Sulfur Dioxide vs Yellow Dye 5: which is worse?

What is Sulfur Dioxide?

Sulfur dioxide (SO2) is a colorless gas used as a food preservative and antioxidant. It is the primary active form of the sulfite family of food additives. It is generated by burning sulfur or as a byproduct of certain chemical processes. In food use, it is released from various sulfite salts (E221-E228) and directly applied to some foods.

What is Yellow Dye 5?

Yellow Dye 5 (tartrazine) is a synthetic lemon-yellow azo dye derived from petroleum. It produces a bright, stable yellow color in acidic conditions and is one of the most widely used yellow dyes globally. Its chemical formula is C16H9N4Na3O9S2.

Documented risks

Sulfur Dioxide: Same as sodium sulfite: sulfite-sensitive individuals (1% of population, 5% of asthmatics) can experience severe reactions. SO2 in wine has been identified as a contributor to wine-induced headache and asthmatic episodes. Occupational exposure to SO2 gas causes respiratory irritation, bronchospasm, and lung damage at higher concentrations — relevant to workers in winemaking and food processing but not typical dietary exposure levels.

Yellow Dye 5: Yellow Dye 5 was one of six dyes studied in the landmark 2007 McCann et al. study in The Lancet. The study found statistically significant increases in hyperactivity in children ages 3 and 8–9 given a mixture containing tartrazine and sodium benzoate. EFSA reviewed the evidence and confirmed the effect was real, mandating the EU warning label from 2010. A 2012 review in Neurotherapeutics (Arnold et al.) confirmed that artificial food colors including tartrazine have a small but statistically significant adverse effect on children's behavior that is not confined to those with diagnosed ADHD. Tartrazine is one of the most documented causes of food dye hypersensitivity. Cross-reactivity with aspirin (acetylsalicylic acid, ASA) is well established in allergy literature: individuals with aspirin hypersensitivity have elevated risk of reacting to tartrazine. Symptoms include urticaria, angioedema, rhinitis, and in rare cases anaphylaxis. Prevalence of tartrazine sensitivity is estimated at 0.1% of the population but higher in aspirin-sensitive individuals. Because of this known hypersensitivity risk, the FDA specifically requires Yellow No. 5 to be declared by name on US food labels — an exceptional requirement not applied to most other additives, reflecting the FDA's acknowledgment of this real clinical concern. EFSA's 2009 re-evaluation found no evidence of genotoxicity in standard test systems at food use levels, setting an ADI of 7.5 mg/kg body weight, but noted in vitro evidence at higher doses. In April 2025, the FDA announced plans to phase out Yellow 5 along with other petroleum-based dyes.