Bht
Also known as Butylated hydroxytoluene, 2,6-Di-tert-butyl-4-methylphenol, DBPC, BHT-food grade
“CIR Expert Panel says: safe as used in cosmetics.”
BHT (butylated hydroxytoluene; CAS 128-37-0; C15H24O) is a synthetic phenolic antioxidant used in cosmetics at concentrations typically from 0.0002% to 0.5%. The CIR Expert Panel first assessed BHT in 2002 (IJT 21(Suppl.2):19-94) and reaffirmed the safe-as-used conclusion in a 2023 re-review (IJT 42(Suppl.3):17S-19S, PMID 37751543), finding the ingredient safe in the practices of use and concentration described. The EU SCCS issued Opinion SCCS/1636/21 (adopted Dec 2021) concluding BHT is safe up to 0.8% in leave-on/rinse-off products, 0.1% in toothpaste, and 0.001% in mouthwash, with concentration limits set in the context of potential endocrine disrupting properties; the SCCS noted the weight of evidence did not support classifying BHT as endocrine active. A 2022 New Approach Methodology (NAM) study (PMID 36161505) found BHT did not connect to endocrine-active reference compounds for estrogen, androgen, thyroid, or steroidogenesis pathways.
Effective lipid-soluble antioxidant (phenolic radical scavenger) that protects oils, waxes, and other oxidation-sensitive actives from rancidity, extending product shelf life
CIR Expert Panel reaffirmed safe as used in cosmetics in 2023 re-review, covering the current range of product types and concentrations
EU SCCS concluded safe up to 0.8% in leave-on and rinse-off cosmetics after full evaluation including endocrine disruption data review
Long history of use in both cosmetics and food (FDA GRAS as food antioxidant), providing extensive real-world safety data
- · Animal feeding studies at high doses show liver and kidney toxicity and tumor promotion; these effects occur at systemic exposures orders of magnitude above cosmetic dermal absorption levels
- · Environmental persistence and potential for bioaccumulation are noted in consumer environmental health literature; SCCS mandates do not address environmental safety
Consumer and advocacy groups (EWG, Campaign for Safe Cosmetics) raise endocrine disruption concerns based on in vitro and animal studies; however, the SCCS (2021) and CIR (2023) both reviewed this evidence and concluded the weight of evidence does not support endocrine disruption classification at cosmetic use concentrations
SCCS noted some positive results in individual endocrine-disruption studies, leading it to set conservative concentration limits, particularly for oral-contact products (mouthwash: 0.001%, toothpaste: 0.1%)
BHT can produce positive reactions in provocative patch tests at 1-2% concentrations in a small subset of individuals; contact sensitivity is documented but low-prevalence at cosmetic use levels (typically 0.01-0.5%)
CIR Quick Reference Table (Oct 2024) — BHT row: Finding=S (Safe), Citation=IJT 42(Suppl. 3):17S-19S, 2023; IJT 21(Suppl.2):19-94, 2002
“BHT | S | | IJT 42(Suppl. 3):17S-19S, 2023; IJT 21(Suppl.2):19-94, 2002”— QRT-Update-100824_0.pdf, B section (BHT row, immediately after BHA row)
Burnett C et al. BHT – Butylated Hydroxytoluene (CIR re-review, reaffirmed safe as used), Int J Toxicol 42(Suppl. 3):17S-19S, 2023
Final Report on the Safety Assessment of BHT, Int J Toxicol 21(Suppl. 2):19-94, 2002
SCCS Opinion on Butylated Hydroxytoluene (BHT), SCCS/1636/21, adopted 2 December 2021
“BHT is safe as an ingredient up to a maximum concentration of 0.001% in mouthwash and 0.1% in toothpaste. BHT is safe as an ingredient up to a maximum concentration of 0.8% in other leave-on and rinse-off products. [SCCS/1636/21, adopted 2 December 2021, considering concerns related to potential endocrine disrupting properties of BHT]”— SCCS/1636/21 opinion summary, health.ec.europa.eu/publications/butylated-hydroxytoluene-bht_en