A precise analysis of the relative contribution of UVA1 and visible light colour domains in solar light-induced skin pigmentation.

Background: Solar light induces or aggravates hyperpigmentation issues. The contribution of UVA1, as well as visible light (VL), especially high-energy blue-violet visible (HEV) light, is now clearly established.

Objectives: This work aimed at determining the relative contribution of UVA1, HEV and VL wavelength bands and their sub-domains in pigmentation induction.

Vitamin C Prevents Ultraviolet-induced Pigmentation in Healthy Volunteers: Bayesian Meta-analysis Results from 31 Randomized Controlled versus Vehicle Clinical Studies.

Repeated nonextreme sun exposures induce skin pigmentation by increasing melanin production and by oxidizing preexisting melanin and melanin precursors. This leads to skin disorders and skin color heterogeneity such as hyperpigmented spots. We assessed 31 randomized, controlled clinical trials to determine the potential of vitamin C to limit ultraviolet (UV) daylight-induced pigmentation, considering dose response and different skin type populations (Caucasian and Chinese).

Exposure to non-extreme solar UV daylight: spectral characterization, effects on skin and photoprotection.

The link between chronic sun exposure of human skin and harmful clinical consequences such as photo-aging and skin cancers is now indisputable. These effects are mostly due to ultraviolet (UV) rays (UVA, 320-400 nm and UVB, 280-320 nm). The UVA/UVB ratio can vary with latitude, season, hour, meteorology and ozone layer, leading to different exposure conditions.

In vivo persistent pigment darkening method: a demonstration of the reproducibility of the UVA protection factors results at several testing laboratories.

Background/purpose: The aims of the present studies were to check that persistent pigment darkening (PPD) method can produce accurate and reproducible results for high UVA protection factors (UVAPF) and to provide data on the variability between laboratories and on the influence of skin types.

Methods: The Japanese Cosmetic Industry Association (JCIA) PPD method was used to determine the UVAPF in different laboratories of different sunscreen formulations with increasing UVAPF. Two formulations were tested at seven independent laboratories and five products within two laboratories.