The effect of ultraviolet radiation on the anti-inflammatory effect of filters.

A certain number of filters have notable anti-inflammatory properties with percentage inhibition of PMA-induced edema in mice at over 70%. The question arose as to whether this effect was likely to continue after UV irradiation. It can be noted that 7 filters retain an equivalent anti-inflammatory effect before and after 2h of irradiation in a Suntest device (650 W/m(2)). For 9 filters, the anti-inflammatory effect decreases and for 5 filters, the anti-inflammatory effect increases. Various behaviors should be noted. 3 groups of substances can be distinguished: such as phenylbenzimidazole sulfonic acid which loses its anti-inflammatory character after irradiation (the percentage inhibition falls from 80 to 44%), oxybenzone which retains a constant anti-inflammatory character (89% inhibition before and after irradiation and also octyl methoxycinnamate which becomes very anti-inflammatory (with a percentage inhibition of 93%). The same phenomenon is observed in the case of commercial products. This should be made known as it can have a considerable impact on the results which are displayed on the packaging of sun products.

Sunscreen products: what do they protect us from?

Whereas for fifty or so years acquiring a tan has been the trend for aesthetic reasons relating to current beauty criteria, the health authorities are now advocating vigilance in this area, prompted by the knowledge of the harmful effects of the sun, especially from its ultra-violet rays. In the European Union, sunscreen products are considered cosmetics and tests on their effectiveness can be performed in vivo or in vitro to determine four effectiveness indicators: the SPF (Sun Protection Factor), the PF-UVA (UVA Protection Factor), the SPF/PF-UVA ratio and the critical wave length. It is the erythemal SPF which is measured in the vast majority of cases: it can therefore be confirmed that sunscreen products protect us from sunburn under good conditions of use. We thought it would be interesting to calculate other indicators to assess protection against non-melanoma skin cancers (NMSC) and to quantify the effectiveness of the product against UVA1 or UVA2. To characterize the products tested, we have determined in vitro different SPF and PF-UVA values, by using not just the erythemal weighting factor but also the weighting factor relating to the non-melanocytic skin cancer (SPF(cnm) and PF-UVA(cnm)), by getting away from any weighting factor (SPF(m) and PF-UVA(m)) and lastly, by varying the integration limits to quantify the effectiveness of the tested product in the UVB (290-320 nm), UVA1 (340-400 nm) and UVA2 320-340 nm) fields. In this way, and using these new indicators, we have been able to qualify eleven commercial products-ten cosmetic products and one medical device. It can be interesting to take into account the non-melanocytic skin cancer protection in order to qualify the sunscreen products.