E250 - Sodium nitrite, properties uses and risks

E250 (Sodium nitrite) is a chemical compound, an inorganic sodium salt ion and a physiological derivative of nitric oxide to which it can be bioactivated.  It is very soluble in water and liquid ammonia, stable under anaerobic conditions. Slightly soluble in ether, ethanol, methanol and other organic solvents. It reacts with oxygen to form sodium nitrate when exposed to air.

The name defines the structure of the molecule

• "Sodium". It's an alkali metal, symbol Na, with atomic number 11. It's an essential element for life and plays a key role in regulating blood pressure and plasma volume.
• "Nitrite". Refers to the salt or ester of nitrous acid and has the chemical formula NO2-. Nitrites are used as food preservatives and as antimicrobial agents.

Description of the raw materials used in its production:

• Nitrogen Oxides (NO and NO₂) - These gases are generated during high-temperature combustion operations.
• Sodium Hydroxide (NaOH) or Sodium Carbonate (Na₂CO₃) - These alkaline reagents react with nitrogen oxides to form sodium nitrite.

Industrial chemical synthesis of Sodium Nitrite, step by step:

• Production of Nitrogen Oxides - During high-temperature combustion, nitrogen and oxygen from the air react to form nitrogen oxides (NO and NO₂).
• Absorption of Nitrogen Oxides - The nitrogen oxides are absorbed into an aqueous solution of sodium hydroxide (NaOH) or sodium carbonate (Na₂CO₃). This reaction yields sodium nitrite (NaNO₂):
• Crystallization - The sodium nitrite solution is cooled to allow for the crystallization of sodium nitrite.
• Isolation and Filtration - The crystals of sodium nitrite are separated from the solution by filtration.
• Drying - The filtered crystals are dried to remove residual water.

It occurs as a white or yellowish crystalline powder.

What it is used for and where

It is used in medicine, food, fertiliser, fixative in dyes, biological insecticide, antifreeze, raw material in the production of caffeine and saccharin, corrosion inhibitor for steel, bleaching agent for silk and linen, heat treatment agent for metals, bleaching, electroplating.

Chromatography: to determine mercury, potassium and chlorate. Nitrification and diazotization reagent (temporary generation of sodium nitrite and hydrochloric acid). Soil analysis.  Serum bilirubin measured in liver function test.

Food

Ingredient listed in the European food additives list as E250, preservative.

Nitrites and nitrates are inserted into processed meat to give it a characteristic colour and preserve it. In the 1800s saltpetre was used to preserve meat, but it was in the 1950s and 1960s that nitrites were used regularly. Sodium salts or potassium salts were also used as alternatives.

The use of sodium nitrite is now permitted but at concentrations strictly laid down in European legislation on food additives (Regulation (EC) No 1333/2008). Sodium nitrite is labelled with the number E250 in the list of European additives as a preservative. It is subject to an Acceptable Daily Intake (ADI) of 0-0.07 mg/kg body weight per day by the SCF (1997) and JECFA (2002).

Sodium nitrite is a common curing agent that performs its protective action against lipid oxidation, however this study notes that while there is a rapid expansion of meat products using natural nitrate derivatives, there is a fundamental lack of understanding regarding the safety and chemical implications of curing agents, whether derived from synthetic or natural sources. A high intake of nitrites poses a risk to consumers due to vasodilatory effects and the production of carcinogenic nitrosamines (1). Meat products treated with sodium nitrite may be contaminated with carcinogenic N-nitrosamines depending on the method of processing (ageing, maturing, fermentation, smoking, heat treatment and storage) (2).

A report by the World Cancer Research Fund in 2007 emphasised the importance of limiting red meat intake and avoiding processed meat as compelling evidence points to an association between processed red meat and cancer (3) and this study, referring to a workshop held in Oslo, Norway in November 2013 where the health aspect of red and processed meat was discussed, draws attention to an unbalanced red meat-dominated diet that may increase the risk of colorectal cancer (4).

Prolonged intake of large amounts of nitrite is associated with an increased risk of developing stomach cancer and oesophageal cancer. Foods containing potassium nitrite (E249), sodium nitrite (E250) and potassium nitrate (E252) should therefore be avoided or greatly reduced, especially in canned meat, sausages and processed meats (5).

In 2017, the Panel on Food Additives and Nutrient Sources added to Food (ANS) provided a scientific opinion on the safety of sodium nitrite concluding that there is evidence to attribute NDMA (n-nitrosodimethylamine) a link to colorectal cancers (6).

Cosmetics

Anticorrosive. It is a restricted ingredient III/17 as a relevant item in the Annexes of the European Cosmetics Regulation 1223/2009. Maximum concentration in the ready-for-use preparation 0.2%. Do not use with secondary and/or tertiary amines or other nitrosamine-forming substances. 

Commercial applications 

Preservative in Food Products. Sodium nitrite is used as a preservative, especially in processed meats like sausages, to prevent the growth of bacteria.

Coloring Agent in Foods. It acts as a color fixative in processed meats, helping to maintain an appealing red color.

Corrosion Inhibitor. Used in engine cooling solutions and other industrial applications to prevent corrosion of metals.

Reagent in Chemical Analysis. Used as a reagent in various chemical tests to analyze and determine the presence of specific compounds.

Rubber Production. Used in the production of rubber as a maturing agent to improve strength and processing properties.

Sodium nitrite studies

Typical optimal commercial product characteristics Sodium nitrite

Appearance	Colorless or yellow crystal
Content of sodium nitrite %	≥98.5
Boiling Point	320 °C
Melting Point	271 °C(lit.)
Density	1.29 g/mL at 25 °C
PSA	52.49000
LogP	0.25060
Water Solubility	820 g/L (20 ºC)
Water insoluble matter	≤0.05%
Sodium nitrate	≤0.8%
Chloride	≤50ppm
Moisture %	≤2.0
Storage	2-8°C
Safety

• Molecular Formula : NNaO₂
• Molecular Weight : 68.995
• Exact Mass   68.982674
• CAS : 7632-00-0
• UNII M0KG633D4F
• EC Number   231-555-9
• DSSTox Substance ID DTXSID0020941
• IUPAC  sodium;nitrite
• InChI=1S/HNO2.Na/c2-1-3;/h(H,2,3);/q;+1/p-1  
• InChl Key      LPXPTNMVRIOKMN-UHFFFAOYSA-M
• SMILES   N(=O)[O-].[Na+]
• MDL number  MFCD00011118
• PubChem Substance ID 329752451
• ChEBI  78870
• ICSC    1120
• NSC   77391
• RTECS   RA1225000
• UN   1500   3287

Sinonimi :

• Nitrous acid, sodium salt
• Nitrite, Sodium

References_____________________________________________________________________

(1) Rivera N, Bunning M, Martin J. Uncured-Labeled Meat Products Produced Using Plant-Derived Nitrates and Nitrites: Chemistry, Safety, and Regulatory Considerations. J Agric Food Chem. 2019 Jul 24;67(29):8074-8084. doi: 10.1021/acs.jafc.9b01826. 

Abstract. Consumers often malign conventional curing agents while concomitantly accepting the natural forms of the same constituents in numerous food products. This paradox ostensibly exceeds all other food-related controversies to date and likely contributes to the rapid expansion of meat products that utilize natural nitrate derivatives. While there is high demand for these products, a fundamental lack of understanding regarding the safety and chemical implications of curing agents, whether derived from synthetic or natural sources, continues to persist. This manuscript elucidates the variations among curing preparations with particular emphasis pertaining to the associated safety, chemical, and regulatory ramifications encompassing these product categories.

(3) De Mey E, De Maere H, Paelinck H, Fraeye I. Volatile N-nitrosamines in meat products: Potential precursors, influence of processing, and mitigation strategies. Crit Rev Food Sci Nutr. 2017 Sep 2;57(13):2909-2923. doi: 10.1080/10408398.2015.1078769.

Abstract. Meat products can be contaminated with carcinogenic N-nitrosamines, which is ascribed to the reaction between a nitrosating agent, originating from nitrite or smoke, and a secondary amine, derived from protein and lipid degradation. Although in model systems it is demonstrated that many amine containing compounds can be converted to N-nitrosamines, the yield is dependent of reaction conditions (e.g., low pH and high temperature). In this article, the influence of the composition of the meat products (e.g., pH, aw, spices) and processing (e.g., ageing, ripening, fermentation, smoking, heat treatment and storage) on the presence and availability of the amine precursors and the N-nitrosamine formation mechanism is discussed. In addition, this article explores the current N-nitrosamine mitigation strategies in order to obtain healthier and more natural meat products.

(3) Demeyer D, Honikel K, De Smet S. The World Cancer Research Fund report 2007: A challenge for the meat processing industry. Meat Sci. 2008 Dec;80(4):953-9. doi: 10.1016/j.meatsci.2008.06.003. 

Abstract. One of the 10 universal guidelines for healthy nutrition in a report of the World Cancer Research Fund released at the end of 2007 is to "limit intake of red meat and avoid processed meat", as a result of the "convincing evidence" for an association with an increased risk of colorectal cancer development. In the present paper, the scientific evidence for the association between processed meats intake and colorectal cancer development is explored and the most probable hypothesis on the mechanism underlying this relationship formulated. It seems that the present state of knowledge is not well understood but relates to a combination of haem iron, oxidative stress, formation of N-nitroso compounds and related residues in the digestive tract as the causal factors. Although criticisms of the inaccurate definition of processed meats and the insufficient accounting for the large variability in composition of meat products have been expressed, it is clear that the report urges proper action by the meat and nutrition research community and the meat industry. Research items that in our view should be addressed are discussed. They include: (1) evaluating the health risks associated with processed meats intake within the context of the supply of beneficial nutrients and other nutrition associated health risks; (2) definition of the role of nitrites and nitrates in meat processing; (3) investigating the role of red and processed meats on the endogenous formation of N-nitroso compounds in the digestive tract; and (4) developing improved processed meats using new ingredients.

(4) Oostindjer M, Alexander J, Amdam GV, Andersen G, Bryan NS, Chen D, Corpet DE, De Smet S, Dragsted LO, Haug A, Karlsson AH, Kleter G, de Kok TM, Kulseng B, Milkowski AL, Martin RJ, Pajari AM, Paulsen JE, Pickova J, Rudi K, Sødring M, Weed DL, Egelandsdal B. The role of red and processed meat in colorectal cancer development: a perspective. Meat Sci. 2014 Aug;97(4):583-96. doi: 10.1016/j.meatsci.2014.02.011.

Abstract. This paper is based on a workshop held in Oslo, Norway in November 2013, in which experts discussed how to reach consensus on the healthiness of red and processed meat. Recent nutritional recommendations include reducing intake of red and processed meat to reduce cancer risk, in particular colorectal cancer (CRC). Epidemiological and mechanistic data on associations between red and processed meat intake and CRC are inconsistent and underlying mechanisms are unclear. There is a need for further studies on differences between white and red meat, between processed and whole red meat and between different types of processed meats, as potential health risks may not be the same for all products. Better biomarkers of meat intake and of cancer occurrence and updated food composition databases are required for future studies. Modifying meat composition via animal feeding and breeding, improving meat processing by alternative methods such as adding phytochemicals and improving our diets in general are strategies that need to be followed up. Copyright © 2014. Published by Elsevier Ltd.

Haile D, Harding KL, McLaughlin SA, Ashbaugh C, Garcia V, Gilbertson NM, Kifle H, Parent MC, Sorensen RJD, Hay SI, Aravkin AY, Zheng P, Stanaway JD, Murray CJL, Brauer M. Health effects associated with consumption of processed meat, sugar-sweetened beverages and trans fatty acids: a Burden of Proof study. Nat Med. 2025 Jun 30. doi: 10.1038/s41591-025-03775-8. 

Abstract. Previous research suggests detrimental health effects associated with consuming processed foods, including processed meats, sugar-sweetened beverages (SSBs) and trans fatty acids (TFAs). However, systematic characterization of the dose-response relationships between these foods and health outcomes is limited. Here, using Burden of Proof meta-regression methods, we evaluated the associations between processed meat, SSBs and TFAs and three chronic diseases: type 2 diabetes, ischemic heart disease (IHD) and colorectal cancer. We conservatively estimated that-relative to zero consumption-consuming processed meat (at 0.6-57 g d-1) was associated with at least an 11% average increase in type 2 diabetes risk and a 7% (at 0.78-55 g d-1) increase in colorectal cancer risk. SSB intake (at 1.5-390 g d-1) was associated with at least an 8% average increase in type 2 diabetes risk and a 2% (at 0-365 g d-1) increase in IHD risk. TFA consumption (at 0.25-2.56% of daily energy intake) was associated with at least a 3% average increase in IHD risk. These associations each received two-star ratings reflecting weak relationships or inconsistent input evidence, highlighting both the need for further research and-given the high burden of these chronic diseases-the merit of continuing to recommend limiting consumption of these foods. © 2025. The Author(s), under exclusive licence to Springer Nature America, Inc.

(5) http://www.airc.it/cancro/disinformazione/additivi-conservanti-alimentari/

(6) EFSA Panel on Food Additives and Nutrient Sources added to Food (ANS), Mortensen A, Aguilar F, Crebelli R, Di Domenico A, Dusemund B, Frutos MJ, Galtier P, Gott D, Gundert-Remy U, Lambré C, Leblanc JC, Lindtner O, Moldeus P, Mosesso P, Oskarsson A, Parent-Massin D, Stankovic I, Waalkens-Berendsen I, Woutersen RA, Wright M, van den Brandt P, Fortes C, Merino L, Toldrà F, Arcella D, Christodoulidou A, Cortinas Abrahantes J, Barrucci F, Garcia A, Pizzo F, Battacchi D, Younes M. Re-evaluation of potassium nitrite (E 249) and sodium nitrite (E 250) as food additives. EFSA J. 2017 Jun 15;15(6):e04786. doi: 10.2903/j.efsa.2017.4786.

Abstract. The Panel on Food Additives and Nutrient Sources added to Food (ANS) provided a scientific opinion re-evaluating the safety of potassium nitrite (E 249) and sodium nitrite (E 250) when used as food additives. The ADIs established by the SCF (1997) and by JECFA (2002) for nitrite were 0-0.06 and 0-0.07 mg/kg bw per day, respectively. The available information did not indicate in vivo genotoxic potential for sodium and potassium nitrite. Overall, an ADI for nitrite per se could be derived from the available repeated dose toxicity studies in animals, also considering the negative carcinogenicity results. The Panel concluded that an increased methaemoglobin level, observed in human and animals, was a relevant effect for the derivation of the ADI. The Panel, using a BMD approach, derived an ADI of 0.07 mg nitrite ion/kg bw per day. The exposure to nitrite resulting from its use as food additive did not exceed this ADI for the general population, except for a slight exceedance in children at the highest percentile. The Panel assessed the endogenous formation of nitrosamines from nitrites based on the theoretical calculation of the NDMA produced upon ingestion of nitrites at the ADI and estimated a MoE > 10,000. The Panel estimated the MoE to exogenous nitrosamines in meat products to be < 10,000 in all age groups at high level exposure. Based on the results of a systematic review, it was not possible to clearly discern nitrosamines produced from the nitrite added at the authorised levels, from those found in the food matrix without addition of external nitrite. In epidemiological studies there was some evidence to link (i) dietary nitrite and gastric cancers and (ii) the combination of nitrite plus nitrate from processed meat and colorectal cancers. There was evidence to link preformed NDMA and colorectal cancers. © 2017 European Food Safety Authority. EFSA Journal published by John Wiley and Sons Ltd on behalf of European Food Safety Authority.