​It is known that blue light is capable of inducing DNA oxidation reactions. However, this process remains much less efficient than the formation of photoproducts triggered by the absorption of ultraviolet (UV) radiation.
The researchers sought to find out if, like UVA, blue light could not degrade the enzymes responsible for eliminating photoproducts induced by UV. For this purpose, they exposed human epidermis reconstituted in vitro to blue light then to UV. They then looked at the effectiveness of the repair of the photoproducts after 48 hours.

​The results clearly show that exposure to blue light leads to poorer repair. They then repeated the experiment by applying sunscreen containing a photoprotector against blue light to the skin models. In this case, DNA repair is almost normal.

These data provide important information on the toxicity of sunlight, while opening new avenues in terms of photoprotection.​