|
Oils, Creams
Sun tanning describes a darkening of the skin (especially of fair-skinned individuals) in a natural physiological response stimulated by exposure to ultraviolet radiation from sunshine or from artificial sources such as a tanning bed. more...
 Home
Bath & Body
Coupons
Dietary Supplements,...
Hair Care
Hair Removal
Health Care
Massage
 Chairs
Massage Pillows
Massage Stones, Rocks
Massagers
Oils, Creams
Other Massage Products
Tables
Medical, Special Needs
Nail
Natural Therapies
Oral Care
Other Health & Beauty Items
Over-the-Counter Medicine
Skin Care
Tanning Beds, Lamps
Tattoos, Body Art
Vision Care
Weight Management
Wholesale Lots
With excess exposure to ultraviolet, a sunburn can develop.
Cause and effect
Darkening of the skin is caused by an increased release of the pigment melanin into the skin's cells after exposure to ultraviolet radiation. Melanin is produced by cells called melanocytes and protects the body from absorbing an excess of solar radiation, which can be harmful. Depending on genetics, some people can darken quickly and deeply whereas others do not darken much at all.
The ultraviolet frequencies responsible for tanning are often divided into the UVA (315 to 400nm wavelength) and UVB (280 to 315nm wavelength) ranges. UVB waves have higher energy than UVA waves and are therefore more damaging and more carcinogenic.
UVB
triggers creation and secretion of new melanin into the skin;
is thought to cause the formation of moles and some types of skin cancer (but not melanoma);
causes skin aging (but at a far slower rate than UVA.);
produces Vitamin D in human skin;
is more likely to cause a sunburn than UVA as a result of overexposure;
reduced by virtually all sunscreens in accordance with their SPF;
UVA
causes release of preexisting melanin from the melanocytes;
causes the melanin to combine with oxygen (oxidize), which creates the actual tan color in the skin;
seems to cause cancer less than UVB, but causes melanoma, a far more dangerous type of skin cancer than other types;
is blocked less than UVB by many sunscreens but is blocked to some degree by clothing;
is present more uniformly throughout the day, and throughout the seasons than UVB;
Health benefits
The skin produces vitamin D in response to sun exposure (in particular, UVB waves in the 285nm to 287nm range), which can be a health benefit for those with vitamin D deficiency. In 2002, Dr. William B. Grant published an article claiming that 23,800 premature deaths occur in the US annually from cancer due to insufficient UVB exposures (apparently via vitamin D deficiency). This is higher than 8,800 deaths occurred from melanoma or squamous cell carcinoma, so the overall effect of sun tanning might be beneficial. Another research estimates that 50,000–63,000 individuals in the United States and 19,000 - 25,000 in the UK die prematurely from cancer annually due to insufficient vitamin D.
Read more at Wikipedia.org
|
|
