BHT: How Safe Is This Cosmetic Preservative?
Arin Editorial · how this is made
You have probably seen the abbreviation BHT on the ingredient list of a lipstick, moisturizer or toothpaste. Its full name is butylated hydroxytoluene. This synthetic antioxidant is used in both food and cosmetics to keep oils from going rancid.
What is BHT?
BHT is a synthetic molecule made by a chemical reaction between p-cresol and isobutylene. It slows down the reaction of oils with oxygen. It is found mainly in oil-containing creams, lipsticks and toothpastes to extend shelf life. Because the name is long, it is listed simply as BHT on formulas.
What does it do?
Its main job is antioxidant: it delays the oil in the formula from turning smelly or changing color. That puts it under the 'preservative' umbrella in cosmetics, but it does not kill microorganisms; it mainly protects the oil.
Regulatory status
The European Union cosmetics regulation lists BHT as a restricted substance. The UK scientific advisory group SAG-CS proposed maximum limits of 0.1% in toothpaste, 0.001% in mouthwash and 0.8% in other cosmetic products. This proposal is not legally binding yet; the EU's SCCS has also been asked whether these concentrations are safe. Being on the restricted list means manufacturers cannot use the ingredient without limits.
Why is it debated?
There are concerns that BHT could cause cancer or affect the hormone system. IARC put the current evidence in the 'not classifiable as to carcinogenicity' group; that does not mean 'safe', it means 'not enough data'. So it is not called a carcinogen, but it is not called safe either. Genetic damage tests are mixed: some show an effect, some do not. Skin and eye irritation tests are also inconsistent. IARC's classification is a hazard assessment; it does not mean the hazard will happen at cosmetic use levels.
It is a restricted substance in cosmetics in the European Union; the UK scientific body proposed limits of 0.1% in toothpaste, 0.001% in mouthwash and 0.8% in other products.
If you want to avoid BHT, check the ingredient list for 'BHT' or 'butylated hydroxytoluene'. Products sold in the EU must follow the restricted list; the position on the label gives you a rough idea: closer to the top means more in the formula. The proposed limits for oral care are much lower than for skin products, so if you want to avoid it in toothpaste or mouthwash, you can choose a BHT-free alternative.
Sources
- European Commission, Regulation (EC) No 1223/2009, Annex III
- IARC Monographs, Volume 40, Supplement 7