At a glance
| Chemical family | UV filter — dibenzoylmethane derivative (butyl methoxydibenzoylmethane / Parsol 1789) |
| CAS number | 70356-09-1 |
| Classification | Not IARC classified. Photounstable — degrades under UV to triplet benzophenone and other products. FDA GRASE determination pending. Not an endocrine disruptor in available evidence |
| Where you encounter it | Sunscreens (the dominant UVA filter globally); SPF moisturisers; cosmetics with UV protection; transfers to bedding from skin application |
| Sleep micro-environment relevance | Transfers from skin to pillowcases and sheets during sleep. Photodegradation products formed during daytime UV exposure may be present on skin at bedtime |
Regulatory & certification status
| European Union | Permitted up to 5% in cosmetics (Annex VI). No safety concerns raised at this concentration by SCCS. Regulatory |
| United States | FDA permitted up to 3% in OTC sunscreens. GRASE determination pending under 2019 proposed rule — FDA requested additional safety data including systemic absorption studies. Regulatory |
| Canada | Health Canada permitted up to 3% in sunscreens. Regulatory |
| International | Not IARC classified. Not banned in any jurisdiction. The dominant UVA filter in global sunscreen markets. Photostability is a formulation concern, not a regulatory ban trigger. Regulatory |
What it is
Avobenzone is a dibenzoylmethane derivative that absorbs UVA radiation (320-400 nm). It was approved in the US in 1988 and has become the dominant UVA filter in sunscreens globally, particularly in markets where newer UVA filters (Tinosorb S, Tinosorb M) are not yet approved. IARC has not evaluated avobenzone. Unlike octinoxate and oxybenzone, avobenzone has not shown significant endocrine-disrupting activity in most studies. Its primary concern is photostability: avobenzone degrades under UV exposure, losing its UVA-filtering capacity. The photodegradation pathway generates triplet-state benzophenone, which has been shown to damage DNA through a photosensitisation mechanism. Formulators stabilise avobenzone by combining it with octocrylene or other photostabilisers, but degradation still occurs during extended sun exposure.
Where it shows up in bedding
Avobenzone enters the bedroom by transferring from sunscreen-treated skin to pillowcases and sheets during sleep. By bedtime, avobenzone on the skin may have partially degraded from daytime UV exposure — meaning both the parent compound and its photodegradation products (including benzophenone derivatives) are present on the skin and transfer to bedding. Unlike the parent avobenzone, these photoproducts have not been well characterised toxicologically. The clinical significance of sleeping on photodegraded avobenzone residues is unknown. Regular face-washing before bed and weekly pillowcase laundering reduce accumulation.
Citations
- Mturi, G.J. and Martincigh, B.S. (2008). Photostability of the sunscreening agent 4-tert-butyl-4'-methoxydibenzoylmethane (avobenzone) in solvents of different polarity. Journal of Photochemistry and Photobiology A: Chemistry, 200(2-3): 410-420. Source Peer-reviewed
- FDA (2019). Proposed Rule: Sunscreen Drug Products for Over-the-Counter Human Use. Source Regulatory
- Schwack, W. and Rudolph, T. (1995). Photochemistry of dibenzoylmethane UVA filters, Part 1. Journal of Photochemistry and Photobiology B: Biology, 28(3): 229-234. Source Peer-reviewed
Frequently asked questions
Is avobenzone dangerous?
Avobenzone has not shown significant endocrine-disrupting activity, unlike some other UV filters. The primary concern is photostability — it degrades under UV and its degradation products include reactive benzophenone species. At recommended sunscreen concentrations and with proper formulation (photostabilisers), avobenzone is considered safe by regulatory agencies. FDA has requested additional systemic absorption data.
Why does avobenzone degrade in sunlight?
Avobenzone absorbs UVA energy, which excites the molecule from its stable enol form to an unstable keto form. The keto form can undergo irreversible fragmentation reactions, producing benzophenone and other products that no longer absorb UVA. Formulators combat this by adding photostabilisers like octocrylene, which quench the excited keto state before it fragments.
Related compounds
Embr is a sleep environment company researching and addressing the chemistry of the bedroom. Research and product development in progress.
Last reviewed 2026-07-08. If you find a factual error, contact us.