Introduction:

Korean sunscreens have long been praised as the best possible form of sun protection. However, when it comes to preventing pigmentation and protecting against long wave UVA and blue light, which type of sunscreen performs better? An all-mineral sunscreen or one of the many popular Korean sunscreens? Since Korean sunscreens can take many different forms, sometimes including newer generation of UV filters and sometimes using the same filters found in the US, we took a look at six of the current most popular Korean types of sunscreens and their UV filters. Since Korean sunscreens do not disclose concentrations of their UV filters, we modelled different variations to see how this might impact their long wave UVA and blue light protection. We compared this with a 25% zinc oxide sunscreen and used sunscreen optimizers from BASF and DSM to compare results.

Background: What part of sunlight creates pigmentation?

It’s well known that sunlight creates pigmentation in skin. However, we now have a better understanding that specific portions of light are more responsible than initially thought for creating excess pigmentation, namely long wave UVA light into visible light (specifically blue light within the 400 nm to 500 nm range). While UV light comprises 5% of what reaches Earth, the full spectrum of visible light comprises 50%. It’s now clear that low grade, chronic exposure to blue light excites skin’s chromophores, creating a pathway to oxidative damage and pigmentation. “While protecting against UVR is still of the utmost importance, it should not stop at the virtual wavelength of 400 nm…indeed, certain skin chromophores appear to be specifically activated by blue light.” (Schutz, Rolf. 2021). Many studies have also confirmed that protection against blue light induced pigmentation is even more critical for people of colour (type IV-type VI skin). (Mahmoud Bh, et al. 2010).

The question becomes which specific UV filters are better at protecting against the longest wavelengths of UVA (370 nm to 400 nm) and against blue light (400 nm).

The best UV filters for blue light protection: Particulate Grade Filters Zinc Oxide and Methylene Bis-Benzotriazolyl Tetramethylbutylphenol (MBBT)

While zinc oxide works as a UV absorber mainly by way of absorption, similar to other ‘chemical UV filters, it still has one marked distinction in the roughly 5% of light scattering and reflection that it does perform. Its critical point of difference is that it does this 5% of light scattering and reflection in the crucial range of long wave UVA into visible light. MBBT (brands name Tinosorb M, Parsol MAX) is also considered a particulate grade UV filter (it is insoluble and large in size) and also does some amount of reflection and light scattering in this range.

Of all the available UV filters around the world, zinc oxide and MBBT remain the two best options for long wave UVA protection (370 nm and beyond) and blue light protection. Of course, the top six most popular Korean sunscreens do not use any zinc oxide at all. Only some use MBBT, and it is currently unknown what concentration of MBBT is used.

The six most popular Korean sunscreens and their UV filters

We should preface the fact that a sunscreens quality or lack of quality is not related to its country of manufacture. It does not really make sense to paint all Korean sunscreens as being the same. The Korean government allows for the use of newer UV filters compared to the FDA. However, this does not mean that all Korean sunscreen brands make use of these new filters or use them effectively at the right concentration. One Korean sunscreen that had been voted as the ‘best overall’ had the same combination of UV filters as any non-mineral American one. Our continued objection to Korean sunscreens remains that it’s impossible to know the concentration of UV filters. It remains challenging to even know which UV filters are used, as their INCI names are included with all other ingredients in one combined list (compared to North American sunscreens that have distinct Active and Inactive Ingredient sections). Many websites that sell these products to North Americans do not even list the ingredients at all. The overall message to the consumer is that it does not matter what UV filters are used or what their concentration is.

As part of our process, we looked at six of the most popular Korean sunscreens as sold to North America. We did a quick google search and also looked at press with the usual “Best Korean sunscreens according to…” to guide use. Two of the formulas had identical UV filters. One formula used the same standard concentration of UV filters as North America, i.e. avobenzone, octocrylene and homosalate. We also looked at two different formulas from one brand, one of which was just recently launched and removed MBBT completely from the formula.

As mentioned, we had no way to no for sure what concentration of each UV filter was used. For some formulas we had to rely on third party websites like INCI Decoder to even get a full ingredient list that we could then parse out which UV filters were used. We assumed that in all of these instances the INCI lists were accurate and used the standard practice of listing ingredients in descending order (first ingredient has the highest concentration, last ingredients have the lowest concentration). In this way, we were able to make very educated guesses about the concentrations used of each UV filter. However, only the sunscreen brand can confirm for sure.

From there, we then chose the UV filter most likely to give long wave UVA and blue light protection. Of all the sunscreens we looked at, these long wave UVA filters included Bis-Ethylhexyloxyphenol Methoxyphenyl Triazine(BEMT, Tinosorb® S, Parsol Shield), Methylene Bis-Benzotriazolyl Tetramethylbutylphenol (nano), active amount (MBBT, Tinosorb® M, Parsol MAX) and Butyl Methoxydibenzoylmethane (Avobenzone, Parsol 1789). We then trialled these at different concentrations to see how this impacted the blue light protection. Data was taken from the BASF Solar Simulator.

Discussion of Results: it matters what’s in your sunscreen and the concentration used

We think a lot of consumers make these basic assumptions when it comes to the efficacy of Korean sunscreens in general. They use ‘next-gen’ UV filters and since each formula uses a wide array of them, they have to have full UV coverage. Most people do not feel they need or want to know what’s in their sunscreen, it’s enough to know it’s Korean. However, our research shows that while there are many UV filters that are available to a Korean sunscreen formulator, there remain only a very select few that actually can protect against long wave UVA light. Furthermore, this confirms that of the most popular UV filters, zinc oxide and MBBT are really the only choice for effective blue light protection.

As the table above shows, Avobenzone remains a poor choice for any kind of visible light protection. It also notably stops performing UV attenuation at 380 nm (long wave UVA). BEMT (Tinosorb S and Parsol Shield) does not provide effective blue light protection (and does not provide the same quality protection as MBBT, although they are often marketed interchangeably).

Finally, when it comes to MBBT, concentration matters. It matters significantly. At concentrations of 1% of lower, MBBT does not provide even close to the same quality of blue light protection. Unfortunately, it is currently impossible for any consumer to know what concentration of MBBT is in their current Korean sunscreen.

Furthermore, a 25% zinc oxide sunscreen offers comparable protection in the long wave UVA as a sunscreen that contains 3-5% MBBT (Tinosorb M, Parsol Max). At lower MBBT concentrations, a 25% zinc oxide outperforms MBBT in long wave UVA protection. Zinc oxide outperforms all concentrations of MBBT past 400 nm (Blue Light).

Key Take-Aways:

• The quality of a sunscreen has nothing to do with where it was manufactured. Instead, the UV filters used and their concentration matters.

• Korean sunscreens do have access to a greater variety of UV filters but that does not mean every formula uses them and/or in the correct concentration. A formula may use many different UV filters but typically only one provides long wave UVA and blue light protection if at all.

• Concentration matters and it remains impossible for a consumer to be able to know what is in a Korean sunscreen unless a brand discloses.

• Zinc oxide and MBBT remain the two best UV filters for long wave UVA and blue light protection when used at the correct concentration, even when taking into account the many globally approved UV filters.

• Avobenzone and BEMT provide little to no blue light protection.

• For best long wave UVA, MBBT should be used in concentrations higher than 3%. Lower than 3% , long wave UVA is compromised and blue light protection is greatly reduced.

• A 25% zinc oxide sunscreen gives the best blue light protection of any possible sunscreen and thus is an excellent choice for preventing pigmentation and chronic oxidative stress to skin.

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References:

1. Schulz R. Blue light and skin. In: Surber C, Osterwalder U, editors. Challenges in Sun Protection. Current Problems in Dermatology. Basel: Karger; 2021. Vol. 55, p. 354-373.

2. Mahmoud, bh,Ruvulo E, et al. Impact of longwavelength UVA and visible light on melanocompetent skin. J Invest Dermatology. 2010; 130 (8):2092-7. dot 10.1038/jjd.2010.95