Alcohol
Also known as Ethanol, Ethyl alcohol, Grain alcohol, Undenatured ethanol
“No regulator has issued a verdict on this ingredient.”
Ethanol (INCI: ALCOHOL, CAS 64-17-5) is a workhorse cosmetic solvent functioning as a fragrance/active carrier, astringent, antimicrobial at higher concentrations, and rapid-evaporation sensory agent. The regulatory landscape is structurally unusual: the Cosmetic Ingredient Review has not issued a standalone safety verdict on plain 'Alcohol' (verified absent from both the September 2022 and September 2020 QRTs — the alphabetical listing jumps from 'Alcaligenes Polysaccharides' directly to 'Alcohol Denat.' (Finding=UNS) at p. 17). The 2008 CIR report on Alcohol Denat. (IJT 27 Suppl 1:1-43) explicitly defers ethanol safety to denaturant safety, on the rationale that dermal and inhalation exposure to cosmetic ethanol does not produce significant systemic exposure to ethanol itself. The published cosmetic-science literature has examined ethanol directly: Lachenmeier (2008, PMID 19014531) reviewed topical ethanol broadly and found that regular dermal use produces blood ethanol/acetaldehyde levels well below acute-toxic thresholds in adults but flagged pediatric percutaneous toxicity through compromised skin and ALDH-deficiency-mediated heightened irritation; Cartner et al. (2017, PMID 27578266) ranked alcohol irritation severity n-propanol > isopropanol > ethanol and concluded ethanol has the mildest stratum corneum and keratinocyte effects of the three; Gajjar and Kasting (2014, PMID 25283951) quantified Franz-cell percutaneous ethanol absorption at <=0.3% and noted ethanol uniquely fits a simple diffusion model among the VOCs tested but causes measurable upper-skin swelling. The absence of an admissible CIR regulatory entry here is a structural pattern (mirrors AQUA): no jurisdiction in this directory's scope has issued a standalone ethanol verdict, so this packet documents that absence honestly rather than fabricating coverage.
Versatile solvent for fragrance, plant extracts, salicylates, and other lipophilic and amphiphilic actives — enables aqueous-phase delivery of compounds that water alone cannot solubilize
Rapid evaporation produces lightweight, non-residue sensory profile prized in toners, setting sprays, hair sprays, and fragrance products
Antimicrobial at concentrations ≥60-70%, providing self-preservation in alcohol-forward formulas (mouthwashes, sanitizers, splash colognes) and reducing reliance on added preservatives
Astringent / pore-tightening sensory effect at moderate concentrations is desirable in oily/acneic skin care toners — the same mechanism critics call 'drying' is a feature in that product category
Cartner et al. (2017) confirmed ethanol is the best-tolerated of the three common cosmetic alcohols (vs. isopropanol, n-propanol) for high-frequency-use applications such as hand sanitizers
Low percutaneous absorption (Gajjar/Kasting 2014: ≤0.3% Franz-cell absorption) means systemic exposure from cosmetic use is negligible in healthy adults
- · Pediatric percutaneous toxicity is documented through lacerated/compromised skin (Lachenmeier 2008) — a product-formulation/labeling concern, not an ingredient-level safety issue at intact-skin use
- · Flammability is a product-safety concern (Class I flammable liquid) but not an ingredient-toxicity issue; relevant to packaging and storage, outside the scope of dermal safety verdicts
Skin barrier disruption at high leave-on concentrations: ethanol extracts stratum corneum lipids and increases trans-epidermal water loss; Cartner et al. (2017) confirm ethanol perturbs keratinocyte metabolic activity and cytokine secretion (less so than n-propanol or isopropanol, but non-zero), and Gajjar/Kasting (2014) document upper-skin swelling on solvent exposure
Penetration-enhancer effect: Lachenmeier (2008) explicitly notes topical ethanol facilitates absorption of co-formulants; this is desirable in transdermal drug delivery but a safety concern when paired with sensitizers, allergens, or other irritants in leave-on cosmetics
ALDH (aldehyde dehydrogenase) deficiency, common in East Asian populations, produces heightened irritation and contact dermatitis from topical ethanol exposure due to slower metabolism of acetaldehyde at the skin surface (Lachenmeier 2008)
No CIR safety verdict on plain ethanol exists — the 2008 CIR Alcohol Denat. report explicitly defers ethanol safety to denaturant safety, leaving an INSUFFICIENT_DATA tier outcome that is structurally correct rather than a research gap
Pregnancy/lactation oral ethanol exposure is a well-established teratogen (FAS) but the evidence base does not extend to dermal cosmetic use at typical concentrations — no admissible regulatory body has restricted dermal cosmetic ethanol on this basis