More ingredients may mean more allergens, in sunscreens: A screening analysis of commonly accessed sunscreens in India

INTRODUCTION

Sunscreens are important tools for dermatologists treating skin of color (SOC) individuals. Post-inflammatory hyperpigmentation (PIH), a dreaded complication of procedural treatments and naturally occurring conditions such as acne and trivial trauma, is reported in up to 58.2% of individuals.^[1] The use of sunscreens post-laser treatments has been known to reduce PIH.^[2,3] As a product that is left on, at times even on broken skin for prolonged periods of time, the potential for contact allergy with sunscreen use remains a concern. Keyes et al. noted the presence of allergens in all of the sunscreens evaluated by them.^[4] Acknowledging the rapid increase in sunscreen use, we aimed to evaluate the presence of known allergens in topical sunscreens available in India.

MATERIALS AND METHODS

Sunscreens were selected using the search terms “sunscreen,” “sun screen,” “sunscreens,” and “sunscreen in India” across commonly used online marketplaces, including Amazon, Flipkart, SkinStore, Tata 1 mg, Nykaa, Purplle, and SkinStore.in and on Google Search and listings within the first 10 pages from each source included. Sunscreens without approved ultraviolet (UV) filters were excluded. Allergens concluded to be more prevalent (i.e., more than 1%) by the North American Contact Dermatitis Group (NACDG) core data (2019–2020) were considered high-prevalence allergens while allergens linked to allergic contact dermatitis in the literature but not listed by the NACDG were classified as low prevalence allergens.^[4-7] Totally, 135 allergens were taken up for screening including 48 high prevalence and 87 low prevalence allergens.

RESULTS

We screened a total of 1048 sunscreens of which 918 sunscreens were eligible for analysis, comprising 159 mineral, 330 chemical, and 429 hybrid sunscreens, the latter containing both chemical and mineral UV filters. Allergens were noted in 899 (98%) sunscreens of the total sunscreens tested, 330 (100%) among chemical sunscreens, 143 (89.9%) among mineral sunscreens, and 426 (99.3%) among hybrid sunscreens, [Table 1]. The most common high-level allergens and the most common low-level allergens in our study were fragrances and octinoxate, respectively.

The number of allergens in a sunscreen formulation increased with an increasing number of ingredients, [Figure 1]. Mineral sunscreens contained significantly fewer ingredients and allergens compared to chemical and hybrid sunscreens (P < 0.001). In turn, chemical sunscreens had fewer ingredients than hybrid sunscreens (P = 0.03), but the number of allergens did not significantly differ between them. Sun protection factor (SPF) values did not correlate with the number of allergens. A higher number of ingredients correlated with higher SPF for hybrid sunscreens, but not for mineral or chemical sunscreens.

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Figure 1:

Graph representing an increase in number of allergens with increasing number of ingredients.

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DISCUSSION

Selecting a sunscreen that balances high effectiveness with low allergenicity is essential for the general population. To accomplish this, sunscreens must be assessed not only for their SPF and protective attributes but also for their ingredient composition, focusing on potential allergens.

Allergies to sunscreens have been increasingly reported in recent times, potentially reflecting a rise in global sunscreen use, with up to 95%^[8-10] of positive photopatch tests being attributed to sunscreen filters, notably oxybenzone. The list of potential allergens noted in sunscreens based on current literature are listed below [Table 2]. In alignment with previous studies, fragrances emerged as the most common high-prevalence allergens in our dataset, identified in 98% of sunscreens. Literature from New Zealand^[11] and other international studies^[4] similarly reported fragrances as the predominant allergens in sunscreens. Our study identified octinoxate, a chemical UV filter, as the most common low-prevalence allergen. In contrast, previous literature highlights other chemical UV filters, such as octocrylene, oxybenzone, and avobenzone, as predominant low-prevalence allergens.^[4] Our study notes a high prevalence of commonly acknowledged allergens in sunscreen products accessed by the Indian public, higher for chemical and hybrid sunscreens compared to mineral sunscreens. The increase in allergen number with increasing ingredient count is highly interesting, considering chemical sunscreens employed more ingredients for similar SPF as mineral and hybrid sunscreens. For the same SPF, choosing a sunscreen with a lesser number of total ingredients may translate into choosing a sunscreen with a lesser number of allergens.

An impaired epidermal barrier post-fractional laser resurfacing was shown to be associated with increased contact sensitization to octocrylene, compared to those with intact skin.^[12] However, early use of sunscreens is important to reduce PIH after fractional laser treatments.^[3] This raises a dilemma in deciding between sun protection and allergen avoidance for the dermatologist treating SOC patients. To choose sunscreens with lesser allergenicity, physicians may simply consider sunscreens with a lesser number of ingredients when advising patients on these special care circumstances, such as post-fractional laser ablation. Further, mineral sunscreens may be advisable for sensitive skin, in keeping with earlier studies.^[8]

CONCLUSION

With an exponential rise in sunscreen awareness and use, it is important to remain vigilant for contact dermatitis to sunscreens. While it would be very useful to know which of these high- or low-level allergens are relevant in modern-day formulations in Indian skin types in prevalent weather through patch testing and photopatch testing, our study provides a good starting point to guide better product selection for consumers and dermatologists alike.