individuals who already experience them.<ref>{{cite web |url=http://permanent.access.gpo.gov/lps1609/www.fda.gov/fdac/features/1998/398_pain.html |title=Heading Off Migraine Pain |publisher=[[U.S. Food and Drug Administration]] |work=FDA Consumer magazine |year=1998}}</ref>

One study has found a correlation between highly frequent ingestion of meats cured with [[curing salt|pink salt]] and the [[chronic obstructive pulmonary disease|COPD]] form of [[lung disease]].<ref>{{cite news | url = http://www.webmd.com/news/20070417/study-copd-cured-meats-may-be-linked | title = Study: Cured Meats, COPD May Be Linked | vauthors = Hitti M | publisher = WebMD Medical News | date = 17 April 2007}}</ref><ref>{{cite journal | vauthors = Jiang R, Paik DC, Hankinson JL, Barr RG | title = Cured meat consumption, lung function, and chronic obstructive pulmonary disease among United States adults | journal = American Journal of Respiratory and Critical Care Medicine | volume = 175 | issue = 8 | pages = 798–804 | date = April 2007 | pmid = 17255565 | pmc = 1899290 | doi = 10.1164/rccm.200607-969OC}}</ref> The study's researchers suggest that the high amount of nitrites in the meats was responsible; however, the team did not prove the nitrite theory. Additionally, the study does not prove that nitrites or cured meat caused higher rates of COPD, merely a link. The researchers did adjust for many of COPD's risk factors, but they commented they cannot rule out all possible unmeasurable causes or risks for COPD.<ref>{{cite news | url = http://www.webmd.com/news/20070417/study-copd-cured-meats-may-be-linked | title = Study: Cured Meats, COPD May Be Linked | vauthors = Hitti M | publisher = WebMD Medical News | date = 17 April 2007}}</ref><ref>{{cite journal | vauthors = Jiang R, Paik DC, Hankinson JL, Barr RG | title = Cured meat consumption, lung function, and chronic obstructive pulmonary disease among United States adults | journal = American Journal of Respiratory and Critical Care Medicine | volume = 175 | issue = 8 | pages = 798–804 | date = April 2007 | pmid = 17255565 | pmc = 1899290 | doi = 10.1164/rccm.200607-969OC}}</ref>

== Production ==
Industrial production of sodium nitrite follows one of two processes, the reduction of [[nitrate]] salts, or the oxidation of lower [[nitrogen oxide]]s.

One method uses molten [[sodium nitrate]] as the salt, and [[lead]] which is oxidized, while a more modern method uses scrap [[iron]] filings to reduce the nitrate.<ref name=Ullmann/><ref>{{cite journal | vauthors = Hao ZW, Xu XH, Wang DH | title = Reductive denitrification of nitrate by scrap iron filings | journal = Journal of Zhejiang University. Science. B | volume = 6 | issue = 3 | pages = 182–186 | date = March 2005 | pmid = 15682502 | pmc = 1389719 | doi = 10.1631/jzus.2005.B0182}}</ref>

:{{chem2|NaNO3 + Pb → NaNO2 + PbO}}
:{{chem2|NO3- + Fe + 2H+ → NO2- + Fe^{2+} + H2O}}

A more commonly used method involves the general reaction of nitrogen oxides in alkaline aqueous solution, with the addition of a [[Catalysis|catalyst]]. The exact conditions depend on which nitrogen oxides are used, and what the oxidant is, as the conditions need to be carefully controlled to avoid over oxidation of the nitrogen atom.<ref name="Ullmann"/>

:{{chem2|2 NaOH + NO2 + NO → 2 NaNO2 + H2O}}
:{{chem2|2 NaOH + N2O3 → 2 NaNO2 + H2O}}

Sodium nitrite has also been produced by reduction of nitrate salts by exposure to heat, light, ionizing radiation, metals, hydrogen, and electrolytic reduction.<ref>{{cite book |doi=10.1002/0471238961.1915040916151115.a01.pub2 |chapter=Sodium Nitrate and Nitrite |title=Kirk-Othmer Encyclopedia of Chemical Technology |year=2006 |vauthors=Pokorny L, Maturana I, Bortle WH |isbn=978-0-471-23896-6}}</ref>

:{{chem2|NaNO3 + CaSO3 → NaNO2 + CaSO4}}

== Chemical reactions ==
{{main|nitrite|nitrous acid}}
In the laboratory, sodium nitrite can be used to destroy excess [[sodium azide]].<ref>{{cite web |url=http://www.ehs.neu.edu/hazardous_waste/fact_sheets/sodium_azide/ |work=Hazardous Waste Management |title=Sodium Azide |date=March 2003 |publisher=[[Northeastern University]] |archive-url=https://web.archive.org/web/20071104105622/http://www.ehs.neu.edu/hazardous_waste/fact_sheets/sodium_azide/ |archive-date=4 November 2007}}</ref><ref>{{cite book |title=Prudent practices in the laboratory: handling and disposal of chemicals |year=1995 |publisher=[[National Academy Press]] |location=Washington, D.C. |isbn=978-0-309-05229-0 |url=http://books.nap.edu/openbook.php?record_id=4911&page=165 |doi=10.17226/4911}}</ref>
:{{chem2|2 NaN3 + 2 NaNO2 + 4 H+ → 3 N2 + 2 NO + 4 Na+ + 2 H2O}}

Above 330&nbsp;°C sodium nitrite decomposes (in air) to [[sodium oxide]], [[nitric oxide]] and [[nitrogen dioxide]].<ref>{{cite journal |vauthors=Stern KH |title=High Temperature Properties and Decomposition of Inorganic Salts Part 3, Nitrates and Nitrites |journal=Journal of Physical and Chemical Reference Data |date=July 1972 |volume=1 |issue=3 |pages=747–772 |doi=10.1063/1.3253104 |bibcode=1972JPCRD...1..747S |s2cid=95532988}}</ref>
:{{chem2|2 NaNO2 → Na2O + NO + NO2}}

Sodium nitrite can also be used in the production of [[nitrous acid]]:
:{{chem2|2 NaNO2 + H2SO4 → 2 HNO2 + Na2SO4}}

The nitrous acid then, under normal conditions, decomposes:
:{{chem2|2 HNO2 → NO2 + NO + H2O}}

The resulting nitrogen dioxide hydrolyzes to a mixture of nitric and nitrous acids:
:{{chem2|2 NO2 + H2O → HNO3 + HNO2}}

== Isotope labelling <sup>15</sup>N ==
[[File:15n isotope.jpg|class=skin-invert-image|thumb|463x463px|15N isotope enriched NaNO2]]
In organic synthesis isotope enriched sodium nitrite-<sup>15</sup>N can be used instead of normal sodium nitrite as their reactivity is nearly identical in most reactions.

The obtained products carry isotope <sup>15</sup>N and hence [[nitrogen]] [[Nuclear magnetic resonance|NMR]] can be efficiently carried out.<ref>{{cite journal |vauthors=Kazem-Rostami M, Akhmedov NG, Faramarzi S |title=Molecular lambda shape light-driven dual switches: Spectroscopic and computational studies of the photoisomerization of bisazo Tröger base analogs |journal=Journal of Molecular Structure |date=February 2019 |volume=1178 |pages=538–543 |doi=10.1016/j.molstruc.2018.10.071 |bibcode=2019JMoSt1178..538K |s2cid=105312344}}</ref>
{{clear}}

== References ==
{{Reflist}}

=== Sources ===
{{refbegin|30em}}
* {{cite journal | vauthors = Durão C, Pedrosa F, Dinis-Oliveira RJ | title = A fatal case by a suicide kit containing sodium nitrite ordered on the internet | journal = Journal of Forensic and Legal Medicine | volume = 73 | issue = | article-number = 101989 | date = July 2020 | pmid = 32658747 | doi = 10.1016/j.jflm.2020.101989 | ref = {{sfnref|Durão C, ''et al.'', 2020.}} | hdl-access = free | s2cid = 219909654 | hdl = 10400.26/34138}}
* {{cite journal | vauthors = Durão C, Pedrosa F, Dinis-Oliveira RJ | title = Another suicide by sodium nitrite and multiple drugs: an alarming trend for "exit"? | journal = Forensic Science, Medicine, and Pathology | volume = 17 | issue = 2 | pages = 362–366 | date = June 2021 | pmid = 33247411 | doi = 10.1007/s12024-020-00340-2 | ref = {{sfnref|Durão C, ''et al.'', 2021.}} | s2cid = 227180461}}
* {{cite journal | vauthors = Tomsia M, Głaz M, Nowicka J, Szczepański M | title = Sodium nitrite detection in costal cartilage and vitreous humor - Case report of fatal poisoning with sodium nitrite | journal = Journal of Forensic and Legal Medicine | volume = 81 | issue = | article-number = 102186 | date = July 2021 | pmid = 34058704 | doi = 10.1016/j.jflm.2021.102186 | ref = {{sfnref|Tomsia M, ''et al.'', 2021.}} | s2cid = 235268052}}
* {{cite journal | vauthors = McCann SD, Kennedy JM, Tweet MS, Bryant SM | title = Sodium Nitrite Ingestion: an Emerging Trend in Suicide Attempts Shared via Online Communities | journal = The Journal of Emergency Medicine | volume = 60 | issue = 3 | pages = 409–412 | date = March 2021 | pmid = 33712114 | doi = 10.1016/j.jemermed.2020.10.021 | ref = {{sfnref|McCann SD, Kennedy JM, ''et al.'', 2021.}} | s2cid = 232218908}}
* {{cite journal | vauthors = Dean DE, Looman KB, Topmiller RG | title = Fatal methemoglobinemia in three suicidal sodium nitrite poisonings | journal = Journal of Forensic Sciences | volume = 66 | issue = 4 | pages = 1570–1576 | date = July 2021 | pmid = 33598944 | doi = 10.1111/1556-4029.14689 | ref = {{sfnref|Dean DE, ''et al.'', 2021.}} | s2cid = 231952466}}
* {{cite journal | vauthors = Hickey TB, MacNeil JA, Hansmeyer C, Pickup MJ | title = Fatal methemoglobinemia: A case series highlighting a new trend in intentional sodium nitrite or sodium nitrate ingestion as a method of suicide | journal = Forensic Science International | volume = 326 | issue = | article-number = 110907 | date = September 2021 | pmid = 34298207 | doi = 10.1016/j.forsciint.2021.110907 | ref = {{sfnref|Hickey TB, ''et al.'', 2021.}}}}
* {{cite journal | vauthors = Harvey M, Cave G, Chanwai G | title = Fatal methaemoglobinaemia induced by self-poisoning with sodium nitrite | journal = Emergency Medicine Australasia | volume = 22 | issue = 5 | pages = 463–465 | date = October 2010 | pmid = 21040485 | doi = 10.1111/j.1742-6723.2010.01335.x | ref = {{sfnref|Harvey M, ''et al.'', 2010.}} | s2cid = 38780081}}
* {{cite journal | vauthors = McCann SD, Tweet MS, Wahl MS | title = Rising incidence and high mortality in intentional sodium nitrite exposures reported to US poison centers | journal = Clinical Toxicology | volume = 59 | issue = 12 | pages = 1264–1269 | date = December 2021 | pmid = 33787434 | doi = 10.1080/15563650.2021.1905162 | ref = {{sfnref|McCann SD, Tweet MS, Wahl MS, 2021.}} | s2cid = 232431594 | doi-access = free}}
* {{cite journal | vauthors = Sedhai YR, Atreya A, Basnyat S, Phuyal P, Pokhrel S | title = The use of sodium nitrite for deliberate self-harm, and the online suicide market: Should we care? | journal = The Medico-Legal Journal | volume = 90 | issue = 2 | pages = 79–80 | date = June 2022 | pmid = 33906496 | doi = 10.1177/0025817221998119 | ref = {{sfnref|Sedhai YR, ''et al.'', 2022.}} | s2cid = 233429578}}
* {{cite journal | vauthors = Mudan A, Repplinger D, Lebin J, Lewis J, Vohra R, Smollin C | title = Severe Methemoglobinemia and Death From Intentional Sodium Nitrite Ingestions | journal = The Journal of Emergency Medicine | volume = 59 | issue = 3 | pages = e85–e88 | date = September 2020 | pmid = 32713620 | doi = 10.1016/j.jemermed.2020.06.031 | ref = {{sfnref|Mudan A, ''et al.'', 2020.}} | s2cid = 220797852}}
{{refend}}

== Further reading ==
{{refbegin}}
* {{cite journal | title = Toxicology and carcinogenesis studies of sodium nitrite (CAS NO. 7632-00-0) in F344/N rats and B6C3F1 mice (drinking water studies) | journal = National Toxicology Program Technical Report Series | volume = 495 | pages = 7–273 | date = May 2001 | pmid = 12563346 | url = https://ntp.niehs.nih.gov/publications/reports/tr/tr495 | author1 = National Toxicology Program}}
{{refend}}

== External links ==
* {{cite web | title = Sodium nitrite | url = http://www.inchem.org/documents/icsc/icsc/eics1120.htm | work = International Chemical Safety Card | id = 1120 | publisher = IPCS INCHEM}}
* {{cite web | vauthors = Epley RJ, Addis PB, Warthesen JJ | date = 2011 | url = http://www.extension.umn.edu/distribution/nutrition/DJ0974.html | archive-url = https://web.archive.org/web/20110101140455/http://www.extension.umn.edu/distribution/nutrition/DJ0974.html | title = Nitrite in Meat | archive-date = 1 January 2011 | work = University of Minnesota}}

{{Antidotes}}
{{Sodium compounds}}
{{Nitrites}}
{{Portal bar|Medicine}}

{{DEFAULTSORT:Sodium Nitrite}}
[[Category:Antidotes]]
[[Category:Color fixers]]
[[Category:Corrosion inhibitors]]
[[Category:Curing agents]]
[[Category:E-number additives]]
[[Category:Food additives]]
[[Category:Garde manger]]
[[Category:Nitrites]]
[[Category:Oxidizing agents]]
[[Category:Preservatives]]
[[Category:Sodium compounds]]
[[Category:World Health Organization essential medicines]]
[[Category:Orphan drugs]]
[[Category:Multiple Chemboxes|X]]
[[Category:Suicide by poison]]