What it is
The EU's CosIng database describes Alcohol Denat. as ethyl alcohol denatured with one or more denaturing agents in accordance with the national legislation of each EU country.1 Ethanol without a denaturant has its own label name, Alcohol.2 The US Food and Drug Administration (FDA) gives the reason for denaturing: the added denaturant makes the alcohol undrinkable, so that the ethyl alcohol in a cosmetic cannot be diverted illegally for use as an alcoholic beverage.3
EU cosmetics law names one denaturant directly. Methanol may be used only as a denaturant for ethanol and isopropyl alcohol, at up to 5% of that alcohol (Annex III, entry 52).4 The name Alcohol Denat. does not say which denaturant was used.
What it does in a formula
CosIng lists six functions for Alcohol Denat., the same six it lists for undenatured Alcohol: solvent, astringent, antimicrobial, viscosity controlling, antifoaming and fragrance.12 By CosIng's definitions, a solvent dissolves other components of a cosmetic, an astringent contracts or tightens the skin, and an antimicrobial prevents or slows microbial growth.5
A 2008 safety review of ethanol on the skin describes its wide use in products in direct contact with skin, from hand disinfectants to cosmetics such as hairsprays. It notes that ethanol applied to the skin acts as a penetration enhancer, and that its use is associated with skin irritation or contact dermatitis, especially in people with a deficiency of the enzyme aldehyde dehydrogenase.6
The drying alcohol group
Some people choose alcohol-free products because they believe ethyl alcohol dries out their skin or hair, the FDA notes.3 This site groups Alcohol, Alcohol Denat. and the SD Alcohol grades as Drying alcohol for people who avoid them; fatty alcohols and benzyl alcohol are never members. What studies show about ethanol and dryness is the subject of alcohol denat. in skincare.
SD Alcohol and other names
According to the FDA, US labels may show SD Alcohol (specially denatured alcohol) followed by a number or number-letter code showing how it was denatured, under the formulary of the US Bureau of Alcohol, Tobacco, Firearms and Explosives; SD Alcohol 23-A, 40 and 40-B are among those acceptable for cosmetics. Alcohol Denat. was introduced in Europe as a generic term to harmonise names internationally, so a label may carry both, as in "SD Alcohol-40 (Alcohol Denat.)".3
CosIng records the SD grades under Alcohol Denat., each with its denaturants. SD Alcohol 40-B, for example, is ethyl alcohol denatured with denatonium benzoate and t-butyl alcohol in accordance with US federal rules (27 CFR 21).7 Denatonium benzoate is a bitter substance; the Cosmetic Ingredient Review (CIR) reports it is effective as a denaturant at only 0.0006%.8
What official sources say
Ethanol has no entry of its own in the annexes of the EU cosmetics regulation4, and the EU glossary lists Alcohol Denat. as a label name.9 The CIR panel concluded in 2008 that, because applying these cosmetics to the skin or inhaling them does not produce significant systemic exposure to ethanol, their safety should be judged by the denaturant used. It found Alcohol Denat. safe as used when denatured with t-butyl alcohol, diethyl phthalate, methyl alcohol, salicylic acid, sodium salicylate or methyl salicylate, and considered the data sufficient for denatonium benzoate and SD Alcohol 40-B. For quassin, brucine and brucine sulfate, and SD Alcohol 39 and 40, which use them, it asked for more data.8
On the label
- Alcohol Denat., Denatured Alcohol or SD Alcohol plus a code: denatured ethanol. This site's checker reads Denatured Alcohol as Alcohol Denat.
- Alcohol on its own: ethyl alcohol.3
- Cetyl Alcohol, Cetearyl Alcohol and Stearyl Alcohol are fatty alcohols, with quite different effects on the skin.3
- Position: above 1%, EU lists run in descending order of weight10, so Alcohol Denat. near the top is one of the main ingredients.