Sodium Nitrite

I got this from Wikipedia in February 2017 for learning purposes.

1. Sodiumnitrite
Not to be confused withsodium nitrate,sodium nitride,
ornitratine.
“E250” redirects here. For the mobile phone, see
Samsung SGH-E250.
Sodium nitriteis theinorganic compoundwith the
chemical formulaNaNO2. It is a white to slightly yellow-
ish crystalline powder that is very soluble inwaterand
ishygroscopic. It is a useful precursor to a variety of
organic compounds, such as pharmaceuticals, dyes, and
pesticides, but it is probably best known as a food addi-
tive to preventbotulism.
It is on theWorld Health Organization’s List of Essential
Medicines, the most important medications needed in a
basichealth system.
[2]
1 Uses
1.1 Industrial chemistry
The main use of sodium nitrite is for the industrial pro-
duction of organonitrogen compounds. It is a reagent for
conversion ofaminesintodiazocompounds, which are
key precursors to many dyes, such asdiazo dyes.Nitroso
compoundsare produced from nitrites. These are used in
the rubber industry.
[3]
Other applications include uses inphotography. It may
also be used as anelectrolyteinelectrochemical grinding
manufacturing processes, typically diluted to about 10%
concentration in water. It is used in a variety of metallur-
gical applications, for phosphatizing and detinning.
Sodium nitrite is an effectivecorrosion inhibitorand is
used as an additive in industrial greases,
[4]
as an aqueous
solution in closed loop cooling systems, and in a molten
state as a heat transfer medium.
[5]
1.2 Medicine
Main article:Sodium nitrite (medical use)
Sodium nitrite is used together withsodium thiosulfateto
treatcyanide poisoning.
[6]
It is in the section "antidotes and other substances used
in poisonings" of theWorld Health Organization’s List
of Essential Medicines, the most important medications
needed in a basichealth system.
[2]
1.3 Food additive
In the early 1900s, irregularcuringwas commonplace.
This led to further research surrounding the use of sodium
nitrite as anadditiveinfood, standardizing the amount
present in foods to minimize the amount needed while
maximizing itsfood additiverole.
[7]
Through this re-
search, sodium nitrite has been found to inhibit growth
of disease-causingmicroorganisms; give taste and color
to the meat; and inhibit lipid oxidation that leads to
rancidity.
[7]
The ability of sodium nitrite to address the
above-mentioned issues has led to production ofmeat
with improvedfood safety, extended storage life and im-
proving desirable color/taste.
[7]
It has theE numberE250.
Potassium nitrite(E249) is used in the same way. It is
approved for usage in theEU,
[8][9]
USA
[10]
and Australia
and New Zealand.
[11]
1.3.1 Inhibition of microbial growth
Sodium nitrite is well known for its role in inhibiting
the growth ofClostridium botulinumspores in refriger-
ated meats.
[12]
The mechanism for this activity results
from the inhibition ofiron-sulfur clustersessential to en-
ergy metabolism ofClostridium botulinum.
[12]
However,
sodium nitrite has had varying degrees of effectiveness
for controlling growth of other spoilage or disease caus-
ingmicroorganisms.
[7]
Even though the inhibitory mech-
anisms for sodium nitrite are not well known, its effec-
tiveness depends on several factors including residual ni-
trite level,pH, salt concentration, reductants present and
ironcontent.
[13]
Furthermore, the type ofbacteriaalso
affects sodium nitrites effectiveness.
[13]
It is generally
agreed upon that sodium nitrite is not considered effec-
tive for controllinggram-negativeenteric pathogens such
asSalmonellaandEscherichia coli.
[13]
1.3.2 Taste and color
Theappearanceandtasteof meat is an important com-
ponent of consumer acceptance.
[7]
Sodium nitrite is re-
sponsible for the desirable red color (or shaded pink)
of meat.
[7]
Very little nitrite is needed to induce this
change.
[7]
It has been reported that as little as 2 to 14
parts per million (ppm) is needed to induce this desirable
colorchange.
[13]
However, to extend the lifespan of this
1

2. 2 2 TOXICITY
color change, significantly higher levels are needed.
[13]
The mechanism responsible for this color change is the
formation of nitrosylating agents bynitrite, which has
the ability to transfernitric oxidethat subsequently re-
acts withmyoglobinto produce thecuredmeat color.
[13]
The unique taste associated with cured meat is also af-
fected by the addition of sodium nitrite.
[7]
However, the
mechanism underlying this change in taste is still not fully
understood.
[13]
1.3.3 Inhibition of lipid oxidation
Sodium nitrite is also able to effectively delay the de-
velopment ofoxidativerancidity.
[13]
Lipid oxidationis
considered to be a major reason for the deterioration
of quality of meat products (rancidityand unappetiz-
ing flavors).
[13]
Sodium nitrite acts as anantioxidantin
a mechanism similar to the one responsible for the col-
oring affect.
[13]
Nitrite reacts withhemeproteins and
metal ions, neutralizingfree radicalsbynitric oxide(one
of its byproducts).
[13]
Neutralization of thesefree radi-
calsterminates the cycle oflipid oxidationthat leads to
rancidity.
[13]
2 Toxicity
While this chemical will prevent the growth of bacteria,
it can be toxic in high amounts for animals and humans.
Sodium nitrite’sLD50in rats is 180 mg/kg and its human
LDLₒis 71 mg/kg, meaning a 65 kg person would likely
have to consume at least 4.6gto result in death.
[14]
To
prevent toxicity, sodium nitrite (blended with salt) sold
as a food additive is dyed bright pink to avoid mistak-
ing it for plain salt or sugar. Nitrites are not naturally
occurring in vegetables in significant quantities.
[15]
How-
ever, nitrates are found in commercially available veg-
etables and a study in an intensive agricultural area in
northern Portugal found residual nitrate levels in 34 veg-
etable samples, including different varieties of cabbage,
lettuce, spinach, parsley and turnips ranged between 54
and 2440 mg/kg, e.g. curly kale (302.0 mg/kg) and green
cauliflower (64 mg/kg).
[16][17]
Boiling vegetables lowers
nitrate but not nitrite.
[16]
Fresh meat contains 0.4–0.5
mg/kg nitrite and 4–7 mg/kg of nitrate (10–30 mg/kg ni-
trate in cured meats).
[15]
The presence of nitrite in animal
tissue is a consequence of metabolism ofnitric oxide, an
important neurotransmitter.
[18]
Nitric oxide can be cre-
atedde novofromnitric oxide synthaseutilizingarginine
or from ingestednitrateornitrite.
[19]
2.1 Humane toxin for feral hog/wild boar
control
Because of sodium nitrite’s high level of toxicity to swine
(Sus scrofa) it is now being developed in Australia to con-
trol feral pigs andwild boar.
[20][21]
The sodium nitrite in-
ducesmethemoglobinemiain 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 hu-
mane manner after first being rendered unconscious.
[22]
TheTexas Parks and Wildlife Departmentoperates a re-
search facility atKerr Wildlife Management Area, where
they examine feral pig feeding preferences and bait tac-
tics to administer sodium nitrite.
[23]
2.2 Nitrosamines
A principal concern about sodium nitrite is the formation
ofcarcinogenicnitrosaminesin meats containing sodium
nitrite when meat is charred or overcooked. Such car-
cinogenic nitrosamines can also be formed from the re-
action of nitrite with secondary amines under acidic con-
ditions (such as occurs in the human stomach) as well as
during thecuring processused to preserve meats. Di-
etary 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 begin-
ning of a dramatic decline in gastric cancer mortality.
[24]
About 1970, it was found thatascorbic acid(vitamin C),
anantioxidant, inhibits nitrosamine formation.
[25]
Con-
sequently, the addition of at least 550 ppm of ascor-
bic acid is required in meats manufactured in the United
States. Manufacturers sometimes instead useerythorbic
acid, a cheaper but equally effectiveisomerof ascor-
bic acid. Additionally, manufacturers may includeα-
tocopherol (vitamin E)to further inhibit nitrosamine pro-
duction. α-Tocopherol, ascorbic acid, and erythorbic
acid all inhibit nitrosamine production by their oxidation-
reduction properties. Ascorbic acid, for example, forms
dehydroascorbic acidwhenoxidized, which when in
the presence ofnitrosonium, a potent nitrosating agent
formed from sodium nitrite, reduces the nitrosonium into
nitric oxide.
[26]
The nitrosonium ion formed in acidic ni-
trite solutions is commonly
[27][28]
mislabeled nitrous an-
hydride, an unstable nitrogen oxide that cannot exist in
vitro.
[29]
Nitrate ornitrite(ingested) under conditions that result
in endogenousnitrosationhas been classified as “proba-
bly carcinogenic to humans” byInternational Agency for
Research on Cancer(IARC).
[30][31]
Sodium nitrite consumption has also been linked to the
triggering of migraines in individuals who already suffer
from them.
[32]
One study has found a correlation between highly fre-
quent ingestion of meats cured withpink saltand the
COPDform oflung disease. The study’s researchers sug-
gest that the high amount of nitrites in the meats was re-
sponsible; however, the team did not prove the nitrite the-
ory. Additionally, the study does not prove that nitrites or

3. 3
cured meat caused higher rates of COPD, merely a link.
The researchers did adjust for many of COPD’s risk fac-
tors, but they commented they cannot rule out all possible
unmeasurable causes or risks for COPD.
[33][34]
3 Mechanism of action
Carcinogenic nitrosamines are formed whenaminesthat
occur naturally in food react with sodium nitrite found in
cured meat products.
R2NH (amines) + NaNO2(sodium nitrite) → R2N–N=O
(nitrosamine)
In the presence of acid (such as in the stomach) or heat
(such as via cooking), nitrosamines are converted to
diazonium ions.
R2N–N=O (nitrosamine) + (acid or heat) → R–N+
2 (diazonium ion)
Certain nitrosamines such asN-nitrosodimethylamine
[35]
andN-nitrosopyrrolidine
[36]
form carbocations that react
with biologicalnucleophiles(such as DNA or an enzyme)
in the cell.
R–N+
2 (diazonium ion) → R
+
(carbocation) + N2(leaving
group) + Nu (biological nucleophiles) → R–Nu
If thisnucleophilic substitutionreaction occurs at a cru-
cial site in a biomolecule, it can disrupt normal cell func-
tions, leading to cancer orcell death.
4 Production
The salt is prepared by treating sodium hydroxide with
mixtures ofnitrogen dioxideandnitric oxide:
2 NaOH + NO2+ NO → 2 NaNO2+ H2O
The conversion is sensitive to the presence of oxygen,
which can lead to varying amounts ofsodium nitrate.
In former times, sodium nitrite was prepared by reduction
of sodium nitrate with various metals.
[3][37]
5 Chemical reactions
In the laboratory, sodium nitrite can be used to destroy
excesssodium azide.
[38][39]
2 NaN3+ 2 NaNO2+ 2 H
+
→ 3 N2+ 2 NO + 2 Na
+
+
2 H2O
Above 330 °C sodium nitrite decomposes (in air) to
sodium oxide,nitric oxideandnitrogen dioxide.
[40]
2 NaNO2→ Na2O + NO + NO2
Sodium nitrite can also be used in the production of
nitrous acidviasulfuric acid. This reaction first yields
nitrous acidandsodium sulfate:
2 NaNO
2 + H
2SO
4 → 2 HNO
2 + Na
2SO
4
The nitrous acid then, under normal conditions, decom-
poses:
2 HNO
2 → NO
2 + NO + H
2O
The nitrogen dioxide of the prior decomposition is then
routed through acondensororfractional distillation ap-
paratusto react with water and yield nitric acid:
2 NO
2 + H
2O → HNO
3 + HNO
2
6 References
[1]Zumdahl, Steven S. (2009).Chemical Principles(6th ed.).
Houghton Mifflin Company. p. A23.ISBN0-618-
94690-X.
[2]“WHO Model List of EssentialMedicines”(PDF).World
Health Organization. April 2015. Retrieved 25 Septem-
ber 2016.
[3]Wolfgang Laue, Michael Thiemann, Erich Scheibler, Karl
Wilhelm Wiegand “Nitrates and Nitrites” inUllmann’s
Encyclopedia of Industrial Chemistry, 2002, Wiley-VCH,
Weinheim.doi:10.1002/14356007.a17_265. Article On-
line Posting Date: 15 June 2000
[4]Krakhmalev, S. I.; Vorotnikova, V. A.; Ten, N. V.;
Taranova, N. V. (1984). “Determination of sodium
nitrite in complex sodium grease”.Chemistry And
Technology Of Fuels And Oils.20(12): 612–613.
doi:10.1007/BF00726438.
[5]“Sodium Nitrite”. General Chemical. Retrieved 2012-09-
28.

4. 4 6 REFERENCES
[6]WHO Model Formulary 2008(PDF). World Health Orga-
nization. 2009. p. 65-66.ISBN9789241547659. Re-
trieved 8 January 2017.
[7]Sindelar, Jeffrey; Milkowski, Andrew (March 2012).
“Human safety controversies surrounding nitrate and
nitrite in the diet”.Nitric Oxide.26: 259–266.
doi:10.1016/j.niox.2012.03.011.
[8]UK Food Standards Agency:“Current EU approved addi-
tives and their E Numbers”. Retrieved 27 October 2011.
[9]http://ec.europa.eu/food/fs/sc/scf/reports/scf_reports_
38.pdf
[10]US Food and Drug Administration:“Listing of Food Ad-
ditives Status Part II”. Retrieved 27 October 2011.
[11]Australia New Zealand Food Standards Code“Standard
1.2.4 – Labelling of ingredients”. Retrieved 27 October
2011.
[12]Milkowski, Andrew; Garg, Harsha; Couglin, James;
Bryan, Nathan (January 2010). “Nutritional epidemiol-
ogy in the context of nitric oxide biology: Risk-Benefit
evaluation for dietary nitrite and nitrate”.Nitric Oxide.22
(2): 110–119.doi:10.1016/j.niox.2009.08.004.PMID
19748594.
[13]Sindelar, Jeffrey; Milkowski, Andrew (November 2011).
“Sodium Nitrite in Processed Meat and Poultry Meats: A
Review of Curing and Examining the Risk/Benefit of Its
Use”(PDF).American Meat Science Association.3: 1–14.
[14]http://msds.chem.ox.ac.uk/SO/sodium_nitrite.html
[15]Dennis, M. J.; Wilson, L. A. (2003). “Nitrates and
Nitrites”.Encyclopedia of Food Sciences and Nutrition.
p. 4136.doi:10.1016/B0-12-227055-X/00830-0.ISBN
978-0-12-227055-0.
[16]Leszczyńska, Teresa; Filipiak-Florkiewicz, Agnieszka;
Cieślik, Ewa; Sikora, ElżBieta; Pisulewski, Paweł M.
(2009). “Effects of some processing methods on nitrate
and nitrite changes in cruciferous vegetables”.Journal
of Food Composition and Analysis.22(4): 315–321.
doi:10.1016/j.jfca.2008.10.025.
[17]Correia, Manuela; Barroso, Ângela; Barroso, M. Fá-
tima; Soares, Débora; Oliveira, M. B. P. P.; Delerue-
Matos, Cristina (2010). “Contribution of different
vegetable types to exogenous nitrate and nitrite ex-
posure”.Food Chemistry.120(4): 960–966.
doi:10.1016/j.foodchem.2009.11.030.
[18]Meulemans, A.; Delsenne, F. (1994). “Measurement of
nitrite and nitrate levels in biological samples by capillary
electrophoresis”.Journal of Chromatography B.660(2):
401–404.doi:10.1016/0378-4347(94)00310-6.
[19]Southan, G; Srinivasan, A (1998). “Nitrogen Oxides and
Hydroxyguanidines: Formation of Donors of Nitric and
Nitrous Oxides and Possible Relevance to Nitrous Oxide
Formation by Nitric Oxide Synthase”.Nitric Oxide.2(4):
270–86.doi:10.1006/niox.1998.0187.PMID9851368.
[20]Lapidge, Steven; Wishart, J.; Smith, M.; Staples, L.
(2009). “Is America Ready for a Humane Feral Pig Toxi-
cant?".Proceedings of the 13th Wildlife Damage Manage-
ment Conference: 49–59.
[21]Cowled, B. D.; Lapidge, S. J.; Humphrys, S.; Staples, L.
(2008).“Nitrite Salts as Poisons in Baits for Omnivores”.
International Patent WO/2008/104028.
[22]Porter, S.; Kuchel, T. (2010).Assessing the humaness and
efficacy of a new feral pig bait in domestic pigs. Study
PC0409(PDF). Canberra, South Australia: Veterinary
Services Division, Institute of Medical and Veterinary
Science. p. 11.
[23]https://www.youtube.com/watch?v=GigpxLNbgeg&
spfreload=1
[24]“The epidemiological enigma of gastric cancer rates in the
US: was grandmother’s sausage the cause?".International
Journal of Epidemiology. 2000.
[25]Mackerness, C. W.; Leach, S. A.; Thompson, M.
H.; Hill, M. J. (1989).“The inhibition of bacte-
rially mediatedN-nitrosation by vitamin C: relevance
to the inhibition of endogenousN-nitrosation in the
achlorhydric stomach”.Carcinogenesis.10(2): 397–9.
doi:10.1093/carcin/10.2.397.PMID2492212.
[26]Nitrosamines and Cancer by Richard A. Scanlan, Ph.D.
[27]Cancer Res.43(5 Suppl): 2435s–2440s. May 1983.
Missing or empty |title= (help)
[28]Nollet, Toldra, D (2015).Handbook of Food Analysis
(Third ed.). p. 290.ISBN9781482297843.
[29]Williams, D (2004). “Reagents effecting nitrosation”.Ni-
trosation Reactions and the Chemistry of Nitric Oxide. p.
1.doi:10.1016/B978-044451721-0/50002-5.ISBN978-
0-444-51721-0.
[30]“List of classifications, Volumes 1–116 - IARC Mono-
graphs on the Evaluation of Carcinogenic Risks to Hu-
mans”.International Agency for Research on Cancer
(IARC) - World Health Organization (WHO). 2010. Re-
trieved 25 September 2016.
[31]“VOLUME 94 - Ingested Nitrate and Nitrite, and
Cyanobacterial Peptide Toxins - IARC Monographs on
the Evaluation of Carcinogenic Risks to Humans”.Inter-
national Agency for Research on Cancer (IARC) - World
Health Organization (WHO). 2010. Retrieved 25 Septem-
ber 2016.
[32]“Heading Off Migraine Pain”.FDA Consumer magazine.
U.S. Food and Drug Administration. 1998.
[33]Hitti, Miranda (17 April 2007).“Study: Cured Meats,
COPD May Be Linked”. WebMD Medical News.
[34]Jiang, R.; Paik, D. C.; Hankinson, J. L.; Barr,
R. G. (2007).“Cured Meat Consumption, Lung
Function, and Chronic Obstructive Pulmonary Dis-
ease among United States Adults”.American Jour-
nal of Respiratory and Critical Care Medicine.175
(8): 798–804.doi:10.1164/rccm.200607-969OC.PMC
1899290 .PMID17255565.

5. 5
[35]Najm, Issam; Trussell, R. Rhodes (February 2001).
“NDMA Formation in Water and Wastewater”.Journal
AWWA.93(2): 92–99.
[36]Bills, Donald D.; Hildrum, Kjell I.; Scanlan, Richard
A.; Libbey, Leonard M. (May 1973). “Potential pre-
cursors ofN-nitrosopyrrolidine in bacon and other fried
foods”.J. Agric. Food Chem.21(5): 876–7.
doi:10.1021/jf60189a029.PMID4739004.
[37]Hao, Zhi-wei; Xu, Xin-hua; Wang, Da-hui (March 2005).
“Reductive denitrification of nitrate by scrap iron filings”.
Journal of Zhejiang University SCIENCE.6B(3): 182–
186.doi:10.1631/jzus.2005.B0182.
[38]“Sodium Azide”.Hazardous Waste Management.
Northeastern University. March 2003.
[39]Committee on Prudent Practices for Handling, Stor-
age, and Disposal of Chemicals in Laboratories, Board
on Chemical Sciences and Technology, Commission on
Physical Sciences, Mathematics, and Applications, Na-
tional Research Council (1995).Prudent practices in the
laboratory: handling and disposal of chemicals. Washing-
ton, D.C.:National Academy Press.ISBN0-309-05229-
7.
[40]Stern, Kurt H. (1972).“High Temperature Properties and
Decomposition of Inorganic Salts; Part 3. Nitrates and
Nitrites”(PDF).J. Phys. Chem. US Naval Research Lab-
oratory.1(3): 750–751.doi:10.1063/1.3253104. Re-
trieved 15 March 2014.
7 External links
-ATSDR – Case Studies in Environmental Medicine
– Nitrate/Nitrite ToxicityU.S.Department of
Health and Human Services(public domain)
-International Chemical Safety Card 1120.
-National Center for Home Food Preservation Ni-
trates and Nitrites.
-TR-495: Toxicology and Carcinogenesis Studies
of Sodium Nitrite (CAS NO. 7632-00-0) Drinking
Water Studies in F344/N Rats and B6C3F1Mice.
-Nitrite in Meat

6. 6 8 TEXT AND IMAGE SOURCES, CONTRIBUTORS, AND LICENSES
8 Text and image sources, contributors, and licenses
8.1 Text
-Sodium nitriteSource:https://en.wikipedia.org/wiki/Sodium_nitrite?oldid=764697480Contributors:Karada, Tristanb, Malbi, Ike9898,
Dysprosia, Calden, Riddley, TomDowden, Giftlite, Duncharris, Eequor, D3, Andycjp, Beland, Onco p53, Iantresman, Clemwang, Rich
Farmbrough, Grillo7, Kjoonlee, CanisRufus, Smalljim, Davidruben, Mikemsd, Arcadian, Hooperbloob, Nicolasbock, Keenan Pepper,
ABCD, Fasten, RJFJR, Vuo, Sivar, DePiep, Rjwilmsi, Hermione1980, Titoxd, FlaBot, RexNL, Physchim62, Antilived, WriterHound,
YurikBot, Hairy Dude, Farnkerl, Gaius Cornelius, Shaddack, E rulez, RyanJones, 2over0, Wizard IT, SmackBot, Anastrophe, Edgar181,
Apers0n, Fueled~enwiki, Eug, Dkechag, Darnoconrad, MalafayaBot, Uthbrian, Nick Levine, Rfwoolf, Homestarmy, Smokefoot, DMacks,
A5b, Kukini, Beetstra, Maelor, Thricecube, Tawkerbot2, Fvasconcellos, W guice, Cybernetic, Dr Zak, Cydebot, Robinatron, Rifleman
82, Bazzargh, Christian75, Trev M, GentlemanGhost, Headbomb, Dikteren, OSX, Mrs smartygirl, JAnDbot, Instinct, Arch dude, Igodard,
Ramurf, VoABot II, J.P.Lon, Smash1gordon, Philg88, ChemNerd, J.delanoy, Captain panda, 4johnny, DarkFalls, Cosmolux, DadaNeem,
Thioxane, Bcostley, MartinBotIII, Idioma-bot, Vmaldia, Deor, Shiggity, Philip Trueman, TXiKiBoT, JhsBot, Tanner-Christopher, Envi-
roboy, Doc James, AlleborgoBot, Logan, Wikiscottcha, Mayfare, Caltas, Yintan, Chem-awb, ClueBot, Boing! said Zebedee, Shjacks45,
Shinkolobwe, Plasmic Physics, DumZiBoT, Gardenparty, PSimeon, Dthomsen8, Addbot, C6541, DOI bot, EjsBot, Woelen, H92Bot,
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Riventree, ДмитрОст, D'ohBot, DivineAlpha, Citation bot 1, I dream of horses, Mutinus, Babahu, MastiBot, HowardJWilk, SpaceFlight89,
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virBot, Sxoa, TexBrazos, Bobkart, PsychoHipE, Dcirovic, ZéroBot, Chemicalinterest, Alexsmith44, Donner60, Orange Suede Sofa, Chuis-
pastonBot, Whoop whoop pull up, Louisajb, ClueBot NG, Szfjozsef, Rosommer, Rycecube57, Snotbot, Kilterwind, Helpful Pixie Bot,
JohnSRoberts99, Titodutta, Simonnem, Carlstak, Newmanrs, Glacialfox, BattyBot, LegacyOfValor, Maple leaf eh, Gareth CHEBI, Jes-
salynShamess, Francesca Cattaneo, Mysterious Whisper, AAMCasilli, Sriharsh1234, Project Osprey, ChaseAm, Stamptrader, JaconaFrere,
Monkbot, Deren holmes chu, Matyson, Qwertyxp2000, Crystallizedcarbon, Konabruce01, VexorAbVikipædia, Adam9007, TerpeneOtto,
Brock6988 and Anonymous: 164
8.2 Images
-File:Hazard_N.svgSource:https://upload.wikimedia.org/wikipedia/commons/6/6a/Hazard_N.svgLicense:Public domainContributors:
Converted from EPS file athttp://forum.cptec.org/index.php?showtopic=368Original artist:See historic
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tributors:Own work using: ChemDraw 8.0Original artist:Eschenmoser
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tors:Derived fromFile:Sodium-hydride-monomer-CRC-MW-3D-balls.png.Original artist:Ben MillsandJynto
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