Red Dye 40 vs Butylated Hydroxyanisole: which is worse?

What is Red Dye 40?

Red Dye 40 (Allura Red AC) is a synthetic petroleum-derived azo dye that produces a bright red-orange color. It belongs to the monoazo chemical class and is highly water-soluble, with the formula C18H14N2Na2O8S2. It replaced amaranth (Red Dye 2), which was banned in the US in 1976 following cancer concerns.

What is Butylated Hydroxyanisole?

Butylated hydroxyanisole (BHA) is a synthetic phenolic antioxidant preservative derived from petroleum. It is a mixture of two isomeric compounds (2-BHA and 3-BHA). BHA prevents fats and oils from oxidizing (going rancid), extending shelf life. Its chemical formula is C11H16O2.

Documented risks

Red Dye 40: Red Dye 40 has been linked to several health concerns, particularly in children. The most documented association is with hyperactivity and ADHD-related behavior. A landmark 2007 study in The Lancet (McCann et al.) found that a mixture of six artificial dyes including Red 40, combined with sodium benzoate, significantly increased hyperactivity scores in children ages 3 and 8–9. This prompted EFSA to require the 'may have adverse effect on activity and attention in children' warning label across the EU and UK. A 2012 meta-analysis in Neurotherapeutics (Arnold et al.) confirmed a small but statistically significant deleterious effect of artificial food colors on children's behavior, even in those without diagnosed ADHD. The authors described the effect as a public health issue rather than merely an ADHD issue. Regarding carcinogenicity: commercial batches of Red 40 contain trace amounts of benzidine, an IARC Group 1 human carcinogen. A 1994 study in Food and Chemical Toxicology documented benzidine contamination. The FDA maintains that exposure is below harmful thresholds, but the Center for Science in the Public Interest (CSPI) has cited this contamination in multiple ban petitions. Allergic reactions are documented: Red 40 can trigger histamine release leading to hives, rhinitis, and in rare cases anaphylaxis. Cross-reactivity with aspirin is established in aspirin-sensitive individuals. Gut health: A 2021 study in Nature Communications (Kwon et al.) found Red 40 may worsen inflammatory bowel disease and induce colitis-like symptoms in genetically susceptible mice by triggering immune responses in gut-associated lymphoid tissue. In April 2025, HHS Secretary RFK Jr. announced the FDA would phase out Red 40 and 7 other petroleum-based dyes from the US food supply.

Butylated Hydroxyanisole: BHA is classified by the International Agency for Research on Cancer (IARC) as Group 2B (possible human carcinogen) based on studies showing it causes papillomas and squamous cell carcinomas of the forestomach in rats, hamsters, and mice at high doses. A 1983 NTP bioassay confirmed these findings. The National Toxicology Program lists BHA as 'reasonably anticipated to be a human carcinogen' in its Report on Carcinogens. The forestomach is an anatomical structure found in rodents but not humans, creating some uncertainty about direct extrapolation. EFSA's 2012 re-evaluation (EFSA Journal 2012;10(10):2588) concluded that BHA may have endocrine-disrupting potential based on animal data showing interactions with estrogen receptors and androgenic hormone pathways. EFSA found the ADI of 1 mg/kg body weight but noted concerns about endocrine effects. Japan banned BHA for use in foods containing fats and oils, consistent with its generally precautionary approach to synthetic food preservatives. In cosmetics, the EU Scientific Committee on Consumer Safety (SCCS) has assessed BHA and found potential endocrine-disrupting effects at dermal exposure levels. EWG rates BHA as high-concern in Skin Deep cosmetics database. The antioxidant paradox applies: while BHA prevents lipid oxidation in foods, it may paradoxically act as a pro-oxidant in certain biological contexts at certain doses.