E252 – POTASSIUM NITRATE

CAS Number: 7757-79-1
 Synonyms: E252, nitric acid potassium salt, saltpeter, niter, saltpetre (historical), nitrate of potash, kaliumnitrat (German), nitrato de potasio (Spanish), niter (mineral form)
Physical Properties: White to colorless prismatic crystals or crystalline powder (odorless, cooling saline taste). Moderately soluble in water (approx. 31.6 g/100 mL at 20°C; 247 g/100 mL at 100°C). Very slightly soluble in ethanol. Slightly soluble in glycerol. Molecular weight 101.10 g/mol. Melting point 334°C (decomposes at ~400°C to potassium nitrite and oxygen). Density 2.109 g/cm³. pH of 5% solution is 6.5–7.5 (neutral). Very low hygroscopicity (does not absorb significant moisture from air; much less deliquescent than sodium nitrate or nitrites). Strong oxidizer when molten or heated; supports rapid combustion; forms explosive mixtures with organic matter, charcoal, sulfur, and metals.
Applications: Cured meat and cheese (dry-cured hams including Serrano, Iberian, Parma, Prosciutto; dry sausages such as Spanish chorizo and Italian salami; dry-cured bacon; corned beef; deli meats). Cheese (Emmental, Gruyère, Gouda, Edam, and other Swiss-type cheeses to prevent late blowing, especially where sodium nitrate is undesirable due to sodium content or taste interference). Pharmaceuticals (ingredient in desensitizing toothpaste for sensitive teeth at 5 percent concentration, blocking dentinal tubules and reducing nerve conduction; also in antihypertensive formulations, rare). Industrial uses (component of black powder or gunpowder: 75 percent KNO₃, 15 percent charcoal, 10 percent sulfur; present-day pyrotechnics including fireworks, rocket motors, smoke bombs, model rocket engines; blasting agents such as ANFO substitute; potassium-rich fertilizer; heat transfer salt for concentrated solar power plants with NaNO₃). Food preservation historically (saltpeter mixed with salt for preserving meat before refrigeration). Laboratory reagent (strong oxidizing agent for organic synthesis, nitration reactions, and preparation of potassium nitrite). Food storage (some brine recipes for pickles and corned meats).
Description:
 Potassium nitrate (E252) is a naturally occurring mineral salt (niter or saltpeter) that, like sodium nitrate (E251), serves as a slow-release nitrite source for cured meats, fish, and certain cheeses. Its use as a food additive is almost identical to that of sodium nitrate, with two key differences. First, potassium nitrate provides potassium ion (K⁺) instead of sodium, making it suitable for low-sodium and reduced-sodium cured meats where sodium chloride (regular salt) is also lowered. Second, potassium nitrate is less soluble than sodium nitrate, with solubility of 31.6 grams per 100 milliliters versus 88 grams per 100 milliliters at 20°C, which can affect brine concentration rates in some curing processes.
Historically, saltpeter was the primary agent for preserving meat long before refrigeration, often in the form of "saltpetered" or "corned" beef, where "corned" refers to the coarse salt and saltpeter crystals. In modern practice, potassium nitrate is still used for premium dry-cured hams and sausages where traditional recipes are followed. For example, Parma ham (Prosciutto di Parma) traditionally uses sea salt with small amounts of potassium nitrate at up to 250 parts per million. The nitrate is converted to nitrite by the natural bacterial flora during the 12 to 24 month aging process, yielding a deep red color and characteristic flavor while ensuring that residual nitrite levels at consumption are extremely low, below 10 parts per million. Potassium nitrate adds no undesirable taste at these levels.
In cheese production, potassium nitrate is preferred over sodium nitrate (E251) for certain European Protected Designation of Origin (PDO) cheeses because it does not contribute sodium, and the potassium ion may influence starter culture metabolism and cheese texture. The safety profile of potassium nitrate is similar to that of sodium nitrate: low acute toxicity with an oral LD₅₀ in rats of approximately 3750 milligrams per kilogram, but concerns about reduction to nitrite and subsequent nitrosamine formation apply. The acceptable daily intake for potassium nitrate as nitrate ion is 0 to 3.7 milligrams per kilogram of body weight per day, the same as for sodium nitrate.
For consumers, the most relevant exposure difference is the sodium contribution. Using potassium nitrate instead of sodium nitrate reduces added sodium by about 25 percent per gram of additive because KNO₃ contains approximately 38 percent potassium and no sodium, whereas NaNO₃ contains approximately 27 percent sodium. In a typical dry-cured ham containing 100 milligrams per kilogram of nitrate, the sodium saved is negligible at 27 milligrams of sodium per kilogram of meat. But in products with higher nitrate levels, such as 500 milligrams per kilogram in some Traditional Speciality Guaranteed products, the sodium saved can become meaningful.
Outside of food, potassium nitrate is famous as the oxidizing component of black powder (gunpowder), first formulated in 9th century China. When heated, KNO₃ decomposes according to the reaction 2 KNO₃ + heat → 2 KNO₂ + O₂, and the released oxygen rapidly oxidizes the charcoal (carbon) and sulfur, producing hot gases including CO₂, SO₂, and N₂ that expand and propel projectiles. While black powder is obsolete for military use, having been replaced by smokeless powders, it remains the standard for fireworks, hobby rockets, and reenactment cannons. In the European Union, E252 is permitted for use in dry-cured meat products, with regulatory limits varying by country. The EFSA re-evaluation in 2017 confirmed that nitrate intake from food additives does not exceed safe levels for most populations, except for some children with high processed meat consumption.
Unlike nitrites (E249 and E250), nitrates themselves are not directly toxic; their hazard stems only from conversion to nitrite. For this reason, some regulators such as Canada permit nitrate without a strict ADI provided labeling is clear. Nevertheless, consumer pressure has reduced nitrate use in many products, often replaced by celery juice concentrate, which is naturally high in nitrate. As with nitrites, the "clean label" celery alternative produces identical nitrate residues, making the substitution largely semantic. Potassium nitrate also has medical uses: in toothpaste at 5 percent concentration, it reduces dentin hypersensitivity by depolarizing nerve endings in the dental pulp and blocking pain transmission. The FDA has approved potassium nitrate toothpaste as effective for sensitive teeth, with brand examples including Sensodyne and Colgate Sensitive Pro-Relief. The amount of potassium nitrate ingested from swallowed toothpaste residue is negligible compared to food exposure.

SAFETY INFORMATION ABOUT E252 – POTASSIUM NITRATE

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