Sodium nitrite

Sodium nitrite (E250) is the most widely used nitrite curing salt in the food industry, employed in bacon, ham, sausages, hot dogs, salami, and cured fish. In processed meat, it serves three interdependent functions: preservation against Clostridium botulinum and other anaerobic pathogens; colour fixation through reaction with myoglobin to form stable pink nitrosomyoglobin; and flavour development through Maillard-type reactions with meat proteins. Sodium nitrite is typically applied as a pre-mixed curing salt containing 0.6% NaNO₂ in sodium chloride (Prague powder #1) to ensure safe and accurate dosing.

JECFA established a group ADI of 0.07 mg/kg body weight per day for sodium and potassium nitrites (evaluated 2002). This very low ADI reflects serious dose-dependent toxicological concerns. At elevated doses, nitrite oxidises haemoglobin to methaemoglobin, impairing oxygen transport — a risk most acute in infants and individuals with G6PD deficiency. More significantly from a population health perspective, nitrite can react with secondary amines and amides in food and in the gastrointestinal tract to form N-nitrosamines, a class of compounds with established carcinogenic activity in multiple animal species. The European Food Safety Authority's 2017 comprehensive assessment (EFSA Journal 15:4786) determined that nitrite from cured meats contributes meaningfully to overall N-nitrosamine exposure and represents a long-term cancer risk concern, particularly for colorectal cancer.

Sodium nitrite is regulated under EU Annex II at maximum permitted levels of 100–150 mg/kg and under US FDA 21 CFR §172.175. IARC's 2015 Monograph classifying processed meat as a Group 1 carcinogen explicitly cited nitrite-derived N-nitrosamines as part of the mechanistic evidence. Regulatory bodies have not banned nitrites because their anti-botulism benefit is considered to outweigh the cancer risk at current permitted levels — but they have progressively reduced maximum levels. Consumers wishing to minimise exposure should choose fresh unprocessed meats and limit consumption of commercially cured products.