Yellow Dye 6 vs Butylated Hydroxyanisole: which is worse?

What is Yellow Dye 6?

Yellow Dye 6 (Sunset Yellow FCF) is a synthetic orange-yellow azo dye derived from petroleum. It produces a bright orange-yellow color and is structurally similar to Yellow 5 but produces a more orange shade. Its chemical formula is C16H10N2Na2O7S2.

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

Yellow Dye 6: Yellow Dye 6 was included in the 2007 Lancet study (McCann et al.), which found that a mixture of six dyes including Yellow 6 and sodium benzoate significantly increased hyperactivity in children. EFSA confirmed the effect warranted mandatory warning labels in the EU. EFSA's 2009 re-evaluation examined animal carcinogenicity data and found some studies showing adrenal tumors in male mice at high doses. EFSA set an ADI of 2.5 mg/kg body weight — lower than Yellow 5's ADI of 7.5 mg/kg, reflecting greater concern. The review noted limitations in the available data. Impurity concerns: commercial batches of Yellow 6 have been found to contain aromatic amine impurities including benzidine and 4-aminobiphenyl — both IARC Group 1 human carcinogens. A 1992 CSPI analysis documented these impurities, citing them as reason for concern. A 2007 study in Toxicological Sciences found Yellow 6 altered zinc and iron biomarker levels in rat blood at high doses, raising mineral metabolism concerns. Human relevance at typical exposure is unclear. Hypersensitivity reactions including urticaria, rhinitis, and contact dermatitis are documented. Cross-reactivity with aspirin is reported similarly to Yellow 5. In April 2025, the FDA announced plans to phase out Yellow 6 with other petroleum-based dyes.

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.