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 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 that can produce a tanning effect without exposure to ultraviolet radiation, known as sunless tanning.
Moderate exposure to direct sunlight contributes to the production of melanin and vitamin D by the body. [1]
Excessive exposure to ultraviolet rays has negative health effects, including sunburn. 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. [2] [3] The term "tanning" has a cultural origin, arising from the color tan. Its origin lies in the Western culture of Europe when it became fashionable for young women to seek a less pale complexion (see Cultural history below).
Excessive exposure may in the long-term increase the risk of skin cancer, [4] as well as depressed immune system function and accelerated aging of the skin. [5]
Melanin is a natural pigment produced by cells called melanocytes in a process called melanogenesis. [6] Melanocytes produce two types of melanin: pheomelanin (red) and eumelanin (very dark brown). Melanin protects the body by absorbing ultraviolet radiation. Excessive UV radiation causes sunburn along with other 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. 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. [7] The intensity is commonly measured by the UV Index. [8]
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. [9] In the second process, triggered primarily by UVB, there is an increase in production of melanin (melanogenesis), [10] which is the body's reaction to direct DNA photodamage (formation of pyrimidine dimers) from UV radiation. [11] Melanogenesis leads to delayed tanning, and typically becomes visible two or three days after exposure. [10] 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 (SPF) of 3, meaning that tanned skin would tolerate up to 3 times the UV exposure as pale skin. [12] 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).[ citation needed ] The ultraviolet frequencies responsible for tanning are often divided into the UVA and UVB ranges.
Ultraviolet A (UVA) radiation is in the wavelength range 320 to 400 nm. [13]
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:
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 devised the Fitzpatrick scale to describe the common tanning behavior of various skin types, as follows: [16] [17]
| Type | Also called | Sunburning | Tanning behavior | von Luschan scale |
|---|---|---|---|---|
| I | Very light or pale | Often | Occasionally | 1–5 |
| II | Light or light-skinned | Usually | Sometimes | 6–10 |
| III | Light intermediate | Rarely | Usually | 11–15 |
| IV | Dark intermediate | Rarely | Often | 16–21 |
| V | Dark or "brown" type | No | Sometimes darkens | 22–28 |
| VI | Very dark or "black" type | No | Naturally black-brown skin | 29–36 |
Dark skin does provide some protection against the sun’s ultraviolet rays, but it is a myth that people with dark skin tones are immune to the harmful effects of UV radiation. [18]
The most common risk of exposure to ultraviolet radiation is sunburn, 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, which also hinders the tanning process due to the blocking of UV light. Overexposure to ultraviolet radiation is known to cause skin cancer, [19] make skin age and wrinkle faster, [20] mutate DNA, [21] and impair the immune system. [22] Frequent tanning bed use triples the risk of developing melanoma, 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. [23] Frequent tanning also has behavioural reinforcing effects, [24] following UVA radiation epidermal keratinocytes synthesize POMC inducing the production of β-Endorphins, which are opioid agonists. An opioid blockade also then causes withdrawal signs after habitual UV exposure leading to many tanners meeting the DSM-IV criteria for addiction. [25] Several organizations, such as the World Health Organization (WHO), the American Cancer Society and the US Surgeon General have issued guidelines warning about sun tanning and UV radiation exposure, either from the sun or from indoor tanning. [26] [27] [28] 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. [29] Several tanning activators have used different forms of psoralen, which are known to be photocarcinogenic. [30] [31] [32] Health authorities have banned psoralen since July 1996. [33]
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. Parasols and long sleeves were typically worn, even at beaches. [34] By the 1920s, however, a cultural transformation took place, and tan skin became the ideal. [34]
By the early 20th century, therapeutic benefits of sunlight were advertised to the public. [35] In 1903, Niels Finsen was awarded the Nobel Prize in Medicine for his “Finsen Light Therapy”. [36] The therapy was a cure for diseases such as lupus vulgaris and rickets. 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 to test the wider health benefits of "heliotherapy", [37] and by 1913 "sunbathing" was referred to as a desirable activity for the leisured class. Shortly thereafter, in the 1920s, fashion-designer Coco Chanel accidentally got sunburnt while visiting the French Riviera. 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, a "caramel-skinned" singer in Paris, and idolized her darker skin. These two women were leading figures of the transformation that tan skin underwent, in which it became perceived as fashionable, healthy, and luxurious. [38] [39] [40] Jean Patou capitalized on the new tanning fad, launching the first sun tan oil "Huile de Chaldee" in 1927. [41] Just before the 1930s, sunlight therapy became a popularly subscribed cure for almost every ailment from simple fatigue to tuberculosis. In the 1940s, advertisements encouraging sunbathing began to appear in women's magazines. At the same time, swimsuits' skin coverage began decreasing, with the bikini radically changing swimsuit style after it made its appearance in 1946. In the 1950s, baby oil was commonly used to increase tanning.
Coppertone, in 1953, marketed its sunscreen with a drawing of a young 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. [42] In the latter part of the 1950s, silver metallic reflectors were common to enhance one's tan. [43] In 1962, sunscreen commenced to be SPF rated, although SPF labeling in the US was not standardized by the FDA until 1978. In the 1970s, Mattel introduced Malibu Barbie, which had tanned skin and further popularized sun tanning among women. [44] [45]
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, [46] 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. [47] 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 masks were becoming popular items to wear at the beach in order to protect the wearer's face from the effects of sunlight. [48] 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. [49] [50] [51]
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 that are based on dihydroxyacetone (DHA); [52] or cosmetics such as bronzers.[ citation needed ] 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” that is offered by spas, salons, and tanning businesses. [53] Spray tanning does not involve a color being sprayed on the body, instead it uses a colorless chemical that reacts with proteins in the top layer of the skin, resulting in a brown color.[ citation needed ]
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 as daylight when the Sun is above the horizon. When direct solar radiation is not blocked by clouds, it is experienced as sunshine, a combination of bright light and radiant heat (atmospheric). When blocked by clouds or reflected off other objects, sunlight is diffused. Sources estimate a global average of between 164 watts to 340 watts per square meter over a 24-hour day; this figure is estimated by NASA to be about a quarter of Earth's average total solar irradiance.
Ultraviolet (UV) light is electromagnetic radiation of wavelengths of 10–400 nanometers, shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight, and constitutes about 10% of the total electromagnetic radiation output from the Sun. It is also produced by electric arcs, Cherenkov radiation, and specialized lights, such as mercury-vapor lamps, tanning lamps, and black lights.
Human skin color ranges from the darkest brown to the lightest hues. Differences in skin color among individuals is caused by variation in pigmentation, which is the result of genetics, exposure to the sun, disorders, or some combination thereof. Differences across populations evolved through natural selection or sexual selection, because of social norms and differences in environment, as well as regulations of the biochemical effects of ultraviolet radiation penetrating the skin.
Melanocytes are melanin-producing neural crest-derived cells located in the bottom layer of the skin's epidermis, the middle layer of the eye, the inner ear, vaginal epithelium, meninges, bones, and heart found in many mammals and birds. Melanin is a dark pigment primarily responsible for skin color. Once synthesized, melanin is contained in special organelles called melanosomes which can be transported to nearby keratinocytes to induce pigmentation. Thus darker skin tones have more melanosomes present than lighter skin tones. Functionally, melanin serves as protection against UV radiation. Melanocytes also have a role in the immune system.
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. It occurs when skin cells grow uncontrollably, forming malignant tumors. The primary cause of skin cancer is prolonged exposure to ultraviolet (UV) radiation from the sun or tanning devices. Skin cancer is the most commonly diagnosed form of cancer in humans. There are three main types of skin cancers: basal-cell skin cancer (BCC), squamous-cell skin cancer (SCC) and melanoma. The first two, along with a number of less common skin cancers, are known as nonmelanoma skin cancer (NMSC). Basal-cell cancer grows slowly and can damage the tissue around it but is unlikely to spread to distant areas or result in death. It often appears as a painless raised area of skin that may be shiny with small blood vessels running over it or may present as a raised area with an ulcer. Squamous-cell skin cancer is more likely to spread. It usually presents as a hard lump with a scaly top but may also form an ulcer. Melanomas are the most aggressive. Signs include a mole that has changed in size, shape, color, has irregular edges, has more than one color, is itchy or bleeds.
Sunscreen, also known as sunblock, sun lotion or sun cream, is a photoprotective topical product for the skin that helps protect against sunburn and prevent skin cancer. Sunscreens come as lotions, sprays, gels, foams, sticks, powders and other topical products. Sunscreens are common supplements to clothing, particularly sunglasses, sunhats and special sun protective clothing, and other forms of photoprotection.
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 horizontal tanning bed, also known as a sunbed or solarium. Vertical devices are known as tanning booths or stand-up sunbeds.
Dihydroxyacetone, also known as glycerone, is a simple saccharide with formula C
3H
6O
3.
Sunless tanning, also known as UV filled tanning, self tanning, spray tanning, or fake tanning, refers to the effect of a suntan without exposure to the Sun. Sunless tanning involves the use of oral agents (carotenids), or creams, lotions or sprays applied to the skin. Skin-applied products may be skin-reactive agents or temporary bronzers (colorants).
PUVA is an ultraviolet light therapy treatment for skin diseases: vitiligo, eczema, psoriasis, graft-versus-host disease, mycosis fungoides, large plaque parapsoriasis, and cutaneous T-cell lymphoma, using the sensitizing effects of the drug psoralen. The psoralen is applied or taken orally to sensitize the skin, then the skin is exposed to UVA.
Pyrimidine dimers represent molecular lesions originating from thymine or cytosine bases within DNA, resulting from photochemical reactions. These lesions, commonly linked to direct DNA damage, are induced by ultraviolet light (UV), particularly UVC, result in the formation of covalent bonds between adjacent nitrogenous bases along the nucleotide chain near their carbon–carbon double bonds, the photo-coupled dimers are fluorescent. Such dimerization, which can also occur in double-stranded RNA (dsRNA) involving uracil or cytosine, leads to the creation of cyclobutane pyrimidine dimers (CPDs) and 6–4 photoproducts. These pre-mutagenic lesions modify the DNA helix structure, resulting in abnormal non-canonical base pairing and, consequently, adjacent thymines or cytosines in DNA will form a cyclobutane ring when joined together and cause a distortion in the DNA. This distortion prevents DNA replication and transcription mechanisms beyond the dimerization site.
UV-B lamps are lamps that emit a spectrum of ultraviolet light with wavelengths ranging from 290–320 nanometers. This spectrum is also commonly called the biological spectrum due to the human body's sensitivity to light of such a wavelength. UV-B light does not tan the skin very much, compared to the UV-A lamps that are used in tanning beds.
Tanning activators are chemicals that increase the effect of UV-radiation on the human skin.
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 other animals include red or reddish skin that is hot to the touch or painful, general fatigue, and mild dizziness. Other symptoms include blistering, peeling skin, swelling, itching, and nausea. Excessive UV radiation is the leading cause of (primarily) non-malignant skin tumors, which in extreme cases can be life-threatening. Sunburn is an inflammatory response in the tissue triggered by direct DNA damage by UV radiation. When the cells' DNA is overly damaged by UV radiation, type I cell-death is triggered and the tissue is replaced.
Photoaging or photoageing is a term used for the characteristic changes to skin induced by chronic UVA and UVB exposure. Tretinoin is the best studied retinoid in the treatment of photoaging.
Exposure of skin to ultraviolet radiation from sunlight presents both positive and negative health effects. On the positive side, UV exposure enables the synthesis of vitamin D3, which is essential for bone health and potentially plays a role in inhibiting certain cancers. While vitamin D can also be obtained through dietary supplements, UV exposure offers benefits such as enhanced subdermal nitric oxide production and improved endorphin levels, which are not achievable through supplementation alone. Additionally, exposure to visible light supports melatonin synthesis, maintains circadian rhythms, and reduces the risk of seasonal affective disorder.
Solumbra is a line of sun protection clothing and patented fabric that was introduced in 1992.
Dark skin is a type of human skin color that is rich in melanin pigments. People with dark skin are often referred to as black people, although this usage can be ambiguous in some countries where it is also used to specifically refer to different ethnic groups or populations.
The Sunscreen Innovation Act is a 2014 law that amended the Federal Food, Drug, and Cosmetic Act to establish an expedited process for the review and approval of over-the-counter (OTC) sunscreens. The US Food and Drug Administration (FDA) had not approved a new active ingredient in sunscreen since 1999, despite some sunscreens having been approved and used overseas for a decade. The new law gave the FDA one year to respond to the existing backlog of sunscreen ingredient approval requests, and then 18 months to reply to any future applications.
Skin cancer in Australia kills over 2,000 each year, with more than 750,000 diagnosed and treated. Tanning became embedded in Australian culture and proved to be a controversial issue because of its popularity among teens and solarium users, despite correlations between tanning and an increased risk of developing melanoma. Australia experienced relative success through skin cancer prevention campaigns started in the 1980s and continued to invest and promote awareness through government-funded mass media strategies. Although Australia has one of the highest national rates of skin cancer, mortality trends in melanoma stabilized.
A UVB-induced tan provides minimal sun protection, equivalent to an SPF of about 3.
Harris investigated the history of the parasol... everywhere ordinary people were forbidden to protect themselves with such devices "pallid skin became a marker of upper-class status". At the beginning of the 20th Century, in the United States, lighter-skinned people avoided the sun. ... Tanned skin was considered lower class...But by the 1920s, a cultural transformation in favor of sun tanning took place.
{{cite web}}: CS1 maint: unfit URL (link)By the 1920s, the therapeutic effect of the sun was widely promoted, and two well-publicized French personalities gave "tanning" a fashion boost. Coco Chanel, of designer fame, returned to Paris after a cruise on the Duke of Westminster's yacht with a tan that became all the rage. And the natural caramel skin color of singer Josephine Baker made women all over the world try to emulate her skin tone.
{{cite web}}: CS1 maint: unfit URL (link)In 1920s France, the caramel-skinned entertainer Josephine Baker became a Parisian idol. Concurrently, fashion designer Coco Chanel was "bronzed" while cruising on a yacht. A winter tan became a symbol of the leisure class and showed you could afford to travel to exotic climates.
The tanning industry has grown about 25 percent over the past six years, according to the Indoor Tanning Association. In the United States, about 25,000 free-standing tanning salons employ 160,000 people and generate more than $5 billion in annual revenue, the association said.
permits 40% of the sun's ultraviolet rays
{{cite news}}: CS1 maint: unfit URL (link)80 per cent of UV rays... a stretchy yarn described as 'a chicken wire mesh material'
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