It is well-known that the ultraviolet (UV) radiation emitted by the sun can cause damage to the skin. UV radiation can be separated into three regions: UVA, UVB and UVC. These regions are defined by different wavelengths: UVA between 320–400 nm, UVB 290–320 nm, and UVC 100-290 nm. Historically, the focus of sun care research has been toward designing filters to protect from UVB radiation since it penetrates the epidermal layers and has been proven both to cause sun burn and play a role in the development of skin cancer.
In more recent years, research has shifted toward protecting the skin from UVA radiation. UVA accounts for approximately 95% of the UV radiation reaching the earth’s surface and is known to penetrate the epidermal and reach the dermal layers of the skin. It has also been linked to skin aging and the formation of skin cancer. Protection from UVC radiation is not required because the high energy shorter wavelengths of UV radiation are absorbed by the ozone layer and do not reach the earth’s surface.
There are numerous approaches to designing broad-spectrum, i.e., UVA and UVB, sun protection formulations. The first is to use organic or chemical UV absorbers such as butyl methoxydibenzoylmethane (BMDM) and octocrylene; however, this type of system cannot be labeled “natural” and with the consumer market focused on eco-friendly products, alternative solutions are required. In addition, the combination of organic filters have regulatory and use restrictions that vary across the globe. This makes it difficult for formulators to produce sun care formulations using only organic UV absorbers.