Sulfur Dioxide vs Titanium Dioxide: 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 Titanium Dioxide?

Titanium dioxide (TiO2) is a naturally occurring white mineral used as a food colorant, whitening agent, and opacity enhancer. In food applications, it exists as nano-sized and micro-sized particles. It is one of the most widely produced industrial minerals globally, used in paints, plastics, sunscreens, and food products.

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.

Titanium Dioxide: The EU banned titanium dioxide as a food additive in 2022 following EFSA's landmark 2021 safety assessment (EFSA Journal 2021;19(5):6585), which concluded that titanium dioxide 'can no longer be considered safe as a food additive.' The primary concern is genotoxicity from nanoparticles: EFSA determined it was impossible to rule out the risk of DNA damage (genotoxicity) from TiO2 nanoparticles at typical food use exposure levels. In vitro studies have demonstrated that TiO2 nanoparticles cause DNA strand breaks in intestinal epithelial cells and induce oxidative stress. A 2019 study in Nature Communications found TiO2 nanoparticles could disrupt gut microbiome balance and intestinal barrier function in mice models. Multiple studies have suggested effects on gut permeability and immune function. IARC classifies titanium dioxide as Group 2B (possible human carcinogen) for inhalation exposure in occupational settings — primarily relevant to workers handling TiO2 dust, based on rat lung cancer studies. While inhalation and oral exposure are different routes, EFSA determined that the genotoxicity concerns from nanoparticles applied to oral food use as well. Following the EU ban, California attempted to pass legislation banning TiO2 in candy (along with other additives) in 2022. The bill was signed in modified form. Mars reformulated EU Skittles to remove TiO2. The US FDA has not announced specific action on food-grade TiO2 as of 2025, though USRTK and other organizations are calling for a US ban.