The launching of cosmetics’ active ingredients and products on the world market is a dynamic process, one in a state of constant expansion and renewal.
A part of this is the search for methodologies that protect and work in scientific tandem with products and substances that promote skin homeostasis and that can slow down and reverse skin sun-ageing. This is an area of constant research and development in the fields of cosmetics and dermatology.
In addition to the less than aesthetic changes brought on by the sun’s rays, solar radiation is related to the development of skin cancer, a result of radiation’s genotoxic and immunosuppressive effect.
It has been shown that ultraviolet radiation (UV) is the main contributory factor to tissue damage and skin aging. However, infrared radiation (IR) is cited as an aggravating factor in this process, adding to the effect UV radiation has on physiological changes in the skin. UV radiation accounts for only 6.8 % of solar radiation, while IR radiation and visible light radiation (VL) make up 54.3 % and 38.9 % of solar energy, in turn.
IR and VL radiation have come to the attention of the scientific community following the inclusion of histological alterations similar to those brought on by chronic exposure to UV radiation.
IR radiation can result in two types of effects: one thermal (either beneficial or harmful, depending on the amounts) and the other oxidative damage, this latter with more of a concentration in the band closest to IR. IR radiation (760 –1500 nm) penetrates deeper into the skin, as 35% of the radiation is concentrated in the epidermis, 48% in the dermis and 17 % in the subcutaneous tissue.
Something commonly experienced after exposure to IR radiation is the decreased synthesis of major dermal proteins collagen and elastin, proteins essential in skin support, and this results in the premature signs of skin aging.
High amounts of VL can cause erythema (via heat production) and hyperpigmentation (via melanin synthesis).
The authors of these studies suggest that VL induces a reaction within the chromophores that produces heat and promotes eumelanin synthesis. This then results in increased heat production, which promotes vasodilation and the onset of erythema.
As the above shows, there are various factors that contribute to skin sun-aging. However, there is no evidence so far of sunscreens capable of physically or chemically protecting against IR and LV radiation. In this sense, discovering mechanisms adjacent to the protective mechanisms via absorption, reflection and dispersion of light is an important challenge to be overcome. It is one that leads us to ask questions and reflect on the concept of “broad spectrum,” seeking to minimize the effects caused by sun exposure.