are not safe or effective for use as sunscreens.7) While benzophenones have the added ability to minimally absorb UVA in the 320-340nm spectrum, they also are a well-known contact allergen and photosensitizer.2,3,8,9 Of note, oxybenzone has been under scrutiny due to studies showing significant skin absorption and potential endocrine system disruption.3,10 Furthermore, oxybenzone and octinoxate (also as octyl methoxycinnamate) may be harmful to coral reefs; bills have been signed in both Hawaii and Key West banning the sale of sunscreens containing either of these starting in 2021.11,12
Avobenzone is the sole chemical approved by the FDA to afford UVA protection. Unfortunately, it is a highly unstable compound that shields only a small fraction of UVA. To mitigate this, stabilizers are frequently added in an attempt to retard its degradation by UV, and these combinations are often afforded proprietary names, such as “Helioplex†or “Cell-Ox Shield,†to name a few. Stabilizers may include ingredients like octocrylene or anti-oxidants/anti-inflammatories such as vitamin C, vitamin E, and botanical extracts.2,13,14
Which chemical sunscreen ingredients can be used in products manufactured outside the US, and how do they differ from Avobenzone?
A variety of sunscreen ingredients are used outside the US which are not FDA-approved and differ from US products in that they offer significantly increased UVA protection. The four primary ingredients targeting UVA in these sunscreen products include: Mexoryl SX (terephthalylidene dicamphor sulfonic acid), Mexoryl XL (drometrizole trisiloxane or ecamsule), Tinosorb S (also known as bemotrizinol or bisethylhexyloxyphenol methoxyphenyl triazine), and Tinosorb M (also known as bisoctrizole or methylene bis-benzotriazolyl tetramethylbutylphenol). These compounds offer better protection from UVA and free radicals than avobenzone and are frequently found in Asian, European, and South American sunscreens. Of note, the only two commercially available Mexoryl SX-containing products in the US are LaRoche- Posay Anthelios SX SPF 15 and Anthelios SPF 40, which were approved by the FDA in 2006 as complete products; the individual ingredient Mexoryl SX has not yet been approved.
According to the FDA in 2015, companies pursuing FDA approval for the four aforementioned sun-filtering chemicals have not yet provided enough evidence regarding their efficacy and safety,8 in spite of many years of safe use abroad. As such, it is unfortunate that these ingredients can’t be incorporated into US-manufactured sunscreen products because, according to a 2015 study, US sunscreens allow three times as much UVA penetration as do European sunscreens.15 In 2016, the Environmental Working Group estimated that 49% of US beach and body sunscreens could pass the FDA broad spectrum test but not the European UVA test.16 A 2017 study found that of a small sample of US sunscreen brands targeting UVA rays, nearly half did not pass the standards set by the European Union for assessing UVA protection.17
It has become much easier for the US consumer to access superior sunscreen products as the internet and international travel (currently limited by the COVID-19 pandemic) have flourished in recent years. As such, dermatologists well-versed in the subject should consider recommending those previously elusive Asian or European products to their patients as a way to better counter the harmful effects of UVA. Consumers must be careful to review ingredient lists when they are purchasing products online or in foreign pharmacies and to be aware that European and Asian products do not uniformly contain these ingredients, often using the same basic ingredient list as USmanufactured products. Some companies produce disparate products for each market, which means that the European version made by one company is generally entirely different from its US counterpart, in spite of very similar packaging.
How do physical sunblocks compare to chemical sunscreens?
Physical sunblock ingredients include titanium dioxide and zinc oxide. Both offer protection to some degree against UVA, UVB, and visible light by reflecting and refracting UV photons. However, it is important to counsel patients that zinc oxide has been shown to be far superior to titanium dioxide in UVA protection because of larger particle size, though possibly slightly less effective against UVB.2 The increased effectiveness of zinc oxide against UVA must be balanced against its chalky white appearance , which sometimes makes it less cosmetically appealing than titanium dioxide, which is frequently used as a makeup “primer†when combined with silicones. However, recent developments in manufacturing have led to more elegant formulations, using decreased particle size and even nanoparticles. The use of tinted products has become increasingly popular, particularly among patients with skin of color.
Why is an awareness of sunscreens and sunblocks important for dermatologists?
It should be expected that dermatologists understand the fundamentals of chemical sunscreens and physical sunblocks since we manage conditions strongly affected by UV radiation. For example, one of the mainstays of melasma treatment is effective sun protection by minimizing exposure to UVB as well as the pigment darkening effects of UVA. Furthermore, melasma patients also need to avoid UVC and visible light; as such, iron oxide in sunscreen or cosmetic products can be quite important in their treatment regimen.
What about antioxidants in sun protective agents?
Antioxidants can also be part of the toolbox to treat pigmentary disorders such as melasma, as they can help target the reactive
Avobenzone is the sole chemical approved by the FDA to afford UVA protection. Unfortunately, it is a highly unstable compound that shields only a small fraction of UVA. To mitigate this, stabilizers are frequently added in an attempt to retard its degradation by UV, and these combinations are often afforded proprietary names, such as “Helioplex†or “Cell-Ox Shield,†to name a few. Stabilizers may include ingredients like octocrylene or anti-oxidants/anti-inflammatories such as vitamin C, vitamin E, and botanical extracts.2,13,14
Which chemical sunscreen ingredients can be used in products manufactured outside the US, and how do they differ from Avobenzone?
A variety of sunscreen ingredients are used outside the US which are not FDA-approved and differ from US products in that they offer significantly increased UVA protection. The four primary ingredients targeting UVA in these sunscreen products include: Mexoryl SX (terephthalylidene dicamphor sulfonic acid), Mexoryl XL (drometrizole trisiloxane or ecamsule), Tinosorb S (also known as bemotrizinol or bisethylhexyloxyphenol methoxyphenyl triazine), and Tinosorb M (also known as bisoctrizole or methylene bis-benzotriazolyl tetramethylbutylphenol). These compounds offer better protection from UVA and free radicals than avobenzone and are frequently found in Asian, European, and South American sunscreens. Of note, the only two commercially available Mexoryl SX-containing products in the US are LaRoche- Posay Anthelios SX SPF 15 and Anthelios SPF 40, which were approved by the FDA in 2006 as complete products; the individual ingredient Mexoryl SX has not yet been approved.
According to the FDA in 2015, companies pursuing FDA approval for the four aforementioned sun-filtering chemicals have not yet provided enough evidence regarding their efficacy and safety,8 in spite of many years of safe use abroad. As such, it is unfortunate that these ingredients can’t be incorporated into US-manufactured sunscreen products because, according to a 2015 study, US sunscreens allow three times as much UVA penetration as do European sunscreens.15 In 2016, the Environmental Working Group estimated that 49% of US beach and body sunscreens could pass the FDA broad spectrum test but not the European UVA test.16 A 2017 study found that of a small sample of US sunscreen brands targeting UVA rays, nearly half did not pass the standards set by the European Union for assessing UVA protection.17
It has become much easier for the US consumer to access superior sunscreen products as the internet and international travel (currently limited by the COVID-19 pandemic) have flourished in recent years. As such, dermatologists well-versed in the subject should consider recommending those previously elusive Asian or European products to their patients as a way to better counter the harmful effects of UVA. Consumers must be careful to review ingredient lists when they are purchasing products online or in foreign pharmacies and to be aware that European and Asian products do not uniformly contain these ingredients, often using the same basic ingredient list as USmanufactured products. Some companies produce disparate products for each market, which means that the European version made by one company is generally entirely different from its US counterpart, in spite of very similar packaging.
How do physical sunblocks compare to chemical sunscreens?
Physical sunblock ingredients include titanium dioxide and zinc oxide. Both offer protection to some degree against UVA, UVB, and visible light by reflecting and refracting UV photons. However, it is important to counsel patients that zinc oxide has been shown to be far superior to titanium dioxide in UVA protection because of larger particle size, though possibly slightly less effective against UVB.2 The increased effectiveness of zinc oxide against UVA must be balanced against its chalky white appearance , which sometimes makes it less cosmetically appealing than titanium dioxide, which is frequently used as a makeup “primer†when combined with silicones. However, recent developments in manufacturing have led to more elegant formulations, using decreased particle size and even nanoparticles. The use of tinted products has become increasingly popular, particularly among patients with skin of color.
Why is an awareness of sunscreens and sunblocks important for dermatologists?
It should be expected that dermatologists understand the fundamentals of chemical sunscreens and physical sunblocks since we manage conditions strongly affected by UV radiation. For example, one of the mainstays of melasma treatment is effective sun protection by minimizing exposure to UVB as well as the pigment darkening effects of UVA. Furthermore, melasma patients also need to avoid UVC and visible light; as such, iron oxide in sunscreen or cosmetic products can be quite important in their treatment regimen.
What about antioxidants in sun protective agents?
Antioxidants can also be part of the toolbox to treat pigmentary disorders such as melasma, as they can help target the reactive
