Sunscreen (also known as sunblock, suntan lotion) is a lotion, spray or other topical product that is intended to protect the skin from the sun's ultraviolet (UV) radiation. The use of sunscreen does reduce sunburn and other skin damages which are caused by direct DNA damage. However the effect of sunscreen-use on the incidences of malignant melanoma - which is caused by the indirect DNA damage - is still under dispute.^[1][2] This dispute arose from the fact that the epidemiological studies which suggest a positive correlation between sunscreen use and melanoma^{[3][4][5][6][7][8][9][10]} outnumber those which show any protective effect.^[11][12][13] (see aswell Epidemiology of melanoma and sunscreen) A lotion is a low- to medium-viscosity medicated or non-medicated topical preparation intended for application to unbroken skin. ... In medicine, a topical medication is applied to body surfaces such as the skin or mucous membranes such as the vagina, nasopharynx, or the eye. ... Sol redirects here. ... For other uses, see Ultraviolet (disambiguation). ... Melanoma is a malignant tumor of melanocytes. ...

Many medical doctors blame the absence of UVA filters for the increased melanoma risk found for sunscreen users. They claim that sunscreens which protect against both UVB and UVA will result in a protective effect against melanoma, too. Other researchers blame the penetration of sunscreen into the skin and the associated harmful effects on the living tissue.^[14] For other uses, see Ultraviolet (disambiguation). ... For other uses, see Ultraviolet (disambiguation). ...

Most sunscreens work by containing either an organic chemical compound that absorbs ultraviolet light (such as oxybenzone) or an opaque material that reflects light (such as titanium dioxide, zinc oxide), or a combination of both. Typically, absorptive materials are referred to as chemical blocks, whereas opaque materials are mineral or physical blocks. Organic chemistry is a specific discipline within chemistry which involves the scientific study of the structure, properties, composition, reactions, and preparation (by synthesis or by other means) of chemical compounds consisting primarily of carbon and hydrogen, which may contain any number of other elements, including nitrogen, oxygen, the halogens as... Oxybenzone is a chemical used in sunscreen to block UVB. It is a derivative of Benzophenone. ... Flash point non-flammable Related Compounds Other cations Titanium(II) oxide Titanium(III) oxide Titanium(III,IV) oxide Zirconium dioxide Hafnium dioxide Except where noted otherwise, data are given for materials in their standard state (at 25 Â°C, 100 kPa) Infobox disclaimer and references Titanium dioxide, also known as titanium... Zinc oxide is a chemical compound with formula ZnO. It is nearly insoluble in water but soluble in acids or alkalis. ...

How does sunscreen work?

Sunscreen is a topically applied cosmetic product. The desireable site of action is restricted to the skin surface or within only the uppermost layers of the stratum corneum. The stratum corneum consists of dead cells and so the sunscreen ingredients are not in contact with viable tissue. It is often assumed that little or none of a topically applied substance is absorbed into the body.^[15] As long as these requirements are met the sunscreen acts as an inert filter, reducing the intensity of UV-radiation that acts on the deeper tissue of the skin. From a medical point of view, the penetration of the active ingredients into the deeper layers of skin is highly undesireable. [Kerry Hanson skin penetration] The stratum corneum (the horny layer) is the outermost layer of the epidermis (the outermost layer of the skin). ...

tanning and sunscreen

In his book: "Physician's guide to sunscreens" Nicholas J. Lowe pointed out, that one of the reasons for customers to reject sunscreen use is the reduction of tanning that is associated with good sunscreen protection.(chapter 7 page 81)^[16] 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.^[17][18][19] Despite the obvious photocarcinogenic effects the authorities dissallowed Psoralen only in July 1996.^[20] Psoralen (also called psoralene) is the parent compound in a family of natural products known as furocoumarins. ...

Importantly the tanning activators increase the measured SPF-factor, because it is a measurement that is performed on a film of sunscreen which is not in contact with living tissue. However the tan-activating properties rely on the penetration into the skin and the photochemical reactions that they perform there.

Recent legal changes concerning sunscreen

In August 2007, FDA proposed to disallow manufacturer claims on bottles that using sunscreens prevents cancer and to change SPF to refer to Sunburn Protection Factor instead of Sun Protection Factor (FDA proposed changes). This was done due to the epidemiological results in conjunction with some mechanistic studies which show that sunscreens prevent inflammation only and not necessarily the causes of melanoma.
However, the FDA is proposing to retain the language which states "UV exposure from the sun increases the risk of skin cancer, premature skin aging, and other skin damage. It is important to decrease UV exposure by limiting time in the sun, wearing protective clothing, and using a sunscreen" (page 49073). In these comments, the FDA also noted that DHA "appears to be a potent inducer of thymine dimers, premutagenic deoxyribonucleic acid (DNA) lesions" and "FDA has tentatively concluded that the available evidence fails to show that sunscreen use alone helps prevents skin cancer or premature skin aging." (page 49079)

Testing for photocarcinogenic effects

Until 1978 it was not compulsory in any country to test sunscreens for photocarcinogenic effects.^[21] The only country which made such tests compulsory is the USA.^[22] This new safety regulation came into effect in 1978, and from the 16 sunscreen ingredients that are allowed on the US-market today 13 were introduced before the tests for photocarcinogenic properties were introduced. In the 30 years since 1978 only 3 new agents were developed that were good enough to overcome this obstacle.^[21]

Dosing

Dosing for sunscreen can be calculated using the formula for body surface area and subsequently subtracting the area covered by clothing that provides effective UV protection. The dose used in FDA sunscreen testing is 2 mg/cm².^[23] Provided one assumes an "average" adult build of height 5 ft 4 in (163 cm) and weight 150 lb (68 kg) with a 32 in (82 cm) waist, that adult wearing a bathing suit covering the groin area should apply 29 g (approximately 1 oz) evenly to the uncovered body area. Considering only the face, this translates to about 1/4 to 1/3 of a teaspoon for the average adult face. In physiology and medicine, the body surface area (BSA) is the measured or calculated surface of a human body. ... “FDA” redirects here. ...

Contrary to the common advice that sunscreen should be reapplied every 2–3 hours, some research has shown that the best protection is achieved by application 15–30 minutes before exposure, followed by one reapplication 15–30 minutes after the sun exposure begins. Further reapplication is only necessary after activities such as swimming, sweating, and rubbing.^[24]

However, more recent research at the University of California, Riverside indicates that sunscreen needs to be reapplied within 2 hours in order to remain effective. Not reapplying could even cause more cell damage than not using sunscreen at all, due to the release of extra free radicals from those sunscreen chemicals which were absorbed into the skin.^[14] The University of California, Riverside, commonly known as UCR or UC Riverside, is a public, coeducational university and one of ten campuses of the University of California. ... In chemistry, radicals (often referred to as free radicals) are atomic or molecular species with unpaired electrons on an otherwise open shell configuration. ...

History

The first effective sunscreen may have been developed by chemist Franz Greiter in 1938. The product, called Gletscher Crème (Glacier Cream), subsequently became the basis for the company Piz Buin (named in honor of the place Greiter allegedly obtained the sunburn that inspired his concoction), which today is a well-known marketer of sunscreen products. Some internet articles suggest that Gletscher Crème had a sun protection factor of 2, although a research citation is not readily available online. Year 1938 (MCMXXXVIII) was a common year starting on Saturday (link will display the full calendar) of the Gregorian calendar. ...

The first widely used sunscreen was produced by Benjamin Greene, an airman and later a pharmacist, in 1944. The product, Red Vet Pet (for red veterinary petrolatum), had limited effectiveness, working as a physical blocker of ultraviolet radiation. It was a disagreeable red, sticky substance similar to petroleum jelly. This product was developed during the height of World War II, when it was likely that the hazards of sun overexposure were becoming apparent to soldiers in the Pacific and to their families at home. The mortar and pestle is an international symbol of pharmacists and pharmacies. ... Year 1944 (MCMXLIV) was a leap year starting on Saturday (link will display full calendar) of the Gregorian calendar. ... Combatants Allied powers: China France Great Britain Soviet Union United States and others Axis powers: Germany Italy Japan and others Commanders Chiang Kai-shek Charles de Gaulle Winston Churchill Joseph Stalin Franklin Roosevelt Adolf Hitler Benito Mussolini Hideki Tōjō Casualties Military dead: 17,000,000 Civilian dead: 33,000...

Franz Greiter is credited with introducing the concept of Sun Protection Factor (SPF) in 1962, which has become a worldwide standard for measuring the effectiveness of sunscreen when applied at an even rate of 2 milligrams per square centimeter (mg/cm²). Some controversy exists over the usefulness of SPF measurements, especially whether the 2 mg/cm² application rate is an accurate reflection of people’s actual use. Sunscreen or sunblock is a lotion that is applied to reduce skin damage by blocking ultraviolet radiation from the sun. ...

Newer sunscreens have been developed with the ability to withstand contact with water and sweat. Impact from a water drop causes an upward rebound jet surrounded by circular capillary waves. ... SWEAT is an OLN/TSN show hosted by Julie Zwillich that aired in 2003-2004. ...

Measurements of sunscreen protection

Sun protection factor

The SPF of a sunscreen is a laboratory measure of the effectiveness of sunscreen; the higher the SPF, the more protection a sunscreen offers against UV-B (the ultraviolet radiation that causes sunburn). The SPF indicates the time a person can be exposed to sunlight before getting sunburn with a sunscreen applied relative to the time they can be exposed without sunscreen. For example, someone who would burn after 12 minutes in the sun would expect to burn after 2 hours (120 min) if protected by a sunscreen with SPF 10. In practice, the protection from a particular sunscreen depends on factors such as:

• The skin type of the user.
• The amount applied and frequency of re-application.
• Activities in which one engages (for example, swimming leads to a loss of sunscreen from the skin).
• Amount of sunscreen the skin has absorbed.

The SPF is an imperfect measure of skin damage because invisible damage and skin aging is also caused by the very common ultraviolet type A, which does not cause reddening or pain. Conventional sunscreen does not block UVA as effectively as it does UVB, and an SPF rating of 30+ may translate to significantly lower levels of UVA protection according to a 2003 study. According to a 2004 study, UVA also causes DNA damage to cells deep within the skin, increasing the risk of malignant melanomas.^[25] Even some products labeled "broad-spectrum UVA/UVB protection" do not provide good protection against UVA rays.^[26] The best UVA protection is provided by products that contain zinc oxide, avobenzone, and ecamsule. Titanium dioxide probably gives good protection, but does not completely cover the entire UV-A spectrum.^[27] Human skin color can range from very dark brown to nearly colorless (appearing pinkish white due to the blood in the skin) in different people. ... For other uses, see Ultraviolet (disambiguation). ... The structure of part of a DNA double helix Deoxyribonucleic acid, or DNA, is a nucleic acid molecule that contains the genetic instructions used in the development and functioning of all known living organisms. ... Melanoma is a malignant tumor of melanocytes. ... Zinc oxide is a chemical compound with formula ZnO. It is nearly insoluble in water but soluble in acids or alkalis. ... Avobenzone (trade names Parsol® 1789, Eusolex® 9020, Escalol® 517 and others, INCI Butyl Methoxydibenzoylmethane) is an oil soluble ingredient used in sunscreen products to absorb both UVA and UVB rays. ... Ecamsule (USAN, trade name Mexoryl® SX, INCI Terephthalylidene Dicamphor Sulfonic Acid) is a chemical which is added to many sunscreens to filter out UVA rays. ... Flash point non-flammable Related Compounds Other cations Titanium(II) oxide Titanium(III) oxide Titanium(III,IV) oxide Zirconium dioxide Hafnium dioxide Except where noted otherwise, data are given for materials in their standard state (at 25 Â°C, 100 kPa) Infobox disclaimer and references Titanium dioxide, also known as titanium...

Due to consumer confusion over the real degree and duration of protection offered, labeling restrictions are in force in several countries. In the United States in 1999, the Food and Drug Administration (FDA) decided to institute the labelling of SPF 30+ for sunscreens offering more protection, and a similar restriction applies in Australia. This was done to discourage companies from making unrealistic claims about the level of protection offered (such as "all day protection"),^[28] and because an SPF over 30 does not provide significantly better protection.^{[citation needed]} In the EU sunscreens are limited to SPF 50+, indicating an SPF of 60 or higher.^[29] “FDA” redirects here. ...

UV-B sunlight spectrum (on a summer day in the Netherlands), along with the CIE Erythemal action spectrum. The effective spectrum is the product of the former two.

The SPF can be measured by applying sunscreen to the skin of a volunteer and measuring how long it takes before sunburn occurs when exposed to an artificial sunlight source. In the US, such an in vivo test is required by the FDA. It can also be measured in vitro with the help of a specially designed spectrometer. In this case, the actual transmittance of the sunscreen is measured, along with the degradation of the product due to being exposed to sunlight. In this case, the transmittance of the sunscreen must be measured over all wavelengths in the UV-B range (290–350 nm), along with a table of how effective various wavelengths are in causing sunburn (the erythemal action spectrum) and the actual intensity spectrum of sunlight (see the figure). Such in vitro measurements agree very well with in vivo measurements.^[30] Image File history File links Erythemal_action_spectrum. ... Image File history File links Erythemal_action_spectrum. ... In vivo (Latin for (with)in the living). ... “FDA” redirects here. ... In vitro (Latin: within the glass) refers to the technique of performing a given experiment in a test tube, or, generally, in a controlled environment outside a living organism. ... Spectrometer A spectrometer is an optical instrument used to measure properties of light over a specific portion of the electromagnetic spectrum, typically used in spectroscopic analysis to identify materials. ... In the fields of optics and spectroscopy, transmittance is the fraction of incident light at a specified wavelength that passes through a sample. ... This article deals with the general meaning of spectrum and the history of its use. ...

Mathematically, the SPF is calculated from measured data as

where E(λ) is the solar irradiance spectrum, A(λ) the erythemal action spectrum, and MPF(λ) the monochromatic protection factor, all functions of the wavelength λ. The MPF is roughly the inverse of the transmittance at a given wavelength.

The above means that the SPF is not simply the inverse of the transmittance in the UV-B region. If that were true, then applying two layers of SPF 5 sunscreen would be equivalent to SPF 25 (5 times 5). The actual combined SPF is always lower than the square of the single-layer SPF.

Measurements of UVA protection

Persistent Pigment Darkening (PPD), Immediate Pigment Darkening (IPD), Boots Star System, Japanese PA system

The Persistent Pigment Darkening (PPD) method is a method of measuring UVA protection, similar to the SPF method of measuring UVB light protection. Theoretically, a sunscreen with a PPD rating of 10 should allow you to endure 10 times as much UVA as you would without protection.

The PPD is used as part of guidelines for EU sunscreens to provide the consumer with a minimum of UVA protection in relation to the SPF. The PPD should be at least 1/3 of the SPF to carry the UVA seal. The implementation of this seal is in its fase-in period, so a sunscreen without may already offer this protection. ^[31]

Star rating system

In the UK and Ireland, a star rating system is used to describe the ratio of UVA to UVB protection offered by sun screen creams and sprays. Invented by Dr Diffey of the Boots Company in Nottingham UK, it has been adopted by most companies marketing these products in the UK. It should not be confused with SPF which is measured with reference to burning and UVB. One star products provide the least ratio of UVA protection, five star products are the best.

Active ingredients

The principal ingredients in sunscreens are usually aromatic molecules conjugated with carbonyl groups. This general structure allows the molecule to absorb high-energy ultraviolet rays and release the energy as lower-energy rays, thereby preventing the skin-damaging ultraviolet rays from reaching the skin. So, upon exposure to UV light, most of the ingredients (with the notable exception of avobenzone) do not undergo significant chemical change, allowing these ingredients to retain the UV-absorbing potency without significant photo-degradation.^[23] Aromaticity is a chemical property in which a conjugated ring of unsaturated bonds, lone pairs, or empty orbitals exhibit a stabilization stronger than would be expected by the stabilization of conjugation alone. ... A chemically conjugated system, is a system of atoms covalently bonded with alternating single and double bonds (e. ... Carbonyl group In organic chemistry, a carbonyl group is a functional group composed of a carbon atom double-bonded to an oxygen atom : C=O. The term carbonyl can also refer to carbon monoxide as a ligand in an inorganic or organometallic complex (a metal carbonyl, e. ... Avobenzone (trade names Parsol® 1789, Eusolex® 9020, Escalol® 517 and others, INCI Butyl Methoxydibenzoylmethane) is an oil soluble ingredient used in sunscreen products to absorb both UVA and UVB rays. ... Photo-degradation is degradation by means of radiant energy such as light. ...

The following are the FDA allowable active ingredients in sunscreens:

• p-Aminobenzoic acid (PABA) up to 15 %.
• Avobenzone up to 3%.
• Cinoxate up to 3%.
• Dioxybenzone up to 3%.
• Homosalate up to 15%.
• Methyl anthranilate up to 5%.
• Octocrylene up to 10%.
• Octyl methoxycinnamate (Octinoxate) up to 7.5%.
• Octyl salicylate (Octisalate) up to 5%.
• Oxybenzone up to 6%.
• Padimate O up to 8%.
• Phenylbenzimidazole sulfonic acid (Ensulizole) up to 4%.
• Sulisobenzone up to 10%.
• Titanium dioxide up to 25%.
• Trolamine salicylate up to 12 %.
• Zinc oxide up to 25%.

Recently FDA approved: Para-Aminobenzoic acid (PABA) is a chemical used in sunscreen that is an essential nutrient for some bacteria. ... Avobenzone (trade names Parsol® 1789, Eusolex® 9020, Escalol® 517 and others, INCI Butyl Methoxydibenzoylmethane) is an oil soluble ingredient used in sunscreen products to absorb both UVA and UVB rays. ... Cinoxate is an organic compound used as an ingredient in some types of sunscreens. ... Categories: Stub ... Homosalate is an organic compound used in some sunscreens. ... Methyl anthranilate, also known as MA, methyl 2-aminobenzoate or carbomethoxyaniline, is an ester of anthranilic acid. ... Octocrylene is an organic compound used as an ingredient in sunscreens and cosmetics. ... Chemical ingredient for many sunscreens to block UV-B radiation of the sun. ... Disclaimer and references Octyl salicylate is an organic compound used as an ingredient in sunscreens and cosmetics. ... Oxybenzone is a chemical used in sunscreen to block UVB. It is a derivative of Benzophenone. ... Disclaimer and references Padimate O is an organic compound that is an ingredient in some sunscreens. ... Phenylbenzimidazole sulfonic acid (C13H10N2O3S) is a common sunscreen agent. ... Flash point non-flammable Related Compounds Other cations Titanium(II) oxide Titanium(III) oxide Titanium(III,IV) oxide Zirconium dioxide Hafnium dioxide Except where noted otherwise, data are given for materials in their standard state (at 25 Â°C, 100 kPa) Infobox disclaimer and references Titanium dioxide, also known as titanium... Trolamine salicylate is not a true counterirritant, but can be used as a topical analgesic in concentrations greater than 10%. One benefit of this topical analgesic is that it has no odor, in contrast to other products such as menthol (Ben-Gay) or Capsaicin (Zostrix). ... Zinc oxide is a chemical compound with formula ZnO. It is nearly insoluble in water but soluble in acids or alkalis. ...

• Mexoryl SX (USAN Ecamsule, INCI Terephthalylidene Dicamphor Sulfonic Acid) - UVA absorber used in combination with other ingredients for UVB

Others approved within the EU^[32] and other parts of the world^[33] include: Mexoryl is a chemical molecule which is added to many sunscreens to filter out UVA rays. ... There have been a number of attempts to coin an alternative to American as an adjective (a demonym) for United States nationals. ... Ecamsule (USAN, trade name Mexoryl® SX, INCI Terephthalylidene Dicamphor Sulfonic Acid) is a chemical which is added to many sunscreens to filter out UVA rays. ... The International Nomenclature of Cosmetic Ingredients, abbreviated INCI, is a system of names for waxes, oils, pigments, chemicals, and other ingredients of cosmetics, soaps, and the like, based on scientific names and other Latin and English words. ...

• 4-Methylbenzylidene camphor ((INCI), USAN Enzacamene)
• Tinosorb M (USAN Bisoctrizole, INCI Methylene Bis-Benzotriazolyl Tetramethylbutylphenol)
• Tinosorb S (USAN Bemotrizinol, INCI Bis-Ethylhexyloxyphenol Methoxyphenyl Triazine)
• Mexoryl XL (INCI Drometrizole Trisiloxane)
• Neo Heliopan AP (USAN Bisdisulizole Disodium, INCI Disodium Phenyl Dibenzimidazole Tetrasulfonate)
• Uvinul A Plus (INCI Diethylamino Hydroxybenzoyl Hexyl Benzoate)
• Uvinul T 150 (USAN Octyl Triazone, INCI Ethylhexyl Triazone)
• Uvasorb HEB (USAN Iscotrizinol, INCI Diethylhexyl Butamido Triazone)
• Parsol SLX (INCI Polysilicone-15)
• Amiloxate ((USAN), INCI Isoamyl p-Methoxycinnamate)

A lot of the ingredients not approved by the FDA are relatively new and developed to absorb UVA.^[34] 4-Methylbenzylidene camphor, short 4-MBC, also 3-(4-Methylbenzylidene)bornan-2-one, or 3-(4-Methylbenzylidene)-dl-camphor is an organic camphor derivative that is used in the cosmetic industry for its ability to protect the skin against UV, specifically UV B radiation. ... Bisoctrizole (USAN, trade name Tinosorb® M, INCI Methylene Bis-Benzotriazolyl Tetramethylbutylphenol) is a chemical which is added to sunscreens to absorb UV rays. ... Bemotrizinol (USAN, trade name Tinosorb® S, INCI Bis-Ethylhexyloxyphenol Methoxyphenyl Triazine) is an oil soluble chemical which is added to sunscreens to absorb UV rays. ... Bisdisulizole disodium (USAN[1], Neo Heliopan® AP, INCI disodium phenyl dibenzimidazole tetrasulfonate) is a water soluble chemical which is added to sunscreens to absorb UVA rays. ...

Melanin

The hormone alpha-melanocyte stimulating hormone is made when the body is exposed to sunlight and is responsible for the development of the pigment melanin. Research is being done to create stable artificial forms of the hormone. A promising candidate, melanotan, might be useful in the prevention of skin cancer, by causing tanning without the need for exposure to dangerous levels of UV. For other uses, see Hormone (disambiguation). ... Melanocyte-stimulating hormone (MSH) is a peptide hormone produced by cells in the intermediate lobe of the pituitary gland. ... Broadly, melanin is any of the polyacetylene, polyaniline, and polypyrrole blacks and browns or their mixed copolymers. ... Melanotan 1 and melanotan II are both analogs of the peptide hormone alpha-melanocyte stimulating hormone (α-MSH) that tend to induce skin tanning. ...

Possible adverse effects

Main article: Sunscreen controversy

Some individuals can have mild to moderate allergic reactions to certain ingredients in sunscreen, particularly the chemical benzophenone, which is also known as phenyl ketone, diphenyl ketone, or benzoylbenzene. It is not clear how much of benzophenone is absorbed into the bloodstream, but trace amounts can be found in urinalysis after use. Allergy is an abnormal reaction to a substance foreign to the body that is acquired, predictable and rapid. ... Benzophenone, also known as diphenylmethanone, phenyl ketone, diphenyl ketone, or benzoylbenzene. ... Red blood cells (erythrocytes) are present in the blood and help carry oxygen to the rest of the cells in the body Blood is a circulating tissue composed of fluid plasma and cells (red blood cells, white blood cells, platelets). ... A urinalysis (or UA) is an array of tests performed on urine and one of the most common methods of medical diagnosis. ...

Sunscreens are effective in reducing sunburn, but not necessarily the risk of cancer. A letter to the editor published in April 1992, entitled "Could sunscreens increase melanoma risk?" reported that the greatest increase in melanoma occurred in those regions where sunscreen use is most prevalent.^[35] The authors point out that "the SPF of sunscreens concerns solely their ability to absorb ultraviolet B (UV-B) light. Even sunscreens with high SPF factors can be completely transparent to ultraviolet A (UV-A), which includes 90 to 95% of ultraviolet light. UV-A blocking ingredients, which have commonly been added to most sunscreens since 1989, block only half the UV-A spectrum and provide a protection factor against delayed UV-A induced erythema of only 1.7 at usual concentrations. Both UV-A and UV-B have been shown to mutate DNA and promote skin cancers in animals. UV-A also penetrates deeper into the skin than UV-B... two studies suggest that sunscreens may not be effective in preventing skin cancer. A large case-control study showed higher risks of melanoma in men who used sunscreens, and a large prospective study showed a higher incidence of basal cell carcinoma in women who used sunscreens." Melanoma is a malignant tumor of melanocytes which are found predominantly in skin but also in the bowel and the eye (see uveal melanoma). ... Basal cell carcinoma (BCC) is the most common skin cancer. ...

Recently, there has been increased attention to the possibility of adverse health effects associated with the synthetic compounds in most sunscreens.^[36] Recent studies found that some sunscreens generate harmful compounds that might promote skin cancer. The three commonly used ultraviolet (UV) filters -- octylmethoxycinnamate, benzophenone 3, and octocrylene -- eventually soak into the deeper layers of the skin after their application, leaving the top skin layers vulnerable to sun damage. UV rays absorbed by the skin can generate harmful compounds called reactive oxygen species (ROS), which can cause skin cancer and premature aging. The researchers found that once the filters in sunscreen soak into the lower layers of skin, the filters react with UV light to create more damaging ROS.^[14] To reduce ROS generation and damage, the researchers recommend reapplying the sunscreen often, which will replenish the sunscreen which has penetrated the skin. Future possibilities may include the development of sunscreens which stay at the surface of the skin, or mixing sunscreens with antioxidants that can neutralize ROS.^[37] In chemistry, chemical synthesis is purposeful execution of chemical reactions in order to get a product, or several products. ... Reactive oxygen species (ROS) include oxygen ions, free radicals and peroxides both inorganic and organic. ... For other uses, see Skin (disambiguation). ... Space-filling model of the antioxidant metabolite glutathione. ...

A significant reduction in sun exposure inhibits the production of vitamin D. The use of sunscreen with a sun protection factor (SPF) of 8 inhibits more than 95% of vitamin D production in the skin.^[38] However, excessive sun exposure has been conclusively linked to some forms of skin cancer and signs of premature aging. Season, geographic latitude, time of day, cloud cover, smog, skin type, and sunscreen all have an effect on vitamin D production in the skin.^[39] Fifteen minutes per day of direct exposure to the sun (i.e. without sunscreen) is a generally accepted guideline to follow for optimum vitamin D production.^[40] Vitamin D is a fat soluble vitamin that contributes to the maintenance of normal levels of calcium and phosphorus in the bloodstream. ... Skin cancer is a malignant growth on the skin which can have many causes. ...

See also

• Slip-Slop-Slap - famous Australian sun safety advertising jingle
• "Wear Sunscreen" - a column by Mary Schmich in the form of a speech that became a music single and then made into a music video that became viral on the internet
• Indoor tanning lotion
• Sun protective clothing

Slip-Slop-Slap is the name for a health campaign in Australia exhorting people to slip on a shirt, slop on sunscreen, and slap on a hat when they go out into the sun in order to prevent skin cancer. ... Wear Sunscreen or Sunscreen Speech [1] are the common names of an essay actually called Advice, like youth, probably just wasted on the young written by Mary Schmich and published in the Chicago Tribune as a column in 1997. ... Mary Schmich is a columnist for the Chicago Tribune. ... Viral phenomena are objects or patterns able to replicate themselves or convert other objects into copies of themselves when these objects are exposed to them. ... Typical bottle of tanning lotion. ... // Sun protective clothing is clothing specifically designed for sun protection and is produced from a fabric rated for its level of ultraviolet (UV) protection. ...

References

ISSN, or International Standard Serial Number, is the unique eight-digit number applied to a periodical publication including electronic serials. ... ISSN, or International Standard Serial Number, is the unique eight-digit number applied to a periodical publication including electronic serials. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 161st day of the year (162nd in leap years) in the Gregorian calendar. ...

External links

• FDA rulemaking history for sunscreens

* FDA monograph on sunscreen

* FDA monograph on dosing, mechanism of action, and photodegradation of sunscreen (PDF file)

• Make sure your sunscreen has The Skin Cancer Foundation's Seal of Recommendation
• Environmental Working Group: June 2007 Searchable Sunscreen Safety Database and Report
• Information on what sunscreens are and how they work from The Skin Cancer Foundation
• Sunscreen protection calculator
• Sun Safety for Babies and Children University of Florida/IFAS Extension Department of Family, Youth and Community Sciences
• Article on UV absorbers not yet approved by the FDA
• Radiation protectants and their CAS registry number