Chemical or mineral sunscreen: which one should be used for your skin?

To protect the skin from the harmful effects of the sun, both UVB and UVA rays, there are two types of UV filters used in sunscreens: chemical filters and physical filters. Strictly regulated in Europe, only 27 UV filters are authorised by the European cosmetic regulation, all evaluated by the European Scientific Committee for Consumer Safety (SCCS).

• Physical filters.

  Composed of an assembly of mineral microparticles, these sunscreens with a particle size of 200 to 500 nm are capable of diffracting and reflecting UV rays in the UVB and UVA spectrum and visible light through a mechanical action similar to an opaque barrier, by creating a film of inert metallic particles.

  Benefits : More tolerant, they are less allergenic than sun creams containing organic filters and do not cause sensitisation reactions. Indeed, it has been demonstrated that sunscreens using only inorganic filters do not penetrate further than the corneal layer and the upper layers of the epidermis. Moreover, only mineral sun protection products can be labelled as organic. Finally, these molecules are photostable.

  Drawbacks : Sunscreens composed of mineral filters tend to leave white traces on the skin during application, due to their opaque nature. However, this white appearance disappears gradually during application. In order to improve these organoleptic characteristics of products formulated with physical filters, a formulation effort has been made: mineral filters now exist in nanoparticle form. However, already banned in spray form, the presence of nanoparticles could potentially cause toxic effects on marine flora, particularly on phytoplankton, not to mention the fact that they could cause a trans-epidermal passage phenomenon resulting in potential toxicity.

• Chemical filters.

  Composed of chemically modified carbon compounds, these sunscreens create a thin filtering film that directly absorbs solar radiation in place of the skin, due to the presence of a chromophore group. They then transform UV light into fluorescent radiation or dissipate it through internal conversion mechanisms, releasing the energy in the form of a small amount of heat.

  Benefits : Being more fluid, they leave less of a "white" effect on the skin for a more even application.

  Drawbacks : Due to their mechanism of action, chemical filters can penetrate the skin barrier and thus may induce a minimal risk of allergy (redness, irritation...), especially in individuals with sensitive and atopic skin. Moreover, some UV filters are subject to controversy as they are suspected of acting as endocrine disruptors. However, we lack perspective and studies regarding their potential harm which remains to be proven. The doubts do not concern all chemical filters. In the meantime, it is better to apply the precautionary principle and avoid suspect compounds, such as theoctocrylene, oxybenzone (INCI: Benzophenone-3), thehomosalate, theavobenzone (INCI: Butyl Methoxydibenzoylmethane), the sulisobenzone (INCI: Benzophenone-4), the padimate-O (INCI: Ethylhexyl Dimethyl PABA), the PABA, etc. Finally, some chemical filters could also have an impact on the environment: they would be toxic to marine fauna and corals.

However, whether the cream is mineral or chemical, there is no difference in terms of protection efficacy against UV rays.

Although infrequent and subjective, tingling, redness, and heat sensations are the most common complaints associated with chemical sunscreens. However, individuals prone to photodermatoses and eczema may be predisposed to developing a photo-allergy. Consequently, reactive, sensitive, or even sun-allergic skin should opt for sunscreens based on mineral filters (zinc oxide and titanium dioxide) as a precaution, as they are generally better tolerated. Delicate and sensitive, sun creams with sun filters are also recommended for children.

Most of the time, a sun protection product combines both filters to cover the entire solar spectrum. Without nanoparticles, our sunscreen products combine mineral filters with chemical filters for reasons of application comfort and texture.