Finding the right sunscreen for dark skin tones

The sun care market is transforming. With consumers paying more attention to their skin health, there is a clear need for more differentiated personal care products, including sunscreens. By Dr Myriam Sohn, BASF principal scientist – scientific liaisons – IP manager sun care

Consumer preferences are manifold – factors like skin sensitivity, application formats, sensorial expectations, purpose, and geographical location of use need to be considered. Skin colour can also be a decisive factor when looking for the right sun care product. For example, dark skin is more prone to develop hyperpigmentation such as dark spots induced by long UVA exposure. From this type of consumer perspective, it makes sense to not only look for a high SPF but to prioritise UVA1-VIS protection in a sunscreen. Formulators are challenged to develop more customised sun care products tailored to the specific needs of consumers who do not want to settle for the promise of a one-size-fits-all solution.  

Different skin types  

The categorisation of individuals into different sun-reactive skin types dates to the 1970s. At the time, Fitzpatrick proposed a working classification system for clinical practice to determine the appropriate UVA dose for UV therapy to treat psoriasis.¹ His system is still used today. It encompasses six skin phototypes based on skin colour and on how they react to erythema and tanning after initial sun exposure. The system showed that natural skin pigmentation and sun reactivity are inversely related. The scale goes from skin phototype I, which corresponds to fair-skinned individuals (FSI) who are highly sensitive to sun exposure, burn easily after a brief period of UV exposure and do not tan, to phototype VI, which corresponds with dark-skinned individuals (DSI) who rarely burn and tan easily.  

The reason for darker skin tones is melanin, a natural pigment produced in melanocyte cells in the skin’s basal layer. The content, composition, transfer, and distribution of melanin-containing melanosomes to keratinocytes differ according to skin colour, thereby explaining the global diversity in skin tones.^2-4 Melanin pigments provide natural or so-called ‘constitutive’ photoprotection in the UV-range, as they absorb at a maximum around 335nm.^{5, 6} Melanin exists in two forms:  

1. Reddish-yellow pheomelanin, which is predominant in fair skin types and has a weaker capacity for photoprotection 
2. Brownish-black eumelanin, which is prevalent in dark skin types and provides greater photoprotection.⁷  

Previous studies reported an erythemal constitutive protection rate of more than 10 times in DSI compared to FSI.^{8, 9} Furthermore, DNA damage is observed to be lower and DNA-repairing mechanisms better in DSI. However, the natural photoprotection of dark skin also has its limits.  

Limitations in natural photoprotection  

It has been reported that people with skin types IV to VI may experience severe sunburn after prolonged sun exposure and are susceptible to DNA damage.^{10, 11}  

People with high levels of melanin are particularly affected by hyperpigmentation disorders and melasma, which are mainly attributed to the exposure to UVAI and the blue light (BL) band of the visible (VIS) light spectrum.  

Another important factor is that dark-skinned populations tend to use sunscreen less frequently compared to fair-skinned populations as reported by several studies. This is often due to lower awareness and perceived risk of developing skin cancer.^{12, 13} 

Photodamage, however, occurs and accumulates in all skin phototypes including DSI, leading to visible effects after a certain point.   

Focus on balanced protection  

Considering that 90% of UVA reaches the Earth’s surface, it makes sense that UVA1-VIS protection should not be neglected in a sun care product. UVA rays not only cause premature skin ageing but also contribute to skin cancer.  

In 2006, the European Commission recommended that sunscreen products should have UVA protection of at least one third of their SPF value.¹⁴ This led to a major improvement in the performance of sunscreens in the UVA range and ensures that a minimum UVA protection level is provided with a more balanced UV spectrum.  

However, a significant amount of UVA – particularly UVAI rays – is still not being blocked by sunscreen products with a UVA protection value that is one third of their SPF. Since daily exposure to low UV doses has been shown to contribute to long-term effects, daycare products should prioritise well-balanced UVA protection to an even greater extent.^{15, 16} 

Tailored sun care to encourage use   

An important lever to encourage the use of sunscreen among DSI is the development of tailored sun protection products for their specific performance needs and sensorial expectation. Therefore, a one-size-fits-all-skin-types sunscreen cannot be the solution.  

Besides the need for a high UVA1-VIS protection to protect DSI from hyperpigmentation appearing later in age, another important aspect is that sunscreens should be invisible on dark skin after application to increase user compliance.  

The first requirement can be achieved by using organic nanoparticulate filters such as Methylene Bis-Benzotriazolyl Tetramethylbutylphenol (MBBT) and Tris-Biphenyl Triazine (TBPT). Due to their particulate nature, they can scatter UV light and reduce the transmission of UVA1 and BL in the visible light spectrum.¹⁷ However, these types of UV filters have the drawback of inducing a greyish, ashy finish on dark skin after application, which is aesthetically undesirable. This problem can be solved by adding iron oxide pigments to the formulation to mask the ashiness caused by nanoparticulate filters, improving aesthetical acceptance and subsequent compliance. Nanoparticulate filters may also contribute to direct visible light absorption.¹⁸ Therefore, a sunscreen developed for DSI should focus on high UVA-VIS protection, meaning a UVA-PF to SPF ratio higher than the classical European Commission recommendation of 1/3 to 1/2 or even 2/3. In the current situation, consumers should pay attention to choosing sunscreens or day care products that have at least the UVA logo to guarantee minimum UVA protection related to the SPF value, while waiting for more customised and better UVA protection products.  

Since the natural level of photoprotection against sunburn in DSI is significantly higher than in FSI, a sunscreen with SPF 30 seems reasonable to avoid excessive amounts of unnecessary UV filters.   

Table 1 shows a sunscreen formulation specifically designed for the needs of DSI. It contains iron oxide to counteract the greyish look that could arise from the particulate filter Tris-Biphenyl Triazine (TBPT), which is used for its high contribution to UVA1-VIS protection. 

Making the best choice   

It has been shown that using sunscreen is an important additional means of photoprotection, not only for FSI but also for DSI. A universal solution is, however, not the best option and consumers should carefully choose the most suitable sun care product for their specific needs.  

Formulators should pay special attention to UVA-VIS protection when working on formulations for DSI. Organic particulate UV filters are particularly suitable in terms of performance in the BL range. Combining them with iron oxide pigments can help to make the sun care product aesthetically more pleasing by masking the ashy effect they induce on dark skin. Formulations with SPF 30 and optimised UVA1 – BL protection seem reasonable for DSI.  

References:  

1. Fitzpatrick TB. The validity and practicality of sun reactive skin type I through type VI. Arch Dermatol. 1988;124(6):869-71.  

2. Alaluf S, Atkins D, Barrett K, Blount M, Carter N, Heath A. Ethnic variation in melanin content and composition in photoexposed and photoprotected human skin. Pigment Cell Res. 2002;15(2):112-8.  

3. Montagna W, Prota G, Kenney JA. Black Skin: Structure and Function: Academic Press; 1993.  

4. Brenner M, Hearing VJ. The protective role of melanin against UV damage in human skin. Photochem Photobiol. 2008;84(3):539-49.  

5. Ou-Yang H, Stamatas G, Kollias N. Spectral responses of melanin to ultraviolet A irradiation. J Invest Dermatol. 2004;122(2):492-6.   

6. Kollias N, Sayre RM, Zeise L, Chedekel MR. New trends in photobiology: photoprotection by melanin. J. Photochem. Photobiol. B. 1991;9(2):135-60.  

7. Kollias N, Malallah YH, AlAjmi H, Baqer A, Johnson BE, Gonzalez S. Erythema and melanogenesis action spectra in heavily pigmented individuals as compared to fair-skinned Caucasians. Photodermatol. Photoimmunol. Photomed. 1996;12(5):183-8.  

8. Cripps DJ. Natural and artificial photoprotection. J Invest Dermatol. 1981;77(1):154-7.  

9. Kaidbey KH, Agin PP, Sayre RM, Kligman AM. Photoprotection by melanin – comparison of black and caucasian skin. JAAD. 1979;1(3):249-60.  

10. Hall HI, Rogers JD. Sun protection behaviors among African Americans. Ethn Dis. 1999;9(1):126-31.  

11. Tadokoro T, Kobayashi N, Zmudzka BZ, Ito S, Wakamatsu K, Yamaguchi Y, et al. UV-induced DNA damage and melanin content in human skin differing in racial/ethnic origin. Faseb j. 2003;17(9):1177-9.  

12. Buster KJ, You Z, Fouad M, Elmets C. Skin cancer risk perceptions: a comparison across ethnicity, age, education, gender, and income. J Am Acad Dermatol. 2012;66(5):771-9.  

13. Buchanan Lunsford N, Berktold J, Holman DM, Stein K, Prempeh A, Yerkes A. Skin cancer knowledge, awareness, beliefs, and preventive behaviors among black and hispanic men and women. Prev Med Rep. 2018; 12:203-9.  

14. Commission Recommendation of 22 September 2006 on the efficacy of sunscreen products and the claims made relating thereto.   

15. Wright CY, Reeder AI. Youth solar ultraviolet radiation exposure, concurrent activities, and sun-protective practices: a review. Photochem Photobiol. 2005;81(6):1331-42.  

16. Green AC, Wallingford SC, McBride P. Childhood exposure to ultraviolet radiation and harmful skin effects: epidemiological evidence. Prog Biophys Mol Biol. 2011;107(3):349-55.  

17. Sohn M, Krus S, Schnyder M, Acker S. Performance, Safety and Sustainability – All in Tris-Biphenyl Triazine. SOFW Journal. 2021.  

18. Schalka S, de Paula Corrêa M, Sawada LY, Canale CC, de Andrade TN. A novel method for evaluating sun visible light protection factor and pigmentation protection factor of sunscreens. Clin Cosmet Investig Dermatol. 2019; 12:605-16.