Sunlight

Anti-Pollution Matrix > Pollutants > Pollutant list > Sunlight

Explanation

The skin, as the primary barrier between the environment and the body, is exposed to solar radiation on a daily basis. Ultraviolet (UV) radiation accounts for 3 - 7% of the total solar spectrum and in dermatological photobiology is divided into the following three spectral regions: UVA (320 - 400 nm), UVB (290 - 320 nm) and UVC (200 - 290 nm). While UVC is completely filtered in the stratosphere and does not reach the Earth's surface, the UVA (90 - 95%) and UVB (5 - 10%) fractions are biologically effective in the skin [1]. UV light generates the most radicals, followed by irradiation in the visible (VIS) and near infrared (NIR). About 60% of all radicals are generated by UV, and the remaining 40% of all free radicals are formed by VIS and NIR. VIS and NIR irradiation penetrate deeper into the skin than UV light, promoting increased radical formation in deeper skin layers [2].

 

Impact on the skin

Excessive doses of solar radiation lead to the formation of free radicals (reactive oxygen species, ROS). ROS must be tightly controlled to prevent their uncontrolled accumulation in the cell (oxidative stress); otherwise, they are harmful to metabolic processes: increased oxidation of cellular components such as membranes, lipids, proteins, and nucleic acids (genotoxicity) may result and increase cellular and tissue damage. In terms of skin physiology, ROS are significantly involved in the development of erythema, sunburn, inflammatory skin diseases, immunosuppression, skin cancer/tumorigenesis, and premature skin aging. Despite the large number of skin-friendly, UV-absorbing and reflective sunscreens, the incidence of skin cancer has been increasing sharply nationally and internationally for decades [3].

 

Measures

UV-absorbing and reflective sunscreens use two different types of UV filters: chemical and physical. Antioxidants can also be applied to counteract the oxidative stress induced by sunlight (UV, VIS, and NIR).

 

Detection methods of the effects

Electron spin resonance (ESR) spectroscopy is a sensitive non-invasive method for detecting radical formation in tissues (in vivo/ex vivo), cells (in vitro) as well as (body) fluids. The use of different ESR probes allows the quantification and characterization of radicals, e.g. after sun exposure.

 

Literature

[1] J. D'Orazio, S. Jarrett, A. Amaro-Ortiz, T. Scott, UV radiation and the skin, Int J Mol Sci, 14 (2013) 12222-12248, doi: 10.3390/ijms140612222
[2] S.B. Lohan, R. Muller, S. Albrecht, K. Mink, K. Tscherch, F. Ismaeel, J. Lademann, S. Rohn, M.C. Meinke, Free radicals induced by sunlight in different spectral regions - in vivo versus ex vivo study, Exp Dermatol, 25 (2016) 380-385, DOI: 10.1111/exd.12987.
[3] S. Pillai, C. Oresajo, J. Hayward, Ultraviolet radiation and skin aging: roles of reactive oxygen species, inflammation and protease activation, and strategies for prevention of inflammation-induced matrix degradation - a review, Int J Cosmet Sci, 27 (2005) 17-34, DOI: 10.1111/j.1467-2494.2004.00241.x