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E252PreservativeModerate concern
Potassium Nitrate
In plain words
The short version
Saltpeter — a slow-release curing agent that converts to nitrite during meat ageing.
Why we flag it amber
A traditional curing salt that converts to nitrite in the meat, protecting against botulism but able to form nitrosamines — compounds linked to cancer. That trade-off is why we flag it.
Safety profile
ADI of 0–3.7 mg/kg body weight. Lower direct toxicity than nitrite but converts to nitrite in storage and digestion, where the same N-nitrosamine concerns apply. The combined nitrite + nitrate dietary load (including from vegetables) drives the risk profile.
The detail
Naturally occurring as the mineral niter; also produced industrially by reaction of potassium chloride with nitric acid. One of the oldest meat-curing agents — used for millennia in traditional preserved meats.
Used in dry-cured hams, salami, and some traditional cheeses where slow nitrate-to-nitrite conversion by microbial reductases gives a gradual, sustained curing action. In the EU, since 9 October 2025 the maximum amount that may be added to most non-heat-treated meat products is 90 mg/kg, rising to 180 mg/kg for some traditional cured products, expressed as nitrate ion. For hard, semi-hard and semi-soft cheese the limit from 9 October 2026 is 75 mg/kg in the cheese milk, also expressed as nitrate ion. Also a flame retardant and traditional pickling agent.
Colorless to white crystals, highly soluble in water. Stable in dry storage. Strong oxidizer.
Permitted in the EU and globally for charcuterie and certain cheeses with maximum limits. In the EU, Regulation (EU) 2023/2108 lowered the maximum amounts that may be added, applying from 9 October 2025 for meat products and from 9 October 2026 for hard, semi-hard and semi-soft cheese.
Sources
- WHO JECFA database: Potassium nitrate (INS 252), ADI 0–3.7 mg/kg bw as nitrate ion — World Health Organization / JECFA, 1995. ADI of 0–3.7 mg/kg bw
- EFSA: Re-evaluation of sodium nitrate (E 251) and potassium nitrate (E 252) as food additives, EFSA Journal 2017;15(6):4787 — European Food Safety Authority, 2017. ADI 3.7 mg/kg bw/day maintained; total dietary nitrate drives exceedance
- EUR-Lex: Commission Regulation (EU) 2023/2108 amending Annex II to Regulation (EC) No 1333/2008 as regards nitrites (E 249–250) and nitrates (E 251–252) — European Union (EUR-Lex), 2023. Lowered EU maximum added amounts for nitrates in meat (from 9 Oct 2025) and cheese (from 9 Oct 2026)
- eCFR: 21 CFR 181.33 Sodium nitrate and potassium nitrate (prior sanctions), current text — U.S. Government (eCFR, Office of the Federal Register), 2026. US status as a curing agent for meat and poultry
Checked against these sources on .
Educational information only. Not medical, dietary or veterinary advice. Spotted an error? Tell us.