Author: Vanessa Ngan, Staff Writer, 2012.
Avobenzone is a dibenzoylmethane derivative and is a chemical substance that is used in sunscreen products. It is able to absorb the full spectrum of UVA rays and has been around since the 1980’s in sunscreen formulations worldwide. It does not provide protection against UVB rays.
More recently, studies have shown that avobenzone is photo-unstable and degrades quickly when exposed to sunlight. It can lose up to 50-90% of efficacy in the first hour of sun exposure. For this reason, avobenzone is now often formulated with photostabilising chemicals such as octocrylene and bemotrizinole. Other studies have shown absorption of avobenzone by the skin and have cautioned its use as with PABA-containing sunscreen agents.
Another dibenzoylmethane derivative, isopropyl dibenzoylmethane (Eusolex 8020), was found to cause a high number of photosensitivity reactions and for these reasons was discontinued in 1993.
Contact allergy to pure avobenzone is rare. Most allergic reactions arise from the other chemicals avobenzone has been formulated with to make it more photostable.
Avobenzone allergy is diagnosed by performing specific patch tests and photopatch tests.
If you are diagnosed with avobenzone allergy then avoid exposure to avobenzone containing products. Management of avobenzone dermatitis may be treated as for any acute dermatitis/eczema; this may include treatment with topical corticosteroids and emollients.
Read product labels and avoid products that contain avobenzone or dibenzoylmethane derivatives. Your dermatologist may have further specific advice, particularly if you are highly sensitive.
CAS number: 70356-09-1
Appearance: colourless crystals
Sensitizer: dibenzoylmethane derivatives
Patch test: avobenzone 10% in petrolatum
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