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Sunbaker, by Max Dupain. Exposure of skin to ultraviolet radiation from sunlight presents both positive and negative health effects. On the positive side, UV exposure enables the synthesis of vitamin D 3, which is essential for bone health [1] and potentially plays a role in inhibiting certain cancers.
Given the causal relationship between sun exposure and AK growth, they often appear on a background of sun-damaged skin and in areas that are commonly sun-exposed, such as the face, ears, neck, scalp, chest, backs of hands, forearms, or lips. Because sun exposure is rarely limited to a small area, most people who have an AK have more than one. [10]
The skin response resembles an exaggerated sunburn. The involved chemical may enter into the skin by topical administration, or it may reach the skin via systemic circulation following ingestion or parenteral administration. The chemical needs to be "photoactive," which means that when it absorbs light, the absorbed energy produces molecular ...
Vitamin D has a wide range of positive health effects, which include strengthening bones [50] and possibly inhibiting the growth of some cancers. [51] [52] Sun exposure has also been associated with the timing of melatonin synthesis, maintenance of normal circadian rhythms, and reduced risk of seasonal affective disorder. [53]
Extrinsic ageing of skin is a distinctive declination process caused by external factors, which include ultra-violet radiation, cigarette smoking, air pollution, among others. Of all extrinsic causes, radiation from sunlight has the most widespread documentation of its negative effects on the skin.
Subsequent studies further defined the wavelengths most efficient for germicidal inactivation. In 1892, it was noted that the UV segment of sunlight had the most potent bactericidal effect. [36] [37] Research conducted in the early 1890s demonstrated the superior germicidal efficacy of UV-C compared to UV-A and UV-B. [38] [39] [40]
Photoprotection is the biochemical process that helps organisms cope with molecular damage caused by sunlight.Plants and other oxygenic phototrophs have developed a suite of photoprotective mechanisms to prevent photoinhibition and oxidative stress caused by excess or fluctuating light conditions.
UVA rays are able to penetrate deeper into the skin than UVB rays, damaging the dermal layer as well as the epidermal. The dermis is the second major layer of the skin and it comprises collagen, elastin, and extrafibrillar matrix which provides structural support to the skin. However, with constant UVA exposure, the size of the dermis layer ...