Sunscreen Products: A Highly Demanding Formulation Challenge

While a segment of consumers still does not protect itself effectively against the harmful effects of the sun, the demand for high SPF products is increasingly challenging sunscreen formulation. Sun protection products are no longer reserved for summer beach use only; daily sunscreens, inspired by Asian skincare routines, are gaining strong momentum. This trend is driving a growing number of sunscreen developments. However, sunscreens are not cosmetic products like any other, and their formulation requires a high level of expertise and control.

In sunscreen products, and according to regulatory frameworks, the ingredients that provide protection against UV radiation are UV filters, also referred to as sunscreen filters. The selection of these filters is critical to ensure the overall efficacy of the formula, which must provide broad-spectrum protection:  meaning adequate coverage in both UVB and UVA ranges. In Europe, the UVA protection factor must represent at least one third of the UVB protection factor, and the critical wavelength must be a minimum of 370 nm.

Under French regulatory authorities, in application of Regulation (EC) No. 1223/2009, a sunscreen product must contain one or more UV filters listed in Annex VI (the positive list) in order to claim sun protection. If no such filters are present, the product cannot make any sun protection claims. Only the ingredients listed in this annex are authorized as UV filters in Europe.

Whether organic/chemical or inorganic/mineral, all UV filters work by absorbing part of the UV radiation energy and converting it into imperceptible heat. Although mineral filters do reflect and scatter a small portion of UV radiation, they should not be considered a purely “physical shield,” as they are often portrayed.

The choice of UV filters depends on several factors, such as:

• The formulation format: some filters should be avoided when there is a risk of inhalation (sprays, powders). Not all filters are compatible with lightweight textures (fluids, daily sunscreens), especially when targeting high SPF levels;
• The target population: mineral filters are often recommended for sensitive skin, although recent organic filters show good tolerance profiles. For children, requirements regarding safety, tolerance, and broad-spectrum coverage are particularly stringent;
• The product range: organic or natural product ranges inevitably rely on mineral filters. Products positioned for darker skin tones tend to prioritize organic filters to avoid white cast and enhance UVA protection;
• The market(s) of commercialization: in some countries, sunscreens have a specific regulatory status, and authorized UV filters vary depending on local regulations;
• The brand’s formulation charter;
• Etc.

Even with a well-selected filter system, sunscreen performance does not rely solely on UV filters. To be effective, a sunscreen must form a continuous and stable film on the skin surface, in which UV filters are evenly distributed.

The first key challenge is therefore achieving a stable dispersion of UV filters. With organic filters, this is relatively easy to achieve. Mineral filters, however, are well known for their tendency to agglomerate and for the difficulty of achieving proper dispersion. This is precisely why DIY recipes based on zinc oxide are dangerous: it is impossible to properly disperse particles without industrial-grade equipment. Coating mineral filters, particularly titanium dioxide, to reduce particle reactivity, helps improve dispersion homogeneity and stability, as does encapsulation. In some countries, clean beauty trends are encouraging suppliers to engineer particles (especially zinc oxide) to improve dispersibility without coatings.

The choice of functional ingredients is then critical to obtain a uniform, adherent film on the skin. With increasingly strict regulations on microplastics and persistent misconceptions about synthetic ingredients, the selection of film-forming and texturizing agents has become more complex and limited. However, the performance of the final product on the skin is inseparable from its efficacy and the achievement of the expected SPF values. While naturality remains a strong consumer demand and suppliers are continuously improving ingredient profiles, it must not come at the expense of product performance. For example, water resistance is non-negotiable for products intended for beach use, as it directly impacts consumer safety.

SPF boosters have become essential to meet the demand for high protection factors while maintaining elegant textures. Some act as UV absorbers (which may be considered non-listed UV filters by regulatory authorities, potentially raising claim-related issues), while others improve filter dispersion or influence other parameters of the product film on the skin.

According to a recent FEBEA study, 59% of French consumers cite concerns about the health impact of sunscreen ingredients as a barrier to usage. These concerns often stem from preconceived ideas about UV filters, particularly chemical/organic ones. The now well-established clean beauty movement therefore strongly influences formula development, driving increased use of mineral filters, especially zinc oxide.

Minimizing environmental impact is also a major consumer expectation (no product can legitimately claim zero environmental impact, beware of greenwashing and misleading claims). However, limiting sustainability claims to the choice of UV filters alone is insufficient. Zinc oxide, often presented as “eco-friendly,” is classified as toxic to aquatic life under European CLP regulation. Furthermore, if present, its coating influences ecotoxicity and must be taken into account.

Similarly, opposing organic filters as environmentally harmful and mineral filters as inherently safer is an oversimplification. The ban of certain organic filters in specific regions has led to a general stigmatization of the entire category, despite the fact that newer filters show significantly improved ecotoxicological profiles. Conversely, some studies also demonstrate negative impacts of mineral filters on aquatic organisms, including coral reefs. It is therefore essential to establish the ecotoxicological profile of the filters used, but not only that. The entire formula must be assessed, as it is the final product whose overall environmental impact must be evaluated and tested.

Apart from a limited number of ISO-standardized tests, there is currently no harmonized protocol to assess the ecotoxicological profile of a cosmetic formula, particularly in marine environments. In this context, relying on toxicological expertise and case-by-case adapted testing strategies is highly relevant.

Once again, water resistance is a key criterion to limit the release of filters into aquatic environments and must be carefully optimized for ranges intended for swimming or water exposure. It is assessed according to ISO 16217 and ISO 18861 standards.

Whether in the choice of UV filter systems or functional ingredients, sunscreen products are often subject to contradictory consumer expectations. Yet, with their unique status at the crossroads of cosmetics and public health, there is no margin for error in their formulation. Sunscreens are among the most complex cosmetic products to develop due to the multiple constraints involved. This level of complexity makes a structured PLM approach indispensable: solutions like Coptis provide a single source of truth that enables R&D teams to manage formulation, regulatory, and performance requirements with consistency, speed, and confidence. Nevertheless, they remain a highly stimulating field for exploration and innovation, driven by strong demand for increasingly convenient galenic forms and more targeted positioning.