Sun tanning

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 a sunbed).

Cause and effect

Darkening of the skin is caused by an increase or 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.

There are two frequencies of light that cause tanning: UVA and UVB.

UVB

triggers creation and secretion of new melanin into the skin

significantly distorts and damages DNA strands

causes the formation of moles and some types of skin cancer (but not melanoma)

causes skin aging (but at a far slower rate than UVA.)

stimulates the production of Vitamin D, which promotes lower rates of disease, and ironically lower rates of skin and other types of cancer

is more likely to cause a sunburn than UVA as a result of overexposure, however moderate exposure can be healthy

is almost completely blocked by virtually all sunscreens

UVA

causes release of preexisting melanin from the melanocytes

causes much of skin aging

seems to cause cancer less than UVB, but causes melanoma, a far more dangerous type of skin cancer than other types

is not blocked by many sunscreens but is blocked to some degree by clothing

is present more uniformly throughout the day, and throughout the seasons than UVB

Cultural history

Culturally, a suntan may be regarded as attractive although this is susceptible to the whims of fashion. In ancient Rome, women deliberately lightened their skin with lead based cosmetics. At the time of Shakespeare, to be tanned signified lower status; in Much Ado About Nothing, Act II, Scene I, Beatrice observes of her self-perceived unnattractiveness and her consequent lack of marriage prospects:

Thus goes every one to the world but I, and I am sunburnt; I may sit in a corner and cry heigh-ho for a husband!

During much of the 18th and 19th centuries, fair, freckleless skin was considered attractive, especially in women, since tanned skin was associated with manual labour such as on a farm or in the outdoor employ of a wealthier person. Having fair skin signified that one was wealthy enough to hire other people to do manual labour. In 18th Century France, members of the royal court emphasised this point by powdering their faces to look as white as possible. As labour patterns shifted during the early 20th century, with indoor work becoming the norm, tanned skin came to be seen as a credential for membership of the leisured classes; when famous fashion designer Coco Chanel accidentally acquired a dark tan during a vacation on the French Riviera in the 1920's, she ignited a fad for tanned skin. By the 1960s a tan's earlier social significance had been reversed and bronzed skin often signified social status, wealth and good health, possibly for the opposite reason - now that most jobs are done inside, tans signify the wealth required to have the leisure time to get one.

In 1985 however, the American Academy of Dermatology (AAD) launched a public education program warning about the risks of overexposure to the sun and in 1988, modeling agency director Eileen Ford said, "The tanned look is dead". By 1990, 600,000 new cases of skin cancer had been diagnosed and 27,600 of these involved malignant melanoma. That year there were 8,800 deaths from melanoma or squamous cell carcinoma and the incidence of these skin diseases continued to rise. Although these risks were widely publicised, in a 1997 Seventeen magazine survey, two thirds of teens responding said they "look better with a tan and feel healthier, more sophisticated," and half said they looked "more athletic."

Health risks

Sunburns are a symptom of skin damage and are associated with skin cancer. Overexposure to the sun has been linked to melanoma. Too much sun can also lead to eye problems if UV Protected sun-glasses aren't worn, along with damage to the immune system.

Concerns about skin damage due to UV exposure have resulted in the development of products which give the appearance of a suntan without exposure to the sun (see sunless tanning).

A study by Dr. Anthony Liguori and others, published in the July 2004 issue of the Journal of the American Academy of Dermatology, Part 1, suggests that indoor sun tanning may be addictive. Ultraviolet light stimulates the production of endorphins (through the production of Vitamin D), resulting in a natural sensation of well-being.

Health benefits

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 much higher than 8,800 deaths occurred from melanoma or squamous cell carcinoma, so the overall effect of sun tanning might be beneficial. Another effect of vitamin D deficiency is osteomalacia, which can result in bone pain, difficulty in weight bearing and sometimes fractures.

Ultraviolet radiation has other medical applications, in the treatment of skin conditions such as psoriasis and vitiligo.

Prevention

To avoid sunburn, one should use sunscreen, tanning oil or various over-the-counter creams. The SPF (Sun Protection Factor) number on a sunscreen product shows its rated effectiveness. Products with a higher SPF number are those designed to provide more defense for the skin against the effects of solar radiation. However in 1998, the Annual Meeting of the American Association for the Advancement of Science reported that some sunscreens advertising UVA and UVB protection do not provide adequate safety from UVA radiation and could give sun tanners a false sense of protection.

Tanning oils or creams, when applied, are usually thicker on some parts of skin than on others. This causes some parts of skin to get more UVA and UVB than others and thus get sunburns. For this reason, tanning oils or creams may increase the occurrence of skin cancer and other skin diseases.

For those who choose to tan, some dermatologists recommend the following preventative measures:

Make sure the sunscreen blocks both UVA and UVB rays. These types of sunscreens, called broad-spectrum sunscreens, contain more active ingredients. Ideally a sunscreen should also be hypoallergenic and noncomedogenic so it doesn't cause a rash or clog the pores, which can cause acne.
Sunscreen needs to be applied thickly enough to make a difference. People often do not put on enough sunscreen to get the full SPF protection. In case of uncertainty about how much product to use, or discomfort with the amount applied, switching to a sunscreen with a higher SPF may help.
Reapply sunscreen every 2 to 3 hours and after swimming or sweating. In direct sun, wear a sunscreen with a higher SPF (such as SPF 30). For playing sports the sunscreen should also be waterproof and sweatproof.
The rays of the sun are strongest between 10:00 AM and 4:00 PM, so frequent shade breaks are recommended during these hours. Sun rays are stronger at higher elevations (mountains) and lower latitudes (near the equator). One way to deal with time zones, daylight savings (summer time) and latitude is to check shadow length. If a person's shadow is shorter than their actual height, the risk of sunburn is much higher.
Wear a hat with a brim and anti-UV sunglasses which can provide almost 100% protection against ultraviolet radiation entering the eyes.
Be aware that reflective surfaces like snow and water can greatly increase the amount of UV radiation to which the skin is exposed.

The American Academy of Dermatology recommends the use of sunscreens, wearing protective clothing and avoiding the sun altogether.

Note: Not all experts agree with the Dermatology view that all sun exposure is bad, many believe that moderate sun exposure is healthy. Some discourage the use of sunscreen and recommend using hats and clothes to prevent overexposure.

External links

References

Grant, William B. (2002). An estimate of premature cancer mortality in the US due to inadequate doses of solar ultraviolet-B radiation. Cancer 94 (6), 1867–1875.
Matsumura Y, Ananthaswamy HN (2004). Toxic effects of UV radiation on the skin. Toxicol. Appl. Pharmacol. 195 (3), 298-308.
Hu S, et al. (2004). UV radiation and melanoma in US Hispanics & blacks. Arch Dermatol. 140 (7), 819-824.

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