Photo damage of skin, skin photoaging, negative effect of sunlight on skin phrases that often force us to hide from glance of Great Luminary. Going to the beach we abundantly cover our bodies with all types of sunscreens at once and stay under the sunshade the whole day. Doing all these we hardly know the protection from what exactly we are looking for.
From A (320-400 nm), B (290-320 nm) and C (10-290 nm) ultra violet components of the sunlight only A and B can reach the Earths surface and exactly they play the main role in a mechanism of sun action on skin.
The effect of sunlight on skin is multiple and depends on time of exposure, type of skin (most of all on degree of melanin pigmentation), and other bodys peculiarities including cancer susceptibility, state of immune and endocrine systems.
Few in number positive effects of sunlight not go beyond its ability help the body with vitamin D production and possibly repair of DNA.
Cumulative process of sun damage begins from thickening of epidermis to block ultra violet. The production of melanin pigment that absorbs the energy of UV light - increases and skin become obtain darker color (tan). Sunburn appears when the amount of UV exposure is greater than what can be protected against by skin melanin.
Penetrating into skin, ultra violet damages collagen major structure material in skin. Collagen breakdown causes accumulation of abnormal elastin that lead to formation of disorganized collagen fibers (solar scars) resulting in development of wrinkles.
Ultra violet radiation participates in creation of free radicals (oxidants) which are familiar by their ability to damage cell function and alter genetic material. After all free radicals activate metalloproteinase (chemical that break down collagen) that also is resulting in production of wrinkles.
Prevention of apoptosis (cell-suicide) is also ascribed to ultra violet numerous effects on skin. As a result damaged cells cant kill their selves and may become cancerous.
Chronic sun effects include photoaging (wrinkles, roughness and dryness, irregular pigmentation, small dilated blood vessels (telangiectasia), sallowness, and brown spots), actinic keratosis (scaly lesions) and skin cancer. Sunlight may also cause immune system changes by altering the distribution and function of white blood cells. Diffused opinion that sunscreens entirely protect from photoaging appeared to be wrong and as New England Journal of Medicine says even surprisingly small amounts of exposure to sunlight are enough to start the premature aging process.
For better protection cosmetologists advice to use retinoid creams (derivatives of vitamin A - tretinoin and tazarotene - have been approved by the FDA for improving the fine wrinkles and pigmentation of aging, and reducing roughness (tretinoin) or brown spots (tazarotene). Fluoracil creams are widely used for clearing actinic keratosis.
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