Prevention of ultraviolet-induced skin pigmentation
Article first published online: 20 SEP 2004
Photodermatology, Photoimmunology & Photomedicine
Volume 20, Issue 5, pages 243–247, October 2004
How to Cite
Moyal, D. (2004), Prevention of ultraviolet-induced skin pigmentation. Photodermatology, Photoimmunology & Photomedicine, 20: 243–247. doi: 10.1111/j.1600-0781.2004.00111.x
- Issue published online: 20 SEP 2004
- Article first published online: 20 SEP 2004
- Accepted for publication 30 June 2004
- skin pigmentation;
- UVA protection
Background/purpose: Exposure to ultraviolet (UV) radiation increases skin pigmentation and usually results in an even darkening of the skin. However, it may also occasionally lead to the development of hyperpigmented lesions due to a local overproduction of pigment. Skin pigmentation is induced both by UVB and UVA rays.
Methods: The in vivo protection by sunscreens against pigmentation was studied using the determination of a level of protection against pigmentation based on the standardized sun protection factor (SPF) test method. The method includes delayed UVB and UVA pigmentations. The level of prevention against pigmentation was determined 7 days after exposure to solar-simulated radiation by visual assessment. It was calculated using the ratio of the minimal pigmenting dose on protected skin to the minimal pigmenting dose on unprotected skin. Broadspectrum UVB/UVA filters, Mexoryl®SX and Mexoryl®XL, and complete formula were tested.
Results: Protection against pigmentation correlates with the concentration of Mexoryl®SX. The levels of protection obtained show a synergetic effect of Mexoryl®SX when associated with Mexoryl®XL. When different products having the same SPF (same protection against erythema) and different levels of UVA protection are compared, only sunscreen products with a high level of UVA protection show a similar level of protection against sunburn and pigmentation. Products with low UVA protection have a lower capacity of preventing induced pigmentation compared with their efficacy against erythema.
Conclusions: These studies have evidenced that SPF determination was not sufficient to account for the efficiency in preventing pigmentation and that UVA protection was an essential part of this prevention.