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Sun tanning or tanning is the process whereby skin color is darkened or tanned. It is most often a result of exposure to ultraviolet (UV) radiation from
sunlight Sunlight is a portion of the electromagnetic radiation given off by the Sun, in particular infrared, visible, and ultraviolet light. On Earth, sunlight is scattered and filtered through Earth's atmosphere, and is obvious as daylight when ...
or from artificial sources, such as a tanning lamp found in indoor tanning beds. People who deliberately tan their skin by exposure to the sun engage in a passive recreational activity of sun bathing. Some people use chemical products which can produce a tanning effect without exposure to ultraviolet radiation, known as sunless tanning.


Impact on skin health

Moderate exposure to direct sunlight contributes to the production of
melanin Melanin (; from el, μέλας, melas, black, dark) is a broad term for a group of natural pigments found in most organisms. Eumelanin is produced through a multistage chemical process known as melanogenesis, where the oxidation of the amino ...
and
vitamin D Vitamin D is a group of Lipophilicity, fat-soluble secosteroids responsible for increasing intestinal absorption of calcium, magnesium, and phosphate, and many other biological effects. In humans, the most important compounds in this group ar ...
by the body, but excessive exposure to ultraviolet rays has negative health effects, including
sunburn Sunburn is a form of radiation burn that affects living tissue, such as skin, that results from an overexposure to ultraviolet (UV) radiation, usually from the Sun. Common symptoms in humans and animals include: red or reddish skin that is h ...
and increased risk of
skin cancer Skin cancers are cancers that arise from the skin. They are due to the development of abnormal cells that have the ability to invade or spread to other parts of the body. There are three main types of skin cancers: basal-cell skin cancer (BCC) ...
, as well as depressed immune system function and accelerated aging of the skin. 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 a result of
genetics Genetics is the study of genes, genetic variation, and heredity in organisms.Hartl D, Jones E (2005) It is an important branch in biology because heredity is vital to organisms' evolution. Gregor Mendel, a Moravian Augustinian friar work ...
. The term "tanning" has a cultural origin, arising from the color tan. Its origin lies in the Western culture of
Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...
when it became fashionable for young
women A woman is an adult female human. Prior to adulthood, a female human is referred to as a girl (a female child or Adolescence, adolescent). The plural ''women'' is sometimes used in certain phrases such as "women's rights" to denote female hum ...
to seek a less pale complexion (see
Cultural history Cultural history combines the approaches of anthropology and history to examine popular cultural traditions and cultural interpretations of historical experience. It examines the records and narrative descriptions of past matter, encompassing t ...
below).


Tanning process

Melanin Melanin (; from el, μέλας, melas, black, dark) is a broad term for a group of natural pigments found in most organisms. Eumelanin is produced through a multistage chemical process known as melanogenesis, where the oxidation of the amino ...
is a natural pigment produced by cells called
melanocyte Melanocytes are melanin-producing neural crest-derived cells located in the bottom layer (the stratum basale) of the skin's epidermis, the middle layer of the eye (the uvea), the inner ear, vaginal epithelium, meninges, bones, and hear ...
s in a process called
melanogenesis Melanocytes are melanin-producing neural crest-derived cells located in the bottom layer (the stratum basale) of the skin's epidermis, the middle layer of the eye (the uvea), the inner ear, vaginal epithelium, meninges, bones, and hear ...
. Melanocytes produce two types of melanin:
pheomelanin Melanin (; from el, μέλας, melas, black, dark) is a broad term for a group of natural pigments found in most organisms. Eumelanin is produced through a multistage chemical process known as melanogenesis, where the oxidation of the am ...
(red) and
eumelanin Melanin (; from el, μέλας, melas, black, dark) is a broad term for a group of natural pigments found in most organisms. Eumelanin is produced through a multistage chemical process known as melanogenesis, where the oxidation of the am ...
(very dark brown). Melanin protects the body by absorbing ultraviolet radiation. Excessive UV radiation causes sunburn along with other
direct Direct may refer to: Mathematics * Directed set, in order theory * Direct limit of (pre), sheaves * Direct sum of modules, a construction in abstract algebra which combines several vector spaces Computing * Direct access (disambiguation), ...
and
indirect DNA damage Indirect, the opposite of direct, may refer to: * Indirect approach, a battle strategy * Indirect DNA damage, caused by UV-photons *Indirect agonist or indirect-acting agonist, a substance that enhances the release or action of an endogenous neurot ...
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. The tanning process can be triggered by natural sunlight or by artificial UV radiation, which can be delivered in frequencies of UVA, UVB, or a combination of both. The intensity is commonly measured by the
UV Index The ultraviolet index, or UV index, is an international standard measurement of the strength of the sunburn-producing ultraviolet (UV) radiation at a particular place and time. It is primarily used in daily and hourly forecasts aimed at the general ...
. There are two different mechanisms involved in the production of a tan by UV exposure: Firstly, UVA radiation creates oxidative stress, which in turn oxidizes existing melanin and leads to rapid darkening of the melanin. UVA may also cause melanin to be redistributed (released from melanocytes where it is already stored), but its total quantity is unchanged. Skin darkening from UVA exposure does not lead to significantly increased production of melanin or protection against sunburn. In the second process, triggered primarily by UVB, there is an increase in production of melanin (melanogenesis), which is the body's reaction to direct DNA photodamage (formation of
pyrimidine dimer Pyrimidine dimers are molecular lesions formed from thymine or cytosine bases in DNA via photochemical reactions, commonly associated with direct DNA damage. Ultraviolet light (UV; particularly UVB) induces the formation of covalent linkages betw ...
s) from UV radiation. Melanogenesis leads to delayed tanning, and typically becomes visible two or three days after exposure. The tan that is created by increased melanogenesis typically lasts for a few weeks or months, much longer than the tan that is caused by oxidation of existing melanin, and is also actually protective against UV skin damage and sunburn, rather than simply cosmetic. Typically, it can provide a modest
Sun Protection Factor Sunscreen, also known as sunblock or sun cream, is a photoprotective topical product for the skin that mainly absorbs, or to a much lesser extent reflects, some of the sun's ultraviolet (UV) radiation and thus helps protect against sunburn ...
(SPF) of 3, meaning that tanned skin would tolerate up to 3 times the UV exposure as pale skin. However, in order to cause true melanogenesis-tanning by means of UV exposure, some direct DNA photodamage must first be produced, and this requires UVB exposure (as present in natural sunlight, or sunlamps that produce UVB). The
ultraviolet Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30  PHz) to 400 nm (750  THz), shorter than that of visible light, but longer than X-rays. UV radiation ...
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. Most UVA is not blocked by the atmosphere's
ozone layer The ozone layer or ozone shield is a region of Earth's stratosphere that absorbs most of the Sun's ultraviolet radiation. It contains a high concentration of ozone (O3) in relation to other parts of the atmosphere, although still small in rel ...
. UVA causes the release of existing melanin from the melanocytes to combine with oxygen (oxidize) to create the actual tan color in the skin. UVA is blocked less than UVB by many sunscreens, but is blocked to some degree by clothing. UVA is known both to cause DNA damage and to be carcinogenic. However, it operates not by inducing direct DNA damage, but by producing reactive oxygen species which damage DNA indirectly. UVA (see above) induces a cosmetic tan but little extra melanin protection against sun damage, sun burn, or cancer.


UVB

Ultraviolet B (UVB) radiation is in the wavelength range 280 to 320 nm. Much of this band is blocked by the Earth's ozone layer, but some penetrates. UVB: * triggers the formation of CPD-DNA damage ( direct DNA damage), which in turn induces an increased
melanin Melanin (; from el, μέλας, melas, black, dark) is a broad term for a group of natural pigments found in most organisms. Eumelanin is produced through a multistage chemical process known as melanogenesis, where the oxidation of the amino ...
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 Vitamin D is a group of Lipophilicity, fat-soluble secosteroids responsible for increasing intestinal absorption of calcium, magnesium, and phosphate, and many other biological effects. In humans, the most important compounds in this group ar ...
in human skin. * is reduced by virtually all sunscreens in accordance with their SPF. * is thought, but not proven, to cause the formation of
moles Moles can refer to: * Moles de Xert, a mountain range in the Baix Maestrat comarca, Valencian Community, Spain *The Moles (Australian band) *The Moles, alter ego of Scottish band Simon Dupree and the Big Sound People * Abraham Moles, French engin ...
and some types of skin cancer. * causes skin aging (but at a slower rate than UVA). * stimulates the production of new melanin, which leads to an increase in the dark-colored pigment within a few days.


Tanning behavior of different skin colors

A person's natural skin color affects their reaction to exposure to sunlight. An individual's natural skin color can vary from a dark brown to a nearly colorless pigmentation, which may appear white. In 1975, Harvard dermatologist
Thomas B. Fitzpatrick Thomas B. Fitzpatrick (December 19, 1919 – November 16, 2003) was an American dermatologist. He was Chairman of the Department of Dermatology at Harvard Medical School and Chief of the Massachusetts General Hospital Dermatology Service from 195 ...
devised the Fitzpatrick scale which described the common tanning behavior of various skin types, as follows:


Health aspects

The most common risk of exposure to ultraviolet radiation is
sunburn Sunburn is a form of radiation burn that affects living tissue, such as skin, that results from an overexposure to ultraviolet (UV) radiation, usually from the Sun. Common symptoms in humans and animals include: red or reddish skin that is h ...
, the speed and severity of which vary among individuals. This can be alleviated at least to some extent by the prior application of a suitable-strength
sunscreen Sunscreen, also known as sunblock or sun cream, is a photoprotective topical product for the skin that mainly absorbs, or to a much lesser extent reflects, some of the sun's ultraviolet (UV) radiation and thus helps protect against sunbur ...
, which will also hinder the tanning process due to the blocking of UV light. Overexposure to ultraviolet radiation is known to cause
skin cancer Skin cancers are cancers that arise from the skin. They are due to the development of abnormal cells that have the ability to invade or spread to other parts of the body. There are three main types of skin cancers: basal-cell skin cancer (BCC) ...
, make skin age and wrinkle faster, mutate DNA, and impair the immune system. Frequent tanning bed use triples the risk of developing
melanoma Melanoma, also redundantly known as malignant melanoma, is a type of skin cancer that develops from the pigment-producing cells known as melanocytes. Melanomas typically occur in the skin, but may rarely occur in the mouth, intestines, or eye ( ...
, the deadliest form of skin cancer, according to a 2010 study. The study suggests that the melanoma risk is linked more closely to total exposure than it is to the age at which an individual first uses a tanning bed.Peeples, Lynne
Study: Frequent tanning-bed use triples melanoma risk.
CNN, 27 May 2010.
The
International Agency for Research on Cancer The International Agency for Research on Cancer (IARC; french: Centre International de Recherche sur le Cancer, CIRC) is an intergovernmental agency forming part of the World Health Organization of the United Nations. Its role is to conduct and ...
places the use of tanning beds in the highest cancer risk category, describing them as carcinogenic to humans even if used as recommended. Frequent tanning also has behavioural reinforcing effects, following UVA radiation epidermal keratinocytes synthesize POMC inducing the production of β-Endorphins which are opioid agonists. An opioid blockade will also then cause withdrawal signs after habitual UV exposure leading to many tanners meeting the DSM-IV criteria for addiction. Several organizations, such as the World Health Organization (WHO), the
American Cancer Society The American Cancer Society (ACS) is a nationwide voluntary health organization dedicated to eliminating cancer. Established in 1913, the society is organized into six geographical regions of both medical and lay volunteers operating in more than ...
and the US Surgeon General have issued guidelines warning about sun tanning and UV radiation exposure, either from the sun or from indoor tanning. Production of vitamin D is essential for human health. Moderate exposure (avoiding sunburn) to UV radiation provides benefits such as increased vitamin D, as well as other possible benefits that are still being studied. Several tanning activators have used different forms of
psoralen Psoralen (also called psoralene) is the parent compound in a family of naturally occurring organic compounds known as the linear furanocoumarins. It is structurally related to coumarin by the addition of a fused furan ring, and may be considered ...
, which are known to be photocarcinogenic. Health authorities have banned psoralen since July 1996.


Cultural history

Tanning has gone in and out of fashion over the course of history. In the United States and Western Europe before the 1920s, tanned skin was associated with the lower classes because they worked outdoors and were exposed to the sunlight. Women in particular went to great lengths to preserve pale skin, as a sign of their "refinement". Women's outdoor clothing styles were tailored to protect them against sunlight exposure, with full-length sleeves, and sunbonnets and other large hats, headscarves, and parasols shielding the head. Lead- and
arsenic Arsenic is a chemical element with the symbol As and atomic number 33. Arsenic occurs in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal. Arsenic is a metalloid. It has various allotropes, b ...
-based cosmetics were used to artificially whiten the skin. The preference for fair skin continued until the end of the
Victorian era In the history of the United Kingdom and the British Empire, the Victorian era was the period of Queen Victoria's reign, from 20 June 1837 until her death on 22 January 1901. The era followed the Georgian period and preceded the Edwa ...
. By the early 20th century, the therapeutic benefits of sunlight began to be recognized. In 1903, Niels Finsen was awarded the Nobel Prize in Medicine for his “Finsen Light Therapy”. The therapy was a cure for diseases such as lupus vulgaris and
rickets Rickets is a condition that results in weak or soft bones in children, and is caused by either dietary deficiency or genetic causes. Symptoms include bowed legs, stunted growth, bone pain, large forehead, and trouble sleeping. Complications ma ...
. Vitamin D deficiency was found to be a cause of rickets, and exposure to sunlight would allow vitamin D to be produced in a person. Therefore, sunlight exposure was a remedy to curing several diseases, especially rickets. In 1910 a scientific expedition went to the island of
Tenerife Tenerife (; ; formerly spelled ''Teneriffe'') is the largest and most populous island of the Canary Islands. It is home to 43% of the total population of the Archipelago, archipelago. With a land area of and a population of 978,100 inhabitant ...
to test the wider health benefits of "heliotherapy", and by 1913 "sunbathing" was referred to as a desirable activity for the leisured class. Shortly thereafter, in the 1920s, fashion-designer
Coco Chanel Gabrielle Bonheur "Coco" Chanel ( , ; 19 August 1883 – 10 January 1971) was a French fashion designer and businesswoman. The founder and namesake of the Chanel brand, she was credited in the post-World War I era with popularizing a sporty, c ...
accidentally got sunburnt while visiting the
French Riviera The French Riviera (known in French as the ; oc, Còsta d'Azur ; literal translation " Azure Coast") is the Mediterranean coastline of the southeast corner of France. There is no official boundary, but it is usually considered to extend from ...
. When she arrived home, she arrived with a sun tan and 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 Josephine Baker (born Freda Josephine McDonald; naturalised French Joséphine Baker; 3 June 1906 – 12 April 1975) was an American-born French dancer, singer and actress. Her career was centered primarily in Europe, mostly in her adopted Fran ...
, a "caramel-skinned" singer in
Paris Paris () is the capital and most populous city of France, with an estimated population of 2,165,423 residents in 2019 in an area of more than 105 km² (41 sq mi), making it the 30th most densely populated city in the world in 2020. Si ...
, and idolized her dark skin. These two women were leading figures of the transformation that tanned skin underwent, in which it became perceived as fashionable, healthy, and luxurious.
Jean Patou Jean Patou (; 27 September 1887 – 8 March 1936) was a French fashion designer, and founder of the Jean Patou brand. Early life Patou was born in Paris, France in 1887. Patou's family's business was tanning and furs. Patou worked with his ...
capitalized on the new tanning fad, launching the first sun tan oil "Huile de Chaldee" in 1927. Just before the 1930s, sunlight therapy became a popularly subscribed cure for almost every ailment from simple fatigue to tuberculosis. In the 1940s, advertisements started appearing in women's magazines which encouraged sunbathing. At the same time,
swimsuit A swimsuit is an item of clothing designed to be worn by people engaging in a water-based activity or water sports, such as swimming, diving and surfing, or sun-orientated activities, such as sun bathing. Different types may be worn by men, ...
s' skin coverage began decreasing, with the bikini radically changing swimsuit style after it made its appearance in 1946. In the 1950s, many people used
baby oil Baby oil is, in general terms, an inert oil for the purpose of keeping skin soft and supple. It is often used on babies for the purpose of maintaining "baby-soft" skin, but it is also often used by adults for skincare and massage. The skin of an ...
as a method to increase tanning. The first self-tanner came about in the same decade and was known as "Man-Tan", although it often led to undesirable orange skin.
Coppertone Coppertone is the brand name for an American sunscreen. Coppertone is headquartered in Whippany, New Jersey. Coppertone uses a variety of branding, including the Coppertone girl logo and a distinctive fragrance. Product line The original prod ...
, in 1953, marketed its sunscreen with a drawing of a little blond girl and her cocker spaniel tugging on her bathing suit bottom, revealing her bare bottom and tan line; this advertisement was modified around the turn of the 21st century and now shows a little girl wearing a one-piece bathing suit or shorts. In the latter part of the 1950s, silver metallic reflectors were common to enhance one’s tan. In 1962, sunscreen commenced to be SPF rated, although SPF labeling in the US was not standardized by the FDA until 1978. In 1971,
Mattel Mattel, Inc. ( ) is an American multinational toy manufacturing and entertainment company founded in January 1945 and headquartered in El Segundo, California. The company has presence in 35 countries and territories and sells products in mor ...
introduced Malibu Barbie, which had tanned skin,
sunglasses Sunglasses or sun glasses (informally called shades or sunnies; more names Sunglasses#Other names, below) are a form of Eye protection, protective eyewear designed primarily to prevent bright sunlight and high-energy visible light from damagin ...
, and her very own bottle of sun tanning lotion. In 1978, both sunscreen with an SPF 15 rating as well as tanning beds first appeared. In 2007, there were an estimated 50,000 outlets for indoor tanning; it was a five-billion-dollar industry in the United States, and had spawned an auxiliary industry for indoor tanning lotions including bronzers, intensifiers, and accelerators. Since then, the indoor tanning industry has become more constrained by health regulations. In China, darker skin is still considered by many to be the mark of the lower classes. As recently as 2012, in some parts of China,
ski mask A balaclava, also known as a balaclava helmet or ski mask, is a form of cloth headgear designed to expose only part of the face, usually the eyes and mouth. Depending on style and how it is worn, only the eyes, mouth and nose, or just the fron ...
s were becoming popular items to wear at the beach in order to protect the wearer's face from the effects of sunlight. A 1969 innovation is tan-through swimwear, which uses fabric perforated with thousands of micro holes that are nearly invisible to the naked eye, but which transmit enough sunlight to approach an all-over tan, especially if the fabric is stretched taut. Tan-through swimwear typically allows more than one-third of UV rays to pass through (equivalent to SPF 3 or less), and an application of sunscreen even to the covered area is recommended.


Sunless tanning

To avoid exposure to UVB and UVA rays, or in seasons without strong sunshine, some people take alternative steps to appear with darkened skin. They may use sunless tanning (also known as self-tanners); stainers which are based on dihydroxyacetone (DHA); or
cosmetics Cosmetics are constituted mixtures of chemical compounds derived from either natural sources, or synthetically created ones. Cosmetics have various purposes. Those designed for personal care and skin care can be used to cleanse or protec ...
such as bronzers. Many sunless tanning products are available in the form of darkening creams, gels, lotions, and sprays that are self-applied on the skin. There is also a professional spray-on tanning option or “
tanning booth Indoor tanning involves using a device that emits ultraviolet radiation to produce a cosmetic tan. Typically found in tanning salons, gyms, spas, hotels, and sporting facilities, and less often in private residences, the most common device is a h ...
” that is offered by spas, salons, and tanning businesses. Spray tanning does not involve a color being sprayed on the body, instead it uses a colorless chemical which reacts with proteins in the top layer of the skin, resulting in a brown color.


See also

*
Sunburn Sunburn is a form of radiation burn that affects living tissue, such as skin, that results from an overexposure to ultraviolet (UV) radiation, usually from the Sun. Common symptoms in humans and animals include: red or reddish skin that is h ...
* Indoor tanning * Perineum sunning * Skin whitening


References


External links


Aim at MelanomaInformation on tanning from The Skin Cancer FoundationResearch on the benefits of UV exposureMelanoma Research Alliance
{{DEFAULTSORT:Sun Tanning Sun tanning