While UV protection is obviously the most important feature of sunscreens, increasing numbers of hybrid products are now presenting sun protection alongside skin care and even colour cosmetic claims. This is due in part to growing consumer awareness that sun exposure is not limited to beach holidays; it is the episodic, everyday exposures to the sun over years which put both the skin’s health and its appearance at risk.
Sunscreens increasingly offer additional benefits over simple protection from sunburn. However, despite sunscreens being among the most highly regulated of all personal care products, guidelines about the protection they should offer differ across many countries. As a result, it is no longer enough that global sun protection formulations meet a required SPF; they must now also meet varied UVA protection standards. This increasing pressure for UVA protection along with a growing list of demands from ever more discerning consumers means that greater restrictions have been placed upon the global formulator.
UV regulations
Heightened consumer awareness of the damaging and ageing effects of ultraviolet (UV) radiation has placed greater strain upon formulators of sun protection products. UV radiation is separated into three different categories according to their different wavelengths. UVC radiation (100 nm-290 nm) does not reach the Earth’s surface since it is absorbed by the ozone layer. Previously the focus of research in sun protection products has been the design of filters to protect from UVB radiation (290 nm- 320 nm).1 UVB rays are able to penetrate into the epidermal layers of the skin and contribute to the development of skin cancer and result in the most visible skin damage; sunburn, or erythema.2 Of the UV radiation reaching the Earth’s surface, UVA wavelengths (320 nm-400 nm) account for 95%.3 For many years UVA radiation was thought not to cause any skin damage, however it is now known that these longer wavelengths are able to reach the dermal layers of the skin, penetrating further than UVB rays. This contributes to the development of skin cancer and is also linked to premature ageing of the skin. This has resulted in more focus being placed upon providing UVA protection, primarily in sunscreens, although increasing numbers of skin care products are now also providing UVA protection. Thus the creation of globally approved formulations though can be a frustrating challenge, since UVA protection and labelling requirements vary between regions. In Europe, Colipa recommends that the UVA Protection Factor (UVAPF) of a sunscreen should be at least one third of the labelled SPF. In addition, the critical wavelength of the product should be at least 370 nm.4 The FDA also requires that sun protection products in America meet this critical wavelength.5 Asia meanwhile uses an in vivo Persistent Pigment Darkening (PPD) method to assign a PA label to a product, based upon its UVAPF. There are three PA rankings available, with PA+ corresponding to a product with a UVAPF of between 2 and 4, PA++ a UVAPF of between 4 and 8, and PA+++ products offering the highest protection, with a UVAPF of greater than 8. While vital in sunscreens, UVA protection is not solely related to these applications. In the US, if a daily skin care product has an SPF claim of 15 or above, as with a sunscreen, it must meet the critical wavelength of 370 nm. Meanwhile, UVA protection in skin care is a growing trend in Europe and an established consumer need in Asia. As a result, providing UVA protection in formulations is now crucial. With such varied requirements for UVA protection in a global formulation, numerous strategies have been developed to ensure that the global UVA requirements are met. One approach combines organic, or chemical, UVA and UVB filters to provide high SPF broad spectrum protection. However despite the Encyclopaedia of Ultra Violet Filters listing 53 organic UV filters that are approved in at least one country or region, only nine of these are permitted for global use.6 Additionally, consumer concerns over exposure to excessive chemicals and the perception that chemical sunscreens can lead to skin irritation makes formulating a globally compliant, organic only sun protection product that offers additional skin benefits difficult. Another solution commonly employed by global formulators uses a combination of organic and inorganic, or physical, UV filters. However, incompatibilities between ingredients and the global Intellectual Property (IP) status of some UV filters can complicate the formulation process. The final method combines the physical UV filters titanium dioxide (TiO2) and zinc oxide (ZnO). Often referred to as ‘nature identical’ minerals, these physical UV filters are the most natural sunscreens available, but despite both of these filters currently being approved for global use in cosmetics, the future status of ZnO as a UV filter in Europe is yet to be formally clarified. To overcome these difficulties, it would be desirable to use the globally approved physical filter, TiO2, as the sole UV active. This has historically not been a viable solution, since conventional forms of TiO2 provide excellent protection from UVB rays, but fail to meet the current global standards for UVA protection.
Protection across the spectrum
The award winning SolaveilTM SpeXtra range of TiO2 dispersions from Croda has been developed to offer the same SPF efficacy as conventional grades of TiO2 while providing unprecedented UVA protection. A carefully controlled thermal processing method is used to produce the TiO2, giving the optimal particle size and shape for UVA efficacy while controlling particle size distribution. The result is a material that offers much enhanced UVA attenuation coupled with the high SPF efficacy typical of conventional TiO2 sunscreens, without excessive whitening in the final product. A new addition to the Solaveil SpeXtra range, Solaveil XT-40W, uses water as the carrier medium to offer formulation flexibility. This is a major benefit to formulators as it allows the aesthetics of emulsions to be adjusted by selecting emollients that deliver sensorial requirements, offering the potential for additional skin care claims. Furthermore, a synergistic effect can be achieved through the combination of Solaveil XT-40W (now referred to as ‘the new dispersion’), with oil-soluble organic filters. The resulting biphasal distribution of actives boosts SPF while maintaining the required broad spectrum claims. This allows less loading of phases than in either organic or inorganic only systems, with increased flexibility for emollients to solubilise organic filters in the oil phase. Additionally, more cost effective formulations can be created using lower levels of the new dispersion than would be needed in an inorganic only system, which can also result in improved transparency.
Natural BBeauty
Alongside the regulatory requirements, busy consumers are becoming more demanding; multifunctional products that ultimately save consumers time and money in their daily routines are growing in popularity. This is evident in the boom in popularity that BB creams are experiencing around the world. BB, or Blemish Balm, creams were first developed in Germany as an intensive after-treatment for those who had undergone skin surgery. Offering the benefits of skin care and make-up in a single application, these were quickly adapted as an all-in-one beauty and skin care product. Originally popular in Asia, where they became known as ‘the Korean actress’s secret’, BB creams are beginning to grow in popularity in Europe, with consumers drawn to the many claims they make, from concealing and moisturising to firming and UV protection. Research has shown that combining Solaveil SpeXtra with iron oxide pigments creates an ideal colour for tinted moisturisers, foundations and BB creams. The formulation below showcases the new dispersion in the Miracle Skin Protector BB Cream, demonstrating that natural colour cosmetics can be created without compromising elegance or performance. Mild enough for everyday use while meeting the global UVA requirements, this formulation is predicted to be classified as PA+++ for protection against skin darkening, or hyperpigmentation. Optimised for daily wear, the combination of emollients and rheology modifiers have been carefully selected to create a light, spreadable texture and leave a pleasantly smooth skin feel. Meanwhile the new dispersion as the single UV active creates a physical shield to reduce UV-induced radicals within the skin, providing protection against premature signs of ageing. With increased media activity and consumer awareness placing greater importance upon green formulations, as an added benefit, this formulation is based entirely on naturally derived ingredients. The use of NatraGem E145 and Span 20 emulsifiers, along with hydrocolloid thickeners, allows for a cold mix system which can further strengthen the formulation’s green credentials.
Conclusion
As busy consumers look to minimise the time they spend on their daily beauty regime, multitasking products that cover a variety of claims are becoming the norm. With increasing numbers of sunscreens now featuring skin care and colour cosmetic claims alongside UV protection, the challenge of meeting the global requirements for UVA protection is paramount. The Solaveil SpeXtra range from Croda allows the creation of high SPF sunscreen products without compromising UVA protection. The use of the novel waterbased dispersion, Solaveil XT-40W, offers the formulator greater flexibility, as the careful selection of emollients, thickeners and oils allows greater control over the aesthetics of their formulation. Solaveil XT-40W acts as a physical shield for superior UVA and UVB efficacy and can be used as a single active, exhibiting exceptional synergy in combination with organic UV filters.
References
1 COLIPA. International sun protection factor test method, May 2006. 2 Diffey BL. Solar ultraviolet radiation effects on biological systems. Phys Med Biol; 36: 299-328. 3 Nelson CG. Photoprotection, In: Shaath NA ed. Sunscreens: regulations and commercial development 3rd edn. New York: Taylor and Francis, 2005: 19-43. 4 European Commission recommendation of 22 September 2006, on the efficacy of sunscreen products and the claims made relating thereto. Official Journal of the European Union 2006; 26: L265/39-L265/43. 5 Food and Drug Administration, Final rule: Labelling and effectiveness testing: sunscreen drug products for over-the-counter human use. Federal Register 2011; 76 (117). 6 Shaath NA. The encyclopaedia of ultra violet filters. Allured Publishing Corporation, 2007.
Picture Credit: www.morguefile.com
