Sulphur Dioxide
The short version
Free sulphur dioxide — the active species in all sulfite preservation and a major label allergen.
A preservative and antioxidant (sulphur dioxide). It works well, but sulfites can trigger breathing problems in people with asthma and reactions in other sensitive people, so labels must declare them. That sensitivity risk is why we flag it.
Safety profile
JECFA's group ADI for sulfur dioxide and sulfites is 0–0.7 mg/kg body weight, expressed as SO2 (1998). In 2022 EFSA withdrew its temporary group ADI of 0.7 mg SO2/kg body weight per day, finding the toxicity data inadequate to derive an ADI, and concluded that estimated dietary exposure raises a safety concern. A documented allergen — triggers severe asthma in an estimated 5–10% of asthmatics and rare anaphylaxis. Mandatory allergen labelling above 10 mg/kg in the EU, US, and most jurisdictions. Destroys dietary thiamine (vitamin B1).
Sources
- EFSA FAF Panel — Follow-up of the re-evaluation of sulfur dioxide (E 220) and sulfites (E 221–228), EFSA Journal 20(11):e07594 (2022), doi:10.2903/j.efsa.2022.7594 — European Food Safety Authority (EFSA), 2022. ADI status; safety concern at current exposure
- JECFA evaluation summary — Sulfur dioxide (INS 220), group ADI 0–0.7 mg/kg bw (1998) — WHO/IPCS INCHEM (JECFA), 1998. JECFA group ADI 0–0.7 mg/kg bw as SO2
- 21 CFR 182.3862 — Sulfur dioxide (GRAS, with use restrictions) — US eCFR (Office of the Federal Register / FDA), 2026. US status and restrictions; thiamine (vitamin B1) concern
- Regulation (EU) No 1169/2011 on food information to consumers — Annex II (substances causing allergies or intolerances) — EUR-Lex (European Union), 2011. EU mandatory declaration above 10 mg/kg as SO2
Checked against these sources on .
Educational information only. Not medical, dietary or veterinary advice. Spotted an error? Tell us.