Propyl Gallate vs Azodicarbonamide: which is worse?

What is Propyl Gallate?

Propyl gallate is a synthetic antioxidant preservative derived from gallic acid and propanol. It prevents oxidation of fats and oils, extending shelf life of fat-containing foods. It is often used in combination with BHA and BHT for synergistic antioxidant effect. Chemical formula: C10H12O5.

What is Azodicarbonamide?

Azodicarbonamide (ADA) is a synthetic chemical used in the food industry as a flour bleaching agent and dough conditioner, and industrially as a blowing agent in foam rubber and plastic production. Its chemical formula is C2H4N4O2. When it reacts with water or heat, it breaks down into biurea (primary product) and semicarbazide (SEM).

Documented risks

Propyl Gallate: Animal studies have shown propyl gallate may cause liver damage at high doses. Concerns about estrogenic activity have been raised — some studies suggest propyl gallate may weakly mimic estrogen. Contact dermatitis and allergic reactions are documented in both food and cosmetic applications. Japan banned propyl gallate for food use as part of its precautionary approach to synthetic food preservatives. NTP bioassays found dose-dependent liver effects. EFSA's re-evaluation set an ADI of 0.1 mg/kg body weight — one of the lowest ADIs for food additives, reflecting toxicological concern.

Azodicarbonamide: ADA's primary food safety concern is its breakdown to semicarbazide (SEM) during baking. In a 2002 study, SEM was found to increase the incidence of vascular tumors in female mice at high doses. This single animal finding was sufficient under the EU's precautionary principle to ban ADA in food use in 2005. The FDA conducted a comprehensive SEM exposure assessment in 2016, concluding that US population exposure to SEM from ADA-treated bread is many orders of magnitude below doses showing tumor effects in rodents and does not warrant regulatory change. This reflects the FDA's risk-based approach. Urethane (ethyl carbamate) is another potentially harmful breakdown product of ADA. Urethane is classified as an IARC Group 2A probable human carcinogen. Small amounts of urethane can form from SEM in fermented or alcohol-containing environments. The 2014 'yoga mat chemical' controversy highlighted ADA's dual use: it is the same chemical used as a blowing agent in foam rubber and plastic manufacturing — including yoga mats. Consumer advocacy blogger Vani Hari's 'Food Babe' campaign led over 50,000 people to petition Subway, which voluntarily removed ADA from its bread in 2014. The dual industrial-food use raised public concern even though ADA's behavior in each context is chemically different. From occupational health: workers exposed to ADA powder in bakery or plastic manufacturing settings can develop occupational asthma. WHO recognizes ADA as a respiratory sensitizer in occupational settings, though dietary exposure through bread is fundamentally different from inhalation exposure.