Butylated Hydroxytoluene vs Red Dye 3: which is worse?

What is Butylated Hydroxytoluene?

Butylated hydroxytoluene (BHT) is a synthetic phenolic antioxidant preservative derived from petroleum. A white crystalline solid with formula C15H24O, it prevents fat oxidation in processed foods, cosmetics, and industrial applications. Often used synergistically with BHA.

What is Red Dye 3?

Red Dye 3 (erythrosine) is a synthetic cherry-pink fluorescent dye belonging to the xanthene class. It contains approximately 58% iodine by weight, distinguishing it from azo dyes. Its chemical formula is C20H6I4Na2O5. Approved since 1907, it is one of the oldest certified US food colorants and was notably the first synthetic food dye formally revoked by the FDA in decades.

Documented risks

Butylated Hydroxytoluene: BHT has complex, bidirectional carcinogenicity data — some NTP bioassays found liver tumors in female mice at high doses, while other studies suggested BHT might inhibit cancer initiation. IARC has not formally classified BHT due to conflicting evidence. A 2017 study linked BHT to thyroid hormone disruption in female rats. The American Academy of Pediatrics (2018) recommended reducing synthetic preservative exposure including BHT in children. Kellogg's uses vitamin E in European versions of cereals that contain BHT in US versions — a commercially meaningful substitution.

Red Dye 3: The FDA revoked Red Dye 3 authorization in January 2025, marking the first synthetic food dye ban by the FDA since Red Dye 2 in 1976. The revocation was triggered by the Delaney Clause, which mandates revocation of any food additive found to cause cancer in animals regardless of dose. The carcinogenicity data stems from studies showing that high doses of erythrosine caused thyroid follicular cell tumors in male rats. The mechanism is indirect: erythrosine suppresses thyroid-stimulating hormone (TSH) feedback by elevating thyroxine (T4) levels, causing chronic TSH suppression that promotes thyroid cell proliferation and ultimately tumor formation. This is a rat-specific mechanism related to their thyroxine-binding protein system, which differs from human biology. EFSA's 2011 comprehensive safety assessment concluded erythrosine was unlikely to be genotoxic at typical food use levels and set an ADI of 0.1 mg/kg body weight — one of the lowest for any food color. EFSA restricted EU use to cocktail cherries only (max 200 mg/kg). The high iodine content (58% by weight) raises concerns for thyroid-sensitive individuals. Excessive erythrosine intake could theoretically contribute to iodine overload and thyroid disruption, particularly in individuals with hyperthyroidism or Hashimoto's disease. The FDA had been aware of the rat thyroid tumor data since 1990 but delayed action for 35 years. Advocacy groups including CSPI petitioned for a ban since 1983. The January 2025 revocation finally addressed this long-standing regulatory gap.