Frequently asked questions about avobenzone

What is avobenzone?
Also known as Parsol 17891, avobenzone is an ultraviolet A filter that was approved by the U.S. Food and Drug Administration for use in the U.S. in 1992.One of the most commonly used chemical sunscreen ingredients, avobenzone provides protection from a wide range of harmful UV rays by absorbing those rays and converting them to energy that is less damaging to the skin.3 Because avobenzone breaks down in the presence of sunlight, sunscreen formulations combine it with other ingredients, known as photostabilizers, that prevent it from breaking down.4

Why is avobenzone used in sunscreen?
Avobenzone is used in sunscreen due to its broad-range UV protection and ability to block UVA and UVB wavelengths, thereby limiting the impact of UV rays on skin.5 It is one of the few chemical sunscreen agents to offer protection from both UVA and UVB rays, both of which can cause skin cancer.1  

How does avobenzone protect your skin from UVA rays?
Avobenzone diminishes the penetration of UV light through the skin by absorbing UV radiation within a specific wavelength range (290-400 nm). The amount and wavelength of UV radiation absorbed are affected by the molecular structure of the sunscreen ingredient.5

Are there any health hazards associated with avobenzone?
The FDA has declared avobenzone safe to use in U.S. sunscreens in concentrations up to 3 percent, although formulas containing avobenzone may become toxic if used too often or in large doses.1,3 While there are few side effects believed to be associated with avobenzone itself, it may cause allergic reactions in some people; however, these reactions occur less frequently with avobenzone than with other sunscreen ingredients.6

In a 2005 study, researchers examined the penetration and retention of five commonly used sunscreen agents (avobenzone, octinoxate, octocrylene, oxybenzone and padimate O) in human skin after application in mineral oil to isolated human epidermal membranes. The results indicated that concentrations of each sunscreen found in human skin after topical application were at least five times lower than levels that could potentially cause toxicity.7

Concerns have been raised regarding avobenzone’s photostability and its potential to break down other sunscreen ingredients in products in which it is used. Octocrylene and mexoryl have been shown to stabilize avobenzone, allowing it to provide a long-lasting, stable and high level of UVA protection.2 The use of proper formulation strategies can ensure that sunscreens containing avobenzone provide protection, even over periods of prolonged exposure to UV rays.8

Is it true that avobenzone can break down into dangerous chemicals when exposed to ultraviolet light and/or chlorine?

Recent research studies examined the reactions of avobenzone under the influence of chlorine and/or UV irradiation. 9, 10 The toxicities of the majority of the substances created by these reactions remain unknown. These studies did not utilize photostabilized avobenzene, as would be found in commercially available sunscreen products, so their findings cannot be generalized to real-world scenarios of sunscreen use.

Is it safe to apply avobenzone to my skin?
Yes, it is safe to apply sunscreen containing avobenzone. Avobenzone is nontoxic and typically non-irritating to the skin. Its use in conjunction with photostabilizers, however, may increase the risk for skin irritation.1 While studies have demonstrated it may be absorbed by the body and secreted into urine, there is insufficient evidence to suggest avobenzone poses health risks in humans. Avobenzone absorption has not been studied in children or pregnant women, so parents and parents-to-be may wish to consider other sunscreen ingredients.1,11

References
1.    Avobenzone. (n.d.). Retrieved August 02, 2017, from https://www.truthinaging.com/ingredients/avobenzone
2.    FDA Sunscreen Final Monograph Ingredients. (n.d.). Retrieved August 02, 2017, from https://mycpss.com/skin/sunscreens/fda-sunscreen-final-monograph-ingredients/
3.    Avobenzone. (n.d.). Retrieved August 02, 2017, from http://www.thedermreview.com/avobenzone/
4.    Morabito, K., Shapley, N. C., Steeley, K. G., & Tripathi, A. (2011). Review of sunscreen and the emergence of non‐conventional absorbers and their applications in ultraviolet protection. International journal of cosmetic science, 33(5), 385-390.
5.    National Center for Biotechnology Information. PubChem Compound Database;
CID=51040, https://pubchem.ncbi.nlm.nih.gov/compound/Avobenzone#section=Top (Accessed Aug. 2, 2017).
6.    Antoniou, C., Kosmadaki, M. G., Stratigos, A. J., & Katsambas, A. D. (2008). Sunscreens–what's important to know. Journal of the European Academy of Dermatology and Venereology, 22(9), 1110-1119.
7.    Hayden, C. G. J., Cross, S. E., Anderson, C., Saunders, N. A., & Roberts, M. S. (2005). Sunscreen penetration of human skin and related keratinocyte toxicity after topical application. Skin pharmacology and physiology, 18(4), 170-174.
8.    Beasley, D. G., & Meyer, T. A. (2010). Characterization of the UVA protection provided by avobenzone, zinc oxide, and titanium dioxide in broad-spectrum sunscreen products. American journal of clinical dermatology, 11(6), 413-421.
9.    Trebše, P., Polyakova, O. V., Baranova, M., Kralj, M. B., Dolenc, D., Sarakha, M., & Lebedev, A. T. (2016). Transformation of avobenzone in conditions of aquatic chlorination and UV-irradiation. Water research, 101, 95-102.
10.    Wang, C., Kralj, M. B., Košmrlj, B., Yao, J., Košenina, S., Polyakova, O. V., & Trebše, P. (2017). Stability and removal of selected avobenzone's chlorination products. Chemosphere, 182, 238-244.
11.    Hayden, C. G., Roberts, M. S., & Benson, H. A. (1997). Systemic absorption of sunscreen after topical application. The Lancet, 350(9081), 863-864.