The sun--our friend or foe?

• Published in: Annals of Agricultural and Environmental Medicine 2012, Vol.19 (4), p.805-809
• Main Authors: Osmola-Mańkowska, Agnieszka, Silny, Wojciech, Dańczak-Pazdrowska, Aleksandra, Olek-Hrab, Karolina, Mańkowski, Bartosz, Osmola, Krzysztof, Hojan-Jezierska, Dorota, Kubisz, Leszek
• Format: Article
• Language: English
• Subjects: Biological effects; Carcinogenesis; Chronic effects; Chronic exposure; Contact dermatitis; Environmental hazards; Humans; Hypersensitivity; I.R. radiation; Immunosuppression; Infrared radiation; Irradiation; Photosensitivity; Photosynthesis; Phototherapy; Phototherapy - adverse effects; Skin - radiation effects; Skin cancer; Skin diseases; Skin Diseases - etiology; Skin Diseases - pathology; Skin Diseases - physiopathology; Skin Diseases - prevention & control; Skin Physiological Phenomena - radiation effects; Squamous cell carcinoma; Sunburn & sun tanning; Sunlight; Sunlight - adverse effects; Tanning; Ultraviolet radiation; Vitamin D; Vitamin D - biosynthesis; Vitamin D - radiation effects
• ISSN: 1232-1966; 1898-2263

Sunlight is the major source of the energy on Earth. Visible light, ultraviolet and infrared radiation are necessary to sustain life on our planet. However, besides the range of positive effects, such as photosynthesis in plants, warmth, vision, and synthesis of vitamin D, sunlight may also be responsible for negative biologic effects - sunburn, induction of photodermatoses or carcinogenesis. Ultraviolet is regarded as the major environmental, physical hazard to the human skin. The acute clinical effect of ultraviolet involves melanogenesis, i.e. tanning, which protects from sunburn if exposure is overdosed. A single exposure, as well as acute suberythemal irradiation, suppresses sensitization of the contact hypersensitivity. The chronic biological effects are photoageing and skin cancer, especially squamous cell carcinoma (SCC). Vitamin D synthesis is regarded as a benefit of natural acute and chronic exposure to ultraviolet. Ultraviolet also plays an important role in aetiology of the group of disorders characterized by photosensitivity. On the other hand ultraviolet is a known inducer of immunosuppression in the skin; therefore, phototherapy is a therapeutic option for patients with activation of dermal immunity. Without sunlight, the existence of life on Earth is not possible. On the other hand, UVR radiation is regarded as representing one of the most important environmental hazards for human skin. For a better understanding of the mechanisms related to the influence of UVR on human skin, and the most dangerous chronic effects of carcinogenesis, it is necessary to undertake some protective activities. Moreover, UVR may become our ally in the treatment of selected skin disorders.