Skin type differences in sun‐induced oxidative stress

Abstract

Excessive solar (sun) exposure, especially ultraviolet radiation, can lead to sunburn and increased damage to cells, called oxidative stress. This can cause skin damage such as inflammation, premature skin aging and tumour development. Statistics from the U.S. National Cancer Institute show that the number of new cases of melanoma and non‐melanoma skin cancer are rising every year. Therefore, it is important to understand the negative effects of solar radiation in skin. Beside the ultraviolet light, the visible and near infrared regions of the solar spectrum induce oxidative stress in fair skin types but data about the effects in darker skin types are missing. A German study addressed the distribution of oxidative stress in dark skin during solar irradiation and compared the results to those of fair skin types. Free radicals are a marker for (i.e. sign of) oxidative stress. The scientists measured the formation of free radicals on volunteers during solar irradiation, using technology called electron paramagnetic resonance spectroscopy. The authors found that darker skin was better protected against ultraviolet radiation than fair skin. However, darker skin types showed significantly more oxidative stress during near infrared irradiation compared to fair skin types. The oxidative stress in the near infrared is at least as high as in ultraviolet and visible spectral regions and could cause skin damage in darker skin. The results show that individuals of darker skin might need a different type of sun protection than those of paler skin to avoid long term damage by solar radiation.