Tertiary-butylhydroquinone

Tertiary-butylhydroquinone, or TBHQ, is a synthetic preservative added to fats and oils to prevent them from going rancid. It is a type of phenol used to extend the shelf life of many processed foods, including fast-food frying oils, crackers, chips, and frozen meats. The FDA permits its use up to a limit of 0.02% of a food's fat content. While effective at preserving food quality, a growing body of scientific research has raised concerns about its potential effects on the immune system, particularly regarding allergic reactions and response to infections.

Aliases / Common Names: t-Butylhydroquinone, TBHQ, E319, Mono-tert-butylhydroquinone, 2-(1,1-dimethylethyl)-1,4-benzenediol Regulatory Status & Exposure: The FDA approved TBHQ in 1972 and regulates its use under 21 CFR 172.185, limiting it to 0.02% (200 ppm) of the fat content in food. The Joint FAO/WHO Expert Committee on Food Additives (JECFA) established an Acceptable Daily Intake (ADI) of 0.7 mg/kg of body weight in 1997, which was later confirmed by the European Food Safety Authority (EFSA) in 2004. While average U.S. intake is likely below this ADI, estimates suggest that individuals on high-fat diets, a characteristic of many fast-food consumers, may exceed it. TBHQ is not banned for safety in the EU or Canada.   Technical Evidence: The toxicological profile of TBHQ is complex. The most comprehensive long-term study by the National Toxicology Program (NTP) found no evidence of carcinogenic activity in rats or mice. However, a significant body of recent research points to immunotoxicity as a primary concern. Animal studies have shown that dietary TBHQ at human-relevant exposure levels can exacerbate allergic sensitization and anaphylaxis, an effect linked to its activation of the Nrf2 pathway, which promotes a Th2-type immune response. Other studies suggest TBHQ may impair T-cell activation, potentially weakening the immune response to infections like influenza and reducing vaccine efficacy. Some in-vitro studies have also shown it can cause chromosomal damage in mammalian cells after metabolic activation.   Fast-Food Context: TBHQ is highly prevalent in the fast-food industry due to its effectiveness in stabilizing frying oils, which are subjected to high heat and repeated use. Adding TBHQ to oil blends for items like french fries and chicken nuggets extends the oil's life, reducing costs and maintaining product consistency. This practice makes fast-food meals a significant and frequent source of TBHQ exposure for many consumers, increasing the likelihood of high-intake individuals exceeding the established ADI.   Sensitive Populations / Notes: Individuals with pre-existing allergies or compromised immune systems may be more susceptible to the potential immunomodulatory effects of TBHQ. Due to their lower body weight and potentially high consumption of processed foods relative to their size, children may have higher exposure levels, and EFSA has noted they are the group most likely to exceed the ADI in high-intake scenarios.

We assign the high tier using published research, regulatory guidance, and PRūF’s additive taxonomy. Restaurant usage is derived from public ingredient disclosures and mapped to menu items where this additive appears.