Photoprotection: how to preserve skin from the aggressive sunlight?

Sunscreens are an integral part of protection against aggressive solar radiation. The modern market of cosmetic products offers a wide range of different sunscreen products containing a set of components that help protect the skin from the harmful effects of solar radiation.

It should be noted that there are two types of UV radiation: UFA and UVB. UVA radiation does not cause skin burns, but it can penetrate deeper into the layers of the skin. UVB radiation, on the contrary, causes burns, but does not penetrate deep into the skin.

The main component of sunscreen is UV filter - a substance that can absorb or reflect the ultraviolet portionof solar radiation, the effect of which can lead to premature aging and the occurrence of various skin diseases.

The effectiveness of UV filters is measured by the solar protection factor (on the label of cosmetics - Sun Protective Factor (SPF) and is the ratio of the minimum dose of UV radiation that causes redness of protected skin to the minimum dose of UV radiation that causes redness of unprotected skin.

For example, SPF 15 of sunscreen means that, with its use, the dose of UV radiation necessary for the appearance of erythema (severe reddening of the skin) should be 15 times higher than without the use of a cream.

There are two types of UV filters - physical and chemical. The first are mineral substances that are capable of reflecting the Sun rays. Most often, the cosmetics of this group include titanium dioxide and zinc oxideFor example, in the composition of products of La Roche-Posay with SPF 30). The disadvantages of these substances include white traces, which they leave on the skin. Physical filters do not cause allergic reactions, which is undoubtedly their advantage. Often, titanium dioxide is used in combination with carnauba wax, which ensures the optimum viscosity of the cosmetic and increases its effectiveness.

The second group of substances - chemical filters - is capable of absorbing the energy of UV radiation and turning it into a thermal one. These filters most effectively protect the skin from UVB radiation. By chemical structure, they can be divided into several subgroups:

1. Paraaminobenzoic acid derivatives (PABA). PABA ether is most oftenly used in this group, the trade names of which are represented by Escalol 507, Eusolex 6007 and Padimate O. The maximum permissible concentration (MPC) of this substance is 5%.
2. Derivatives of salicylic acid. They include, for example, homomentyl salicylate (Homosalate). This group of substances is actively used in cosmetic products manufactured in the USA.
3. P-methoxycinnamic acid derivatives (Parsol MCX). However, in some studies increased sensitivity of the skin to this component was noticed.
4. The derivatives of camphor are also distinguished by their ability to cause allergic reactions.

There are also wide-range chemical filters that protect the skin from UFA and UFB radiation. They include the following groups:

1. Benzophenones 3, 4, 5
2. Phenylbenzotriazole sulfonic acid (Mexoryl® XL, Tinosorb® M, Tinosorb® S) A mixture of these acids is part of the composition of the sunscreens produced by La Roche-Posay with SPF 50 andL'Oreal Paris)

References:

1. New Cosmetology - Margolina AA, Hernandez EI - Practical Manual Volume 1