Hydroxyacetophenone
Also known as 4-hydroxyacetophenone, 4'-hydroxyacetophenone, p-hydroxyacetophenone, Piceol, SymSave H
“CIR Expert Panel says: safe as used in cosmetics.”
Hydroxyacetophenone (CAS 99-93-4; 4-hydroxyacetophenone, piceol) is a phenolic ketone used in cosmetics as an antioxidant and skin-conditioning agent, and marketed commercially as a preservative booster (SymSave H). The CIR Expert Panel reviewed available safety data and in October 2022 concluded it is safe in cosmetics at present practices of use and concentration (up to 5% in non-spray night products per 2020 survey data). It was not a dermal irritant or sensitizer when tested at 5% in guinea pig maximization and human repeated insult patch tests. One published case report describes allergic contact dermatitis from 0.6% aqueous hydroxyacetophenone in a facial cream (PMID 29341188), confirmed by positive patch test. Hydroxyacetophenone is not restricted under EU Cosmetics Regulation No. 1223/2009 (it is not Annex-listed). Genotoxicity studies showed it is non-genotoxic in bacterial reverse mutation assays; results in mammalian gene mutation assays were ambiguous at very high, cytotoxic concentrations only. Ocular irritation was observed in rabbit studies using undiluted material; the Panel noted manufacturers should ensure near-eye formulations are non-irritating.
CIR Expert Panel (2022) concluded safe in cosmetics at present practices of use and concentration — no numeric concentration cap imposed
Not a dermal irritant or sensitizer at 5% (maximum reported concentration of use) in both guinea pig maximization test and a 104-subject human repeated insult patch test
FEMA GRAS designation (FEMA No. 4330) as flavoring agent; JECFA also noted no safety concerns at dietary exposure levels
Functions as antioxidant and skin-conditioning agent per wINCi Dictionary; widely marketed as preservative booster (SymSave H) to enable paraben-reduction in formulations
Not restricted under EU Cosmetics Regulation No. 1223/2009 — not Annex V listed, confirming general-inventory (unrestricted) status in EU
- · Used in 7 baby products per 2022 VCRP data; concentration of use not reported for that product type
Severe ocular irritant in rabbits under undiluted test conditions (Draize score 63 unrinsed); the CIR Panel specifically noted that manufacturers should ensure near-eye products are non-irritating — used in eye lotions and makeup removers at up to 0.23%
One published case report of allergic contact dermatitis with positive patch test at 0.6% aqueous concentration in a 79-year-old male; 10 control subjects were negative, suggesting individual sensitization rather than population-level risk
Mammalian gene mutation assays (L5178Y mouse lymphoma cells) showed ambiguous genotoxicity signals in absence of metabolic activation at very high concentrations approaching cytotoxicity; three bacterial reverse mutation assays were uniformly negative
Safety Assessment of Hydroxyacetophenone as Used in Cosmetics — CIR Final Report, Release Date October 11, 2022 (Panel Meeting September …
“The Expert Panel for Cosmetic Ingredient Safety concluded that Hydroxyacetophenone is safe in cosmetics in the present practices of use and concentration described in this safety assessment.”— FR_Hydroxyacetophenone_092022.pdf, CONCLUSION section