Sodium sulfite

Sodium sulfite is a sulphite compound used as a preservative to inhibit microbial growth and prevent oxidative browning in food. It is applied to dried fruits, wine, fruit juices, tinned vegetables, and pre-packaged cut vegetables, among other products. Its preservative action is closely related to that of sulphur dioxide (E220), and both are governed by the same toxicological framework.

JECFA evaluated sodium sulfite in 1967 as part of the sulphite group and established a group ADI of 0.7 mg per kilogram of body weight per day, expressed as sulphur dioxide equivalents. For a 70 kg adult this equates to approximately 49 mg per day as SO₂. This ADI applies collectively to all sulphite compounds in the diet, so combined intake from multiple sulphite-containing products can accumulate. Sensitive individuals — particularly those with asthma — may react at much lower concentrations.

Sulphites including E221 are approved globally but are subject to mandatory allergen labelling in the EU, US, Canada, Australia, and many other jurisdictions whenever present above 10 mg/kg or 10 mg/L as SO₂. Products must declare contains sulphites on the label. People with asthma or sulphite sensitivity should read labels carefully, as even small amounts can trigger bronchospasm or allergic-type reactions.