Sun tanning



Sun tanning or simply tanning is the process whereby skin color is darkened or tanned. The process is most often a result of exposure to ultraviolet (UV) radiation from the sun or from artificial sources, such as a tanning bed, but can also be a result of windburn or reflected light. Many people deliberately tan their skin by exposure to the sun, called sun bathing, or by the use of artificial tanning methods. Some people use chemical products which can produce a tanning result without exposure to ultraviolet radiation. Casual exposure to the sun has moderate beneficial impact, including the production of vitamin D by the body; but excessive exposure to ultraviolet rays has detrimental health effects, including possible sunburn and even skin cancer as well as depressed immune system function and increased risk of accelerated aging. To avoid sunburn, most people apply suitable sunscreen to skin exposed to the sun, but others use oils to accelerate the tanning process. Tanning is the skin cell's way of indicating that it has been damaged. Over time, cumulative exposure can result in increased risk for skin cancer and skin damage.

Some people tan or sunburn more easily than others. This may be the result of different skin types and natural skin color, and these may be as a result of genetics.

The term "tanning" has a cultural origin, arising from the color tan. Its origin lays in the Western culture of Europe when it became fashionable for young white ladies to seek a less pale complexion (see Cultural history below).

The tanning process
Melanin is produced by cells called melanocytes in a process called melanogenesis. Melanocytes produce two types of melanin: pheomelanin (red) and eumelanin (very dark brown). Melanin protects the body by absorbing solar radiation. Excessive solar radiation causes direct and indirect DNA damage to the skin and the body naturally combats and seeks to repair the damage and protect the skin by creating and releasing further melanin into the skin's cells. With the production of the melanin, the skin color darkens, but can also cause sunburn. The tanning process can also be created by artificial UV radiation.

There are two different mechanisms involved. Firstly, the UVA-radiation creates oxidative stress, which in turn oxidises existing melanin and leads to rapid darkening of the melanin. Secondly, there is an increase in production of melanin (melanogenesis), which is the body's reaction to photodamage from UV radiation. Melanogenesis leads to delayed tanning and first becomes visible about 72 hours after exposure. The tan that is created by an increased melanogenesis lasts much longer than the one that is caused by oxidation of existing melanin.

The ultraviolet frequencies responsible for tanning are often divided into the UVA and UVB ranges:

UVA
Ultraviolet A (UVA) radiation is in the wavelength range 320 to 400 nm. It is present more uniformly throughout the day, and throughout the year, than UVB. UVA causes the release of existing melanin from the melanocytes to combine with oxygen (oxidize) to create the actual tan color in the skin. It is blocked less than UVB by many sunscreens but is blocked to some degree by clothing.

UVB
Ultraviolet B (UVB) radiation is in the wavelength range 280 to 320 nm. UVB:


 * triggers the formation of CPD-DNA damage (direct DNA damage) which in turn induces an increased melanin production
 * is more likely to cause a sunburn than UVA as a result of overexposure. The mechanism for sunburn and increased melanogenesis is identical. Both are caused by the direct DNA damage (formation of CPDs)
 * produces Vitamin D in human skin
 * reduced by virtually all sunscreens in accordance with their SPF
 * is thought, but not proven, to cause the formation of moles and some types of skin cancer
 * causes skin aging (but at a far slower rate than UVA.)
 * stimulates the production of new melanin, which leads to a big increase in the dark-coloured pigment within a few days.

Tanning behaviour of different skin colors
A person's natural skin color has an impact on their reaction to exposure to the sun. An individual's natural skin color can vary from a dark brown to a nearly colorless pigmentation, which may appear reddish due to the blood in the skin. Though subject to variations, ethnic Europeans generally have lighter skin, while ethnic Africans generally have darker skin. In 1975, Harvard dermatologist Thomas B. Fitzpatrick devised the Fitzpatrick scale which described the common tanning behaviour of various skin types, as follows:

Avoiding tan lines
The wearing of clothing while tanning results in creation of tan lines, which many people regard as un-aesthetic and embarrassing. Many people desire to avoid creation of tan lines on those parts of the body which will be visible when they are fully clothed. Some people try to achieve an all-over tan or to maximize their tan coverage. To achieve an all-over tan, the tanner needs to dispense with clothing; and to maximize covering, they need to minimize the amount of clothing they wear while tanning. For those women who cannot dispense with a swimsuit, they at times tan with the back strap undone while lying on the front, or removing shoulder straps, besides wearing swimsuits which cover less area than their normal clothing. Any exposure is subject to local community standards and personal choice. Some people tan in the privacy of their backyard where they can at times tan without clothes, and some countries have set aside clothing-optional swimming areas (also known as nude beaches), where people can tan and swim clothes-free. Some people tan topless, and others wear very brief swimwear, such as a microkini. A recent innovation is tan-through swimwear, which uses fabric which is perforated with thousands of micro holes that are nearly invisible to the naked eye, but which let enough sunlight through to produce a line-free tan. Tan-through swimsuits offer SPF protection of about 6, and an application of full-strength sunscreen even to the covered area is recommended.

Because of the potential sunburn which can result from excessive exposure to direct sunlight, many people suntan in moderation and wear some clothing, including a hat, and use suitable sunscreen. From time to time they also sit in the shade or cool off in water.

Sunless tanning
To avoid exposure to UVB and UVA rays, or in sunless seasons, some people darken their skin using sunless tanning (also known as self-tanners). A number of types of sunless tanning options are available, including stainers which are based on dihydroxyacetone (DHA); bronzers, which basically are dyes; tan accelerators, based on tyrosine and psolarens. Some people use make-up to create a tanned appearance. Another option is to tan using a tanning bed or sunlamp. The use of a tanning bed exposes the user to similar UV radiation as that of the sun.

Many sunless tanning products are available in the form of creams, gels, lotions, and sprays that are self-applied on the skin. Another option is the use of bronzers which are cosmetics that provide temporary effects. There is also a professional spray-on tanning option or “tanning booths” that is offered by spas, salons, and tanning businesses.

Spray tanning does not mean that a color is sprayed on the body. What is used in the spray tanning process is a colorless chemical which burns the dead cells located on the top layer of the skin, resulting in a brown color. The two main active ingredients used in most of the sunless tanners are dihydroxyacetone and erythrulose.

The U.S. Food and Drug Administration (FDA) has not approved the use of DHA spray tanning booths because it has not received safety data to support this specific use. DHA is a permitted color additive for cosmetic use restricted to external application. When used in a commercial spray tanning booth, areas such as the eyes, lips or mucous membrane are exposed to the DHA which is a non permitted use of the product.

Tanning controversy
Overexposure to ultraviolet radiation is known to cause skin cancer, make skin age and wrinkle faster, mutate DNA, and reduce the immune system. Frequent tanning bed use triples the risk of developing melanoma, the deadliest form of skin cancer. The US Public Health Service states that UV radiation, including the use of sun lamps and sun beds are "known to be a human carcinogen." It further states that the risk of developing cancer in the years after exposure is greatest in people under 30 years old. However, recently released FDA data suggests that indoor tanning beds emit 12x more UVA radiation than the sun and has been categorized in the "highest cancer risk" group along with smoking tobacco.

Some researchers have advised that tanning in moderation may be healthier than is commonly believed. Edward Giovannucci, professor of medicine and nutrition at Harvard, states that according to his research, people who have sufficient vitamin D due to UV exposure, and other intake, may prevent 30 deaths for each one caused by skin cancer. His research also suggests that diet accounts very little for vitamin D3 necessary for curbing cancer. Michael Holick, former Boston professor of dermatology, claimed that moderate exposure to sunlight probably reduces risk to many forms of cancer, diabetes, seasonal affective disorder, and other diseases. These researchers are vigorously opposed by most dermatologists, for example, Dr. Elewski, president of the American Academy of Dermatology, argued that minutes of exposure to sunlight can be dangerous, and that people can get all the vitamin D they need through supplements. Large clinical studies have found vitamin D produced both through exposure to sunlight and through dietary supplements dramatically decreases cancer risk, and helps cancer recovery. See Vitamin D for more details.

In his book Physician's guide to sunscreens Nicholas J. Lowe pointed out that one of the reasons why people reject sunscreen use is the reduction of tanning that is associated with good sunscreen protection. He then reports about several tanning activators. The specific substances which he writes about are different forms of psoralen. These substances were known to be photocarcinogenic since 1979,  but health authorities banned psoralen only in July 1996.

Cultural history


Throughout history, tanning has gone in and out of fashion. In Western countries before about the 1920s, a tanned skin was associated with lower class, being associated with outdoor work.

Women even went as far as to put lead-based cosmetics on their skin to artificially whiten their skin tone. However, when not strictly monitored these cosmetics caused lead poisoning. Achieving a light-skinned appearance was brought about in many other ways, including the use of arsenic to whiten skin, and powders. Other methods included wearing of full length clothes when outdoors, including gloves and parasols. The preference for fair-skin continued until the end of the Victorian era.

In 1903, Niels Finsen was awarded the Nobel Prize in medicine for his “Finsen Light Therapy”. The therapy was a cure for infectious diseases such as lupus vulgaris and rickets. Vitamin D deficiency was found to be a cause of rickets disease, and exposure to the sun would allow vitamin D to be produced in a person. Therefore, sun exposure was a remedy to curing several diseases, especially rickets.

Shortly thereafter, in the 1920s, Coco Chanel accidentally got sunburnt while visiting the French Riviera. Her fans apparently liked the look and started to adopt darker skin tones themselves. Tanned skin became a trend partly because of Coco’s status and the longing for her lifestyle by other members of society. In addition, Parisians fell in love with Josephine Baker, a “caramel-skinned” singer in Paris. Those who liked and idolized her wanted darker skin so they could be more like her. These two French women were two trendsetters of the transformation of tanned skin being viewed as fashionable, healthy, and luxurious, but not by the whole population.

In the 1940s, advertisements started appearing in women’s magazines which encouraged sun bathing. At this time, swimsuits' skin coverage began decreasing, with the bikini making its appearance in 1946. In the 1950s, many people used baby oil as a method to tan more quickly. The first self-tanner came about in the same decade and was known as “Man-Tan,” and often led to undesirable orange skin. Coppertone, in 1953, brought out the little blond girl and her cocker spaniel tugging on her bathing suit bottoms on the cover of their sunscreen bottles; this is still the same advertisement they use today on their bottles of sunscreen. In the latter part of the 1950s, silver metallic UV reflectors were common to enhance one’s tan.

In 1962, sunscreen commenced to be SPF rated, although in the US SPF labeling was not standardized by the FDA until 1978. In 1971, Mattel introduced Malibu Barbie, which had tanned skin, sunglasses, and her very own bottle of sun tanning lotion. In 1978, tanning beds appeared. Today there are an estimated 50,000 outlets for tanning, whereas in the 1990s there were only around 10,000. The tanning business is a five-billion dollar industry. Also in 1978, sunscreen with a SPF 15 first appeared.