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CAS Number: 7632-00-0
Synonyms: E250, nitrous acid sodium salt, nitrito de sodio (Spanish), natriumnitrit (German), sodium nitrite (common spelling), antinitrit (historical)
Physical Properties: White to slightly yellowish deliquescent crystalline powder or granules. Very highly soluble in water (approx. 82 g/100 mL at 20°C; 160 g/100 mL at 80°C). Slightly soluble in ethanol (0.3 g/100 mL). Insoluble in diethyl ether. Molecular weight 69.00 g/mol. Melting point 271°C (decomposes at about 320°C). Density 2.168 g/cm³. pH of 5% solution is 7.0–9.0 (slightly alkaline). Deliquescent (absorbs water from air, forming solution). Slowly oxidizes to sodium nitrate (NaNO₃) upon exposure to air. Decomposes in acidic media releasing brown NOx gases. Strong oxidizer; contact with reducing agents can cause fire, explosion, or toxic gas release.
Applications: Cured meat and poultry (bacon, ham, hot dogs, sausages including salami, summer sausage, pepperoni, bologna, corned beef, pastrami, Spam, Vienna sausages, canned luncheon meat, cured turkey, and chicken products). Fish curing (cured herring, salmon lox-style, and some smoked fish products). Some processed cheese spreads (very low use, often replaced by nitrate). Industrial uses include anticorrosion additive in industrial water treatment, hydraulic fracturing fluids in oilfields, metal finishing for phosphate coating, rubber accelerator, textile dyeing assistant, laboratory reagent for nitrosation reactions, Griess test for nitrite detection, and diazotization for azo dye synthesis. Medical uses include treatment of cyanide poisoning in combination with sodium thiosulfate (induces methemoglobinemia to bind cyanide) and as a vasodilator in angina pectoris (rare). Heat transfer salt (50:50 mixture with sodium nitrate for molten salt thermal storage in concentrated solar power plants).
Description:
Sodium nitrite (E250) is the most widely used nitrite salt in food preservation, particularly for cured meat products. It shares the same essential functions as potassium nitrite (E249): color development through the formation of pink-red cured color via nitrosomyoglobin, flavor enhancement by suppressing warmed-over flavor and contributing cured notes, and most critically, inhibition of Clostridium botulinum spore germination and toxin production. The mechanism of botulinum inhibition is concentration-dependent and pH-dependent: at pH above 6.0, higher nitrite levels are required, while at pH below 5.5 as in fermented sausages, lower levels are effective. In practical terms, 50 to 150 parts per million of ingoing nitrite provides a significant safety margin against botulism, even under mild temperature abuse.
Sodium nitrite is preferred over potassium nitrite for most applications because sodium nitrite is less expensive per unit of nitrite ion. For most cured meats, the sodium content contributed by sodium nitrite is negligible compared to sodium chloride (table salt). However, for extremely low-sodium products, potassium nitrite (E249) is selected. The food safety concerns regarding nitrites center on N-nitrosamine formation, as described under E249. Critically, nitrites in the presence of heme iron and reducing conditions typical of cured meat can also form nitric oxide (NO), which has beneficial cardiovascular effects when consumed in small amounts.
Epidemiological studies have shown a modest association between processed meat intake and colorectal cancer, leading the International Agency for Research on Cancer (IARC) to classify processed meat as Group 1 carcinogenic to humans, specifically attributing this effect partly to N-nitroso compounds (NOCs) formed from nitrites. However, the absolute risk increase is small, approximately an 18 percent increase per 50 grams of processed meat consumed daily, with a baseline lifetime risk of about 4.5 percent. For perspective, the risk from botulism, with a mortality rate of 5 to 10 percent even with treatment, far exceeds the carcinogenic risk from regulated nitrite use. Therefore, public health authorities including the World Health Organization, EFSA, and FDA continue to permit nitrite use within strict limits and with mandatory co-addition of ascorbate or erythorbate.
In the United States, sodium nitrite is regulated under 21 CFR 172.175 with a maximum ingoing amount of 200 parts per million calculated as NaNO₂, with ascorbate or erythorbate at 550 parts per million. The acceptable daily intake for sodium nitrite as nitrite ion is 0.07 milligrams per kilogram of body weight per day. Sodium nitrite is also an essential reagent in the chemical industry for diazotization reactions, converting aromatic amines into diazonium salts, which are then coupled to form azo dyes, representing over 50 percent of all synthetic dyes. In analytical chemistry, the Griess test detects nitrite by diazotizing sulfanilamide and coupling with N-(1-naphthyl)ethylenediamine to produce a pink azo dye, used in environmental monitoring and food safety testing.
Toxicologically, sodium nitrite has an oral LD₅₀ in rats of approximately 180 milligrams per kilogram. Acute poisoning from accidental ingestion of curing salt mixtures causes methemoglobinemia, and treatment is intravenous methylene blue, which reduces methemoglobin back to hemoglobin. Chronic exposure at high doses has been linked to increased tumors in animal studies, but at regulated food levels the risk is considered acceptable. One nuance is that sodium nitrite is also found in human saliva as a result of bacterial reduction of dietary nitrate from vegetables such as spinach, beets, and lettuce. Human salivary nitrite levels are typically 5 to 15 parts per million, which is similar to or higher than residual nitrite in cured meat after cooking, which is typically 5 to 20 parts per million. Therefore, the debate over nitrites in cured meats often overlooks natural dietary exposure from vegetables. Nevertheless, because vitamin C (ascorbic acid) naturally present in vegetables inhibits nitrosamine formation whereas cured meats may lack sufficient inherent antioxidants, the co-addition of ascorbate in meat processing is mandated.
SAFETY INFORMATION ABOUT E250 – SODIUM NITRITE
First aid measures:
Description of first aid measures:
General advice:
Consult a physician.
Show this safety data sheet to the doctor in attendance.
Move out of dangerous area:
If inhaled:
If breathed in, move person into fresh air.
If not breathing, give artificial respiration.
Consult a physician.
In case of skin contact:
Take off contaminated clothing and shoes immediately.
Wash off with soap and plenty of water.
Consult a physician.
In case of eye contact:
Rinse thoroughly with plenty of water for at least 15 minutes and consult a physician.
Continue rinsing eyes during transport to hospital.
If swallowed:
Do NOT induce vomiting.
Never give anything by mouth to an unconscious person.
Rinse mouth with water.
Consult a physician.
Firefighting measures:
Extinguishing media:
Suitable extinguishing media:
Use water spray, alcohol-resistant foam, dry chemical or carbon dioxide.
Special hazards arising from the substance or mixture
Carbon oxides, Nitrogen oxides (NOx), Hydrogen chloride gas
Advice for firefighters:
Wear self-contained breathing apparatus for firefighting if necessary.
Accidental release measures:
Personal precautions, protective equipment and emergency procedures
Use personal protective equipment.
Avoid breathing vapours, mist or gas.
Evacuate personnel to safe areas.
Environmental precautions:
Prevent further leakage or spillage if safe to do so.
Do not let product enter drains.
Discharge into the environment must be avoided.
Methods and materials for containment and cleaning up:
Soak up with inert absorbent material and dispose of as hazardous waste.
Keep in suitable, closed containers for disposal.
Handling and storage:
Precautions for safe handling:
Avoid inhalation of vapour or mist.
Conditions for safe storage, including any incompatibilities:
Keep container tightly closed in a dry and well-ventilated place.
Containers which are opened must be carefully resealed and kept upright to prevent leakage.
Storage class (TRGS 510): 8A: Combustible, corrosive hazardous materials
Exposure controls/personal protection:
Control parameters:
Components with workplace control parameters
Contains no substances with occupational exposure limit values.
Exposure controls:
Appropriate engineering controls:
Handle in accordance with good industrial hygiene and safety practice.
Wash hands before breaks and at the end of workday.
Personal protective equipment:
Eye/face protection:
Tightly fitting safety goggles.
Faceshield (8-inch minimum).
Use equipment for eye protection tested and approved under appropriate government standards such as NIOSH (US) or EN 166(EU).
Skin protection:
Handle with gloves.
Gloves must be inspected prior to use.
Use proper glove
removal technique (without touching glove's outer surface) to avoid skin contact with this product.
Dispose of contaminated gloves after use in accordance with applicable laws and good laboratory practices.
Wash and dry hands.
Full contact:
Material: Nitrile rubber
Minimum layer thickness: 0.11 mm
Break through time: 480 min
Material tested:Dermatril (KCL 740 / Aldrich Z677272, Size M)
Splash contact
Material: Nitrile rubber
Minimum layer thickness: 0.11 mm
Break through time: 480 min
Material tested:Dermatril (KCL 740 / Aldrich Z677272, Size M)
It should not be construed as offering an approval for any specific use scenario.
Body Protection:
Complete suit protecting against chemicals, The type of protective equipment must be selected according to the concentration and amount of the dangerous substance at the specific workplace.
Respiratory protection:
Where risk assessment shows air-purifying respirators are appropriate use a fullface respirator with multi-purpose combination (US) or type ABEK (EN 14387) respirator cartridges as a backup to engineering controls.
If the respirator is the sole means of protection, use a full-face supplied air respirator.
Use respirators and components tested and approved under appropriate government standards such as NIOSH (US) or CEN (EU).
Control of environmental exposure
Prevent further leakage or spillage if safe to do so.
Do not let product enter drains.
Discharge into the environment must be avoided.
Stability and reactivity:
Chemical stability:
Stable under recommended storage conditions.
Incompatible materials:
Strong oxidizing agents:
Hazardous decomposition products:
Hazardous decomposition products formed under fire conditions.
Carbon oxides, Nitrogen oxides (NOx), Hydrogen chloride gas.
Disposal considerations:
Waste treatment methods:
Product:
Offer surplus and non-recyclable solutions to a licensed disposal company.
Contact a licensed professional waste disposal service to dispose of this material.
Contaminated packaging:
Dispose of as unused product
