sunscreen
American Heritage Dictionary:
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sun·screen
(sŭn'skrēn') 
n.
A preparation, often in the form of a cream or lotion, used to protect the skin from the damaging ultraviolet rays of the sun.
sunscreening sun'screen'ing adj.
n.
A preparation, often in the form of a cream or lotion, used to protect the skin from the damaging ultraviolet rays of the sun.
sunscreening sun'screen'ing adj.
Gale's How Products Are Made:
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How is sunscreen made?
Background
The image of a healthy person today does not necessarily include a deep, dark tan. Research has linked exposure to the sun's ultraviolet rays to skin cancer, premature wrinkles, and other skin problems. While protective clothing such as hats, pants, and long sleeve shirts are the most effective blocks against these damaging rays, sun-screen lotions also provide remarkable protection for the skin.
The light emitted by the sun consists of three frequency bands of radiation: infrared, visible, and ultraviolet. Of the three, only the ultraviolet is harmful to most humans. Ultraviolet (UV) radiation is further divided into three categories: UVA, UVB, and UVC. UVA radiation penetrates the skin without burning the surface layers. These rays can penetrate to a depth of 0.04 inches (1.0 mm) and cause damage to cell membranes and the immune system. UVA radiation has been linked to skin cancers and premature aging and wrinkling of the skin. UVB radiation is responsible for the painful, red burn people get after prolonged exposure to the sun. UVB rays also cause skin cancer and can damage the cornea and lens of the eye. The third category, UVC radiation, is generally absorbed by the earth's atmosphere and is not considered harmful. Sunscreen lotions that provide protection against both UVA and UVB radiation are known as having a broad spectrum of protection.
There are two basic types of sunscreen lotions on the market: products that penetrate the outermost layer of skin to absorb ultraviolet rays, and products which coat the surface of the skin to act as physical barriers to ultraviolet rays. Both of these types are rated with a sun protection factor (SPF), which lets the consumer know how much protection against UVB rays the product provides. The SPF of a product is the ratio of the time required for a person's protected skin to redden after being exposed to sun-light compared to the time required for the same person's unprotected skin to redden. For example, a product with SPF15 means that a person whose unprotected skin would redden in ten minutes can apply the product and stay in the sun 15 times longer, or 150 minutes, before they get a sunburn.
Researchers believed for a long time that UVB rays—the rays that actually cause a sunburn—were solely responsible for all forms of skin cancer. However, recent studies prove that UVA rays are also responsible. Although many sunscreens now contain UVA protectors, there are currently no standards set by the Food and Drug Administration (FDA) for protection against UVA rays. The SPF rating on a product applies only to protection against UVB rays. The FDA requires strict regulations and testing prior to the manufacture of any new sunscreen lotion. Sunscreen producers go through an expensive and lengthy process to get FDA approval. This approval authorizes the manufacturer to produce the exact formulation applied for and is limited to only one SPF rating and one specific usage.
Development and Testing
Today's target market for sunscreens are highly specialized. Sunscreen products are continually being redeveloped to meet the changing needs of specific consumers. For instance, formulations for athletes may contain ingredients which are more waterproof and sweatproof to provide protection for up to eight hours. Athletes may also desire a lotion that feels dry so as not to affect their grip. Children's skins are more sensitive than adults because the outermost layer is thinner. This supports the observation that most sun damage to the skin occurs during childhood and the early teenage years. Sun-screens developed for the children's market tend to contain natural ingredients such as aloe vera and vitamin E.
In the development phase for a new sunscreen, a team of chemists and lab technicians develop the sunscreen formulation from synthetic and natural ingredients. Initial formulations are made in quantities of 10 gallons (38 1) and are stored in stainless steel vats. These initial formulations are tested and finalized before an application to the FDA for approval is made. FDA approval requires further testing which may be done in-house or by an outside laboratory. Examples of the kind of testing required for FDA approval include tests to measure the effective sun protection factor according to FDA guidelines, tests to determine how safe the product is to use on the skin, and tests to measure the waterproof tolerance of a lotion.
Raw Materials
Many combinations of synthetic and natural ingredients may go into the formulation of a single sunscreen. A formulation is generally geared towards a specific SPF rating or the needs of a specific consumer group. Perhaps the best-known synthetic material used for protection against UVA rays is avobenzone, or Parsol 1789, which is used in products worldwide. Broad spectrum protection is provided by other synthetic ingredients such as benzophenone and oxybenzone, which protect by absorbing UV light. PABA (paraaminobenzoic acid) was once a popular UV-absorbing sunscreen ingredient, but it can cause skin irritation in some people and is now replaced by Padimate-O, a derivative of PABA. Other broad spectrum synthetic ingredients are octyl methoxycinnamate and menthyl anthranilate.
Titanium dioxide is a natural mineral and a popular ingredient for broad spectrum protection. Titanium dioxide works by scattering UV light instead of absorbing it. Although not as opaque as zinc oxide, it has a similar whitening effect in the higher SPF ratings. Antioxidants are often combined with titanium dioxide to slow down the oxidation of oils and thereby delay the deterioration of the lotion. Some examples of natural antioxidants are vitamins E and C, rice bran oil and sesame seed oil. Another popular antioxidant in the natural category is green tea. Many newer sunscreen products also contain skin soothing and moisturizing additives such as aloe and chamomile.
The Manufacturing
Process
Sunscreen products may be manufactured, bottled, and shipped from a single facility, or portions of this work may be handled out-side of the company. The fully automated manufacturing process described here uses some of both approaches.
Formulating the lotion
- Water is purified using a method called reverse osmosis. Reverse osmosis extracts pure, fresh water by forcing water under pressure through a semipermeable membrane which separates pure water molecules from salts and other impurities.
- Ingredients are purchased from outside sources and mixed with the purified water according to the recipe of the final formulation. The recipe is recorded on a vat sheet which lists the exact measurements for each ingredient. Measurements are converted from the initial 10-gallon (38 1) recipe used in the development stage to larger quantities for commercial use.
Making the containers
- A blow molding facility manufactures the plastic containers for the sunscreen. In some cases this is done outside of the company. Blow molding is a method in which thermoplastics, plastics which soften when heated and harden when cooled, are extruded into a tube, called a parison, and placed into an open mold. The mold is closed around the heated parison, and the parison is pinched at the bottom to form a seal. Compressed air is blown through the top of the parison which forces the softened plastic to expand to the inside walls of the mold, creating the shape of the container.
- Containers are moved to a printing facility where logos and product information are printed and, in some cases, stamped onto the containers. Stamping embosses thin metal foil onto the surface of the container in the desired shape, usually a logo. The printed or stamped containers are then stored for use when needed.
Filling the containers
- Stainless steel tanks with capacities up to 1,000 gallons (3784 1) are used in the filling process. Filling takes place in a separate, sterile room with a conveyor system of many incoming tracks. Machine operators monitor the automated process. Containers and caps enter the fill room on conveyor tracks. The sunscreen lotion flows from the vats through stainless steel piping to a pressure filling machine which inserts a retractable nozzle into each container and fills it with a measured amount of sunscreen lotion.
Capping the containers
- Most containers are capped automatically along the production line. Some containers include caps with pumps to allow easy dispensing of the sunscreen. These pump caps require manual assembly by operators as the containers leave the fill phase.
Shipping
- The filled and capped containers are boxed in quantities of 12 to be pelletized and secured to a skid by shrink wrapping for transport to distributors.
Byproducts/Waste
Sanitized plastic scraps from the container molding process are reground and used again in molding. Containers which have been through the printing process and have flaws are passed on to other companies and made into products such as patio furniture.
The Future
Researchers look to nature in search of the next wave in sunscreen development. Some plants have natural defenses against the damaging rays of the sun. For example the single-cell alga called Dunaliella Bardawil that thrives in the Dead Sea and the Sinai desert makes its own sunscreen. Scientists at the Weizmann Institute of Science in Rehovot, Israel, isolated the protein that this plant produces when sunlight gets too intense. The protein acts as a solar deflector by funnelling light down to where photosynthesis takes place. Excess light which could interfere with photosynthesis is shunned by a yellow-orange pigment produced by the algae.
The human body also has a natural defense called melanin. Melanin is the brownish-black pigment found in skin and hair. It reflects and absorbs ultraviolet rays to provide a broad spectrum of protection. Dark-skinned people have a higher concentration of melanin and, as a result, have a lower incidence of skin cancer as well as less physical and medical signs of aging skin. Melanin was once painstakingly collected by extraction from exotic sources such as cuttle fish and cost about $3,000 per ounce ($101 per ml). However it can now be made in an inexpensive procedure using fermentation jars. One technology being used as a method of incorporating melanin into sunscreen lotions is to encapsulate it into microsponges which hold the melanin on the surface of the skin where it is most effective. The microsponges are invisible to the eye, and can only be seen under a microscope. Researchers continue to gain approval for the many uses of natural and synthetic melanin as an ingredient in sunscreen formulations.
Where To Learn More
Books
Conry, Tom, ed. Consumer's Guide to Cosmetics. Anchor Press/Doubleday, 1980.
Winter, Ruth. A Consumer's Dictionary of Cosmetic Ingredients. Crown Publishers, 1984.
Periodicals
Bylinsky, Gene. "Mass-Producing Nature's Sunscreen." Fortune, June 1992, p. 131.
Davey, Tom. "Sunscreen Success Gives Biotech New Healthy Glow." San Francisco Business Times, October 1994, p. 8.
Demetrakakes, Pan. "Packaging Patterns Make Mark On Makeup." Packaging, March 1994, pp. 20-21.
Groves, Gordon A. "Toward More Effective UVA Protection." Drug and Cosmetic Industry, August 1994, pp. 37-38.
Kintish, Lisa. "The Battle of The Sun." Soap/Cosmetics/Chemical Specialties For May, May 1993, pp. 42-48.
[Article by: David N. Ford]
Drug Info:
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Sunscreens
Brand names: Banana Boat® Dark Tanning Lotion, Blistex® Ultra Protection, Broad Spectrum Sunscreen SPF 30, Cetaphil® Daily Facial Moisturizer SPF 15, Chap Stick®, Coppertone Sport® Ultra Sweatproof SPF 15, Coppertone Sport® Ultra Sweatproof SPF 30, Coppertone Sport® Ultra Sweatproof SPF 45, Coppertone Sport® Ultra Sweatproof SPF 8, Coppertone®, Eleaf™, Herpecin-L®, Shade UVA Guard®, Sportz Block®
Sunscreens topical dosage forms
What are Sunscreens topical dosage forms?
SUNSCREENS protect your skin from the harmful effects of the sun and help to prevent sunburn. There are 2 different kinds of sunscreens called 'physical sunscreens' and 'chemical sunscreens.' Physical sunscreens reflect the sun's UV radiation. Chemical sunscreens absorb the sun's UV radiation. All physical sunscreens give UVA and UVB protection. All chemical sunscreens give UVB protection. Some chemical sunscreens give both UVA and UVB protection. Limiting the amount of time you spend in the sun and using sunscreens can help prevent wrinkles and skin damage, such as skin cancer.
What should I tell my health care provider before I take this medicine?
They need to know if you have any of these conditions:
• an unusual reaction to sunscreens, PABA, other medicines, foods, dyes, or preservatives
• pregnant or trying to get pregnant
• breast-feeding
How should this medicine be used?
The sun protection factor (SPF) found on the product label tells you how much protection a sunscreen offers. Products with high SPFs give more protection against the sun than products with low SPF. Choose a sunscreen product based on the type of activity in which you are involved, your age, site of application, your skin condition, and your skin type. Ask your pharmacist or health care professional about which sunscreen product is best for you.
Sunscreens are for external use only; apply only to the skin. Do not take by mouth. Apply evenly and liberally to all exposed areas of the skin 30 minutes before any sun exposure. Reapply sunscreens every 1—2 hours and after swimming, excessive sweating, or towel drying. Follow the directions on the product label.
Sunscreens are not recommended for infants less than 6 months of age. Infants in this age group should be kept out of the sun. Children and infants who are 6 months of age and older should use sunscreens that contain an SPF of 15 or higher. Contact your pediatrician or health care professional regarding the use of this medicine in children.
Use topical insect repellants containing diethyltoluamide, DEET cautiously while using sunscreens. Sunscreens may increase the absorption of diethyltoluamide, DEET into the skin. This is especially important in children.
What if I miss a dose?
What drug(s) may interact with Sunscreens?
• Estrasorb® topical estrogen emulsion
• insect repellants containing diethyltoluamide, DEET
Tell your prescriber or health care professional about all other medicines you are taking, including non-prescription medicines, nutritional supplements, or herbal products. Check with your health care professional before stopping or starting any of your medicines.
What should I watch for while taking Sunscreens?
Minimize your exposure to the sun between the hours of 10 a.m. and 2 p.m. (11 a.m. and 3 p.m. daylight savings time). Be extra careful on cloudy or overcast days and around reflective surfaces such as concrete, sand, snow, or water. You should also wear protective clothing including a hat, long-sleeved shirt, and sunglasses. Avoid sunlamps and tanning beds.
Some sunscreens may discolor and stain light-colored fabrics yellow. Allow sunscreen to dry before covering the area to which the sunscreen was applied.
What side effects may I notice from receiving Sunscreens?
Side effects that you should report to your prescriber or health care professional as soon as possible:
• dark red spots on the skin
• painful, red, pus-filled blisters in hair follicles
Side effects that usually do not require medical attention (report to your prescriber or health care professional if they continue or are bothersome):
• acne
• burning or itching of the skin
• dry or irritated skin
If you experience skin irritation from a sunscreen you can try a different formulation to prevent the reaction from recurring.
Where can I keep my medicine?
Keep out of reach of children.
Store below 40 degrees C (104 degrees F), preferably at room temperature between 15—30 degrees C (59 and 86 degrees F), unless otherwise specified by the manufacturer. Store away from heat and direct light. Replace sunscreens yearly to maintain their effectiveness. Discard after expiration date on the bottle.
Last updated: 6/29/2005 10:52:00 AM
Important Disclaimer: The drug information provided here is for educational purposes only. It is intended to supplement, not substitute for, the diagnosis, treatment and advice of a medical professional. This drug information does not cover all possible uses, precautions, side effects and interactions. It should not be construed to indicate that this or any drug is safe for you. Consult your medical professional for guidance before using any prescription or over the counter drugs.
Gale Encyclopedia of Children's Health:
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Sunscreens
Definition
Sunscreens are products applied to the skin to protect against the harmful effects of the sun's ultraviolet (UV) rays.
Description
Many brands of sunscreens are available, containing a variety of ingredients. The active ingredients work by absorbing, reflecting, or scattering some or all of the sun's rays. Most sunscreen products contain combinations of ingredients. Sunscreen products are sold as lotions, creams, gels, oils, sprays, sticks, and lip balms, and can be bought without a physician's prescription.
The U.S. Food and Drug Administration requires sunscreen products to carry a sun protection factor (SPF) rating on their labels. This number tells how well the sunscreen protects against burning. The higher the number, the longer a person can stay in the sun without burning.
There are three types of ultraviolet light, based on their wavelength: UVA, UVB, and UVC. UVC has the shortest wavelength and is blocked by the earth's ozone layer. Concerns about the depletion of the ozone layer focus on the serious health effects that increased exposure to UVC light would have.
UVB light is the next shortest wavelength and is called the tanning light since it is light in this range that promotes creation of the skin pigment melanin that creates a tan. UVB light only penetrates the outermost layer of the skin, but it promotes basal and squamous cell carcinoma and may worsen the effects of UVA.
Ultraviolet A is long-wave radiation generated by the sun that penetrates more deeply than UVB, causes wrinkling and leathering of the skin and damages connective tissue. UVA is the light that causes melanoma, the most serious skin cancer.
Several types of chemicals are used as sunscreens. They vary by the degree of protection they can provide and the types of ultraviolet light they can block:
- Cinnamates, such as octyl methoxcinnamate, give low levels of protection, and are only effective against UVB light.
- Para-amino benzoic acid (PABA) compounds, including PABA, padimate O (octyl dimethyl PABA), and glyceryl PABA, are effective only against UVB light.
- Salicylates, octylsalicylate, and homosalate offer moderate levels of protection against both UVA and UVB light, but the range of light waves against which they protect is relatively narrow.
- Benzophenones, including oxybenzone and dioxybenzone, protect against a broader range of ultraviolet light than the salicylates and are more useful for broad spectrum protection.
- Physical sunscreens are really sun blockers and include titanium dioxide, red petrolatum, and zinc oxide. Preparations containing these blockers are thick ointments and are usually reserved for skin areas at high risk of burn, such as the nose.
Other compounds, such as Parsol 1789 (avobenzone), Eusolex 8020, and menthyl anthranilate appear to be valuable broad spectrum agents. In one study, the combination of 3 percent butyl methoxydibenzoyl-methane and 7 percent padimate O was the most effective of all sunscreens tested.
In addition to the chemical used as a sunscreen, the vehicle can be important in determining how well a product works. Unfortunately, thick, greasy ointments seem to work better than vanishing creams, lotions, or liquids.
General Use
Users should carefully read the instructions that come with the sunscreen. Some of these products need to be applied as long as one or two hours before sun exposure. Others should be applied 30 minutes before exposure and frequently during exposure.
Users should apply sunscreen liberally to all exposed parts of the skin, including the hands, feet, nose, ears, neck, scalp (if the hair is thin or very short), and eyelids. However, they should avoid getting sunscreen in the eyes, as it can cause irritation. Use a lip balm containing sunscreen to protect the lips. Reapply sunscreen liberally every one or two hours—more frequently when perspiring heavily. People should reapply sunscreen after they go in the water.
Precautions
Sunscreen alone will not provide full protection from the sun. When possible, people should wear a hat, long pants, a long-sleeved shirt, and sunglasses. They should try to stay out of the sun between 10 A.M. and 2 P.M. (11 A.M. to 3 P.M. daylight saving time), when the sun's rays are strongest. The sun can damage the skin even on cloudy days, so people should get in the habit of using a sunscreen every day. They need to be especially careful at high elevations and in areas with surfaces that reflect the sun's rays, such as off sand, water, concrete, and snow.
Sunlamps, tanning beds, and tanning booths were once thought to be safer than the sun, because they give off mainly UVA rays. However, UVA rays are now known to cause serious skin damage and may increase the risk of melanoma. Health experts advise people not to use these tanning devices.
People with fair skin, blond, red, or light brown hair, and light colored eyes are at greatest risk for developing skin cancer. So are people with many large skin moles. These people should avoid exposure to the sun as much as possible. However, even dark skinned people, including African Americans and Hispanic Americans, may suffer skin damage from the sun and should be careful about exposure.
Side Effects
The most common side effects are drying or tightening of the skin. This problem does not need medical attention unless it does not improve. Other side effects are rare, but possible. If any of the following symptoms occur, people should check with a physician as soon as possible:
- acne
- burning, itching, or stinging of the skin
- redness or swelling of the skin
- rash, with or without blisters that ooze and become crusted
- pain in hairy parts of body
- pus in hair follicles
The side effects of sunscreens cannot be prevented but can be minimized by testing a sunscreen on a small area of the body before all-over applications.
Interactions
Anyone who is using a prescription or nonprescription (over-the-counter) drug that is applied to the skin should check with a physician before using a sunscreen.
Parental Concerns
Sunscreens should not be used on children under six months of age because of the risk of side effects. Instead, children this young should be kept out of the sun. Children over six months of age should be protected with clothing and sunscreens of at least SPF 15, preferably lotions. Sunscreens containing alcohol should not be used on children because they may irritate the skin.
Before using a new sunscreen, particularly a newer formulation, it should be tested on a small area of skin. These products have some risk of causing rashes and other side effects.
Sunscreens should always be applied before a trip to the beach or into some other setting with intense sun exposure. Parents who start to apply sunscreen to their children upon arrival at these settings will exceed their own sun exposure limits before they begin to apply sunscreen to themselves.
Parents should consider using two to three different sunscreens at one time, to get the best results with the fewest problems. Liquids may be best for the scalp, since they can penetrate the hair. Lotions may be most appropriate for most of the body. Ointments may be the best choice for the nose and other parts of the face.
Users should always check expiration dates and not use a sunscreen past its expiration. Reapply sunscreens as directed. Children may benefit from a waterproof sunscreen. There have been claims that these sunscreens may cause eye damage, but this appears to be a hoax. There is no basis for this allegation in the medical literature.
Although sunscreen is useful, it is no replacement for subprotective clothing. While a good sunscreen has an SPF of 15 or above, denim fabric has an SPF of 1700. In contrast, a white T-shirt only has an SPF of 15, and, when wet, has an effective SPF of only 10. Sunglasses are also useful for eye protection.
Resources
Periodicals
Chatelain E., B. Gabard, C. Surber. "Skin penetration and sun protection factor of five UV filters: Effect of the vehicle." Skin Pharmacology and Applied Skin Physiology 16, no. 1 (January-February 2003): 28–35.
Web Sites
"Child Care Health Program: Sun Protection for Child Care Providers." Available online at www.metrokc.gov/health/childcare/sunprotection.htm (accessed September 29, 2004).
Emery, David. "Sunscreen Warning Doesn't Hold Water." Available online at
"Sun Screen." Available online at www.keepkidshealthy.com/medicine_cabinet/sun_screens.html (accessed September 29, 2004).
[Article by: Nancy Ross-Flanigan Samuel Uretsky, PharmD]
Gale Encyclopedia of Public Health:
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Sunscreens
Sunscreens can be categorized as chemical sunscreens, physical blockers, or a combination of both. Chemical sunscreens contain UV-absorbing molecules that filter and limit the amount of ultraviolet (UV) radiation exposure at the skin. The most widely used chemical sunscreens in the United States contain para-aminobenzoic acid (PABA) or its derivatives, cinnamates, benzophenones, anthranilates, or salicylates. Some individuals develop allergic contact dermatitis to these compounds in sunscreens. These compounds predominantly absorb short-wave UV light (UVB) although chemicals that contain benzophenones and dibenzoylmethane (Parsol 1789) have also been developed recently to filter long-wave UV light (UVA).
Physical blockers utilize particles that reflect and scatter UV light. The more common physical blockers include titanium dioxide, zinc oxide, magnesium oxide, magnesium silicate (talc), kaolin, iron derivatives, barium sulfate, and red petrolatum. The older, opaque formulations had limited cosmetic appeal; newer blockers, however, have been combined with chemical sunscreens to give a more elegant appearance. In 1978, the Food and Drug Administration classified sunscreens as drugs and thus established standards for toxicity and quality control. The efficacy of sunscreens is measured in terms of the Sun Protection Factor (SPF). The SPF is defined as the ratio of the doses of artificial sunlight required to cause minimal skin redness with and without sunscreen. Individuals who burn easily, who are on photosensitizing medications, or who have light-sensitive diseases should diligently use sunscreens with SPFs between 15 and 30. Reapplication after prolonged sweating or swimming is recommended. Although sunscreens can provide protection against sunburns, its role in skin cancer protection remains a controversial issue. Some, but not all, studies have found an increased risk of cutaneous melanoma with sunscreen use. The most likely explanation is the individuals who use sunscreen tend to stay out longer in the sun, thereby increasing photocarcinogenesis.
(SEE ALSO: Food and Drug Administration: Skin Cancer; Ultraviolet Radiation)
— HENSIN TSAO
Saunders Veterinary Dictionary:
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sunscreen
A topical agent that filters ultraviolet rays reaching the skin; used to prevent sunburn, actinic dermatitis, and in the control of discoid lupus erythematosus.
Random House Word Menu:
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categories related to 'sunscreen'
- Grooming Aids and Processes - sunscreen: chemical lotion for preventing or retarding sunburn
Wikipedia on Answers.com:
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Sunscreen
For suntan lotion that intensifies sun exposure, see Indoor tanning lotion . For the electronic music group, see Sunblock (band) . For the song, see Wear Sunscreen.
Sunscreen (also commonly known as sunblock, sun tan lotion, sun screen, sun cream or block out)[1] is a lotion, spray, gel or other topical product that absorbs or reflects some of the sun's ultraviolet (UV) radiation on the skin exposed to sunlight and thus helps protect against sunburn. Skin-lightening products have sunscreen to protect lightened skin because light skin is more susceptible to sun damage than darker skin. A number of sunscreens have tanning powder to help the skin to darken or tan, however tanning powder does not provide protection from UV rays.
Sunscreens contain one or more of the following ingredients:
- Organic chemical compounds that absorb ultraviolet light.
- Inorganic particulates that reflect, scatter, and absorb UV light (such as titanium dioxide, zinc oxide, or a combination of both).
- Organic particulates that mostly absorb light like organic chemical compounds, but contain multiple chromophores, may reflect and scatter a fraction of light like inorganic particulates, and behave differently in formulations than organic chemical compounds. An example is Tinosorb M. Since the UV-attenuating efficacy depends strongly on particle size, the material is micronised to particle sizes below 200 nm. The mode of action of this photostable filter system is governed to about 90% by absorption and 10% by scattering of UV light.
Depending on the mode of action sunscreens can be classified into physical sunscreens (i.e., those that reflect the sunlight) or chemical sunscreens (i.e., those that absorb the UV light).[2]
Medical organizations such as the American Cancer Society recommend the use of sunscreen because it prevents the squamous cell carcinoma and the basal cell carcinoma.[3] However, the use of sunscreens is controversial for various reasons. Many sunscreens do not block UVA radiation, which does not cause sunburn but can increase the rate of melanoma, another kind of skin cancer, and photodermatitis, so people using sunscreens may be exposed to high UVA levels without realizing it. [4] The use of broad-spectrum (UVA/UVB) sunscreens can address this concern.
Although sunscreen is sometimes called "suntan lotion", the latter is different in that it is used to intensify UV rays whereas the former is used to block UV rays.
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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 is still today a marketer of sunscreen products.[5] It has been estimated that Gletscher Crème had a sun protection factor of 2.
The first widely used sunscreen was produced by Benjamin Green, 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. Sales of this product boomed when Coppertone acquired the patent and marketed the substance under the Coppertone girl and Bain de Soleil branding in the early 1950s.
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.
Newer sunscreens have been developed with the ability to better withstand contact with water, heat and sweat.
Measurements of sunscreen protection
Sun protection factor (SPF) and labeling requirements
The sun protection factor 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).[2]
The SPF is the amount of UV radiation required to cause sunburn on skin with the sunscreen on, as a multiple of the amount required without the sunscreen.[6] There is a popular oversimplification of how SPF determines how long one can stay in the sun. For example, many users believe that, if they normally get sunburn in one hour, then an SPF 15 sunscreen allows them to stay in the sun fifteen hours (i.e. fifteen times longer) without getting sunburn. This would be true if the intensity of UV radiation were the same for the whole fifteen hours as in the one hour, but this is not normally the case. Intensity of solar radiation varies considerably with time of day. During early morning and late afternoon, the sun's radiation intensity is diminished since it must pass through more of the Earth's atmosphere while it is near the horizon.
In practice, the protection from a particular sunscreen depends, besides on SPF, 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 are also caused by ultraviolet type A (UVA, wavelength 320 to 400 nm), which does not cause reddening or pain. Conventional sunscreen blocks very little UVA radiation relative to the nominal SPF; broad-spectrum sunscreens are designed to protect against both UVB and UVA.[7][8][9] According to a 2004 study, UVA also causes DNA damage to cells deep within the skin, increasing the risk of malignant melanomas.[10] Even some products labeled "broad-spectrum UVA/UVB protection" do not provide good protection against UVA rays.[11] The best UVA protection is provided by products that contain zinc oxide, avobenzone, and ecamsule[citation needed]. Titanium dioxide probably gives good protection, but does not completely cover the entire UV-A spectrum, as recent research suggests that zinc oxide is superior to titanium dioxide at wavelengths between 340 and 380 nm.[12]
Owing to consumer confusion over the real degree and duration of protection offered, labeling restrictions are in force in several countries. In the EU sunscreen labels can only go up to SPF 50+ (actually indicating a SPF of 60 or higher)[13] while Australia's upper limit is 30+.[14] In the 2007 and 2011 draft rules, the Food and Drug Administration (FDA) proposed a maximum SPF label of 50, to limit unrealistic claims.[15][16]
Others have proposed restricting the active ingredients to an SPF of no more than 50, due to lack of evidence that higher dosages provide more meaningful protection (especially due to the logarithmic nature of the scale).[17]
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 (290–320 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.[18] Numerous methods have been devised for evaluation of UVA and UVB protection. The most reliable spectrophotochemical methods eliminate the subjective nature of grading erythema.[19]
Mathematically, the SPF is calculated from measured data as
where 
is the solar irradiance spectrum, 
the erythemal action spectrum, and 
the monochromatic protection factor, all functions of the wavelength 
. 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)
The persistent pigment darkening (PPD) method is a method of measuring UVA protection, similar to the SPF method of measuring UVB light protection. Originally developed in Japan, it is the preferred method used by manufacturers such as L'Oréal.
Instead of measuring erythema or reddening of the skin, the PPD method uses UVA radiation to cause a persistent darkening or tanning of the skin. Theoretically, a sunscreen with a PPD rating of 10 should allow a person 10 times as much UVA exposure as would be without protection. The PPD method is an in vivo test like SPF. In addition, Colipa has introduced a method that, it is claimed, can measure this in vitro and provide parity with the PPD method.[20]
SPF equivalence
As part of revised guidelines for sunscreens in the EU, there is a requirement to provide the consumer with a minimum level of UVA protection in relation to the SPF. This should be a UVA PF of at least 1/3 of the SPF to carry the UVA seal. The implementation of this seal is in its phase-in period,[when?] so a sunscreen without it may already offer this protection.[21]
A set of final U.S. FDA rules going into effect for summer 2012 defines the phrase "broad spectrum" as having a UVA SPF at least as high as the UVB SPF.[16]
Star rating system
In the UK and Ireland, the Boots star rating system is a proprietary in vitro method used to describe the ratio of UVA to UVB protection offered by sunscreen creams and sprays. Based on original work by Prof. Brian Diffey at Newcastle University, the Boots Company in Nottingham, UK, developed a standard method that has been adopted by most companies marketing these products in the UK. The logo and methodology of the test are licenced for a token fee to any manufacturer or brand of sunscreens that are sold in the Boots retail chain, provided the products to which the logo is applied perform to the standard claimed. Own Label products exclusively sold in other retailers are now excluded from the terms of the licence. 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 best. The method has recently been revised in the light of the Colipa UVA PF test, and with the new EU recommendations regarding UVA PF. The method still uses a spectrophotometer to measure absorption of UVA vs UVB; the difference stems from a requirement to pre-irradiate samples (where this was not previously required) to give a better indication of UVA protection, and of photostability when the product is used. With the current methodology, the lowest rating is three stars, the highest being five stars. In August 2007, the FDA put out for consultation the proposal that a version of this protocol be used to inform users of American product of the protection that it gives against UVA,[22] but after concern this would be too confusing this was not adopted.[17]
PA system
Asian brands, particularly Japanese ones, tend to use the PA system to measure how light the cream is when you apply it to the skin. There are four levels: PA. PA+, PA++ and PA+++.
Sunblock is a type of sunscreen
Sunblock typically refers to opaque sunscreen that is effective at blocking both UVA and UVB rays and uses a heavy carrier oil to resist being washed off. Titanium dioxide and zinc oxide are two of the important ingredients in sunblock. Unlike the organic sun-blocking agents used in many sunscreens, these metal oxides do not degrade with exposure to sunlight.
The use of the word "sunblock" in the marketing of sunscreens is controversial. The FDA has considered banning such use because it can lead consumers to overestimate the effectiveness of products so labeled.[23]
For total protection against damage from the sun, the skin needs to be protected from UVA, UVB and IRA (infrared light). Roughly 35% of solar energy is IRA.[24]
Potential health risks
Main article: Sunscreen controversy
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As a defense against UV radiation, the amount of the brown pigment melanin in the skin increases when exposed to moderate (depending on skin type) levels of radiation; this is commonly known as a sun tan. The purpose of melanin is to absorb UV radiation and dissipate the energy as harmless heat, blocking the UV from damaging skin tissue. UVA gives a quick tan that lasts for days by oxidizing melanin that was already present and triggers the release of the melanin from melanocytes. UVB on the other hand yields a tan that takes roughly two days to develop because it stimulates the body to produce more melanin. The photochemical properties of melanin make it an excellent photoprotectant.
Sunscreen chemicals, on the other hand, cannot dissipate the energy of the excited state as efficiently as melanin and therefore the penetration of sunscreen ingredients into the lower layers of the skin increases the amount of free radicals and reactive oxygen species (ROS).[25]
Some sunscreen lotions now include compounds such as titanium dioxide and zinc oxide, inert fillers which helps protect against UV rays via light scattering and physically blocking the light pathway into the dermal layers. Other UVA blocking compounds found in sunscreen include Avobenzone. There are also naturally occurring compounds found in rainforest plants that have been known to protect the skin from UV radiation damage, such as the fern Phlebodium aureum.
Some sunscreen chemicals produce potentially harmful substances if they are illuminated while in contact with living cells.[26][27][28] The amount of sunscreen that penetrates through the stratum corneum may be large enough to cause damage. In one study of sunscreens, the authors write:
The question whether UV filters acts on or in the skin has so far not been fully answered. Despite the fact that an answer would be a key to improve formulations of sun protection products, many publications carefully avoid addressing this question.[29]
In an experiment by Hanson et al. that was published in 2006, the amount of harmful reactive oxygen species was measured in untreated and in sunscreen-treated skin. In the first 20 minutes the film of sunscreen had a protective effect and the number of ROS species was smaller. After 60 minutes, however, the amount of absorbed sunscreen was so high that the amount of ROS was higher in the sunscreen-treated skin than in the untreated skin.[25]
George Zachariadis and E Sahanidou of the Laboratory of Analytical Chemistry, at Aristotle University, in Thessaloniki, Greece, have now carried out an ICP-AES analysis of several commercially available sunscreen creams and lotions. "The objective was the simultaneous determination of titanium and several minor, trace or toxic elements (aluminum, zinc, magnesium, iron, manganese, copper, chromium, lead, and bismuth) in the final products," the researchers say. They concluded that "Most of the commercial preparations that were studied showed generally good agreement to the ingredients listed on the product label." However, they also point out that the quantitative composition of the products tested cannot be assessed because the product labels usually do not provide a detailed break down of all ingredients and their concentrations. They also point out that, worryingly, their tests consistently revealed the presence of elements not cited in the product formulation, which emphasized the need for a standardized and official testing method for multi-element quality control of these products.[30]
Some epidemiological studies indicate an increased risk of malignant melanoma for the sunscreen user.[31][32][33][34][35][36][37][38] Despite these studies, no medical association has published recommendations to not use sunblock. Different meta-analysis publications have concluded that the evidence is not yet sufficient to claim a positive correlation between sunscreen use and malignant melanoma.[39][40]
Adverse health effects may be associated with some synthetic compounds in sunscreens.[41] In 2007 two studies by the CDC highlighted concerns about the sunscreen chemical oxybenzone (benzophenone-3). They first detected the chemicals in greater than 95% of 2000 Americans tested, while the second found that mothers with high levels of oxybenzone in their bodies were more likely to give birth to underweight baby girls.[42]
Concerns have been raised regarding the use of nanoparticles in sunscreen.[43] Theoretically, sunscreen nanoparticles could increase rates of certain cancers, or diseases similar to those caused by asbestos.[44] In 2006 the Therapeutic Goods Administration of Australia concluded a study and found:
"There is evidence from isolated cell experiments that zinc oxide and titanium dioxide can induce free radical formation in the presence of light and that this may damage these cells (photo-mutagenicity with zinc oxide). However, this would only be of concern in people using sunscreens if the zinc oxide and titanium dioxide penetrated into viable skin cells. The weight of current evidence is that they remain on the surface of the skin and in the outer dead layer (stratum corneum) of the skin." [43]
Vitamin D
Artificial sunscreen absorbs ultraviolet light and prevents it from reaching the skin. It has been reported that sunscreen with a sun protection factor (SPF) of 8 based on the UVB spectrum can decrease vitamin D synthetic capacity by 95 percent, whereas sunscreen with an SPF of 15 can reduce synthetic capacity by 98 percent (Matsuoka et al., 1987).[45] Natural sunscreen has been proved to improve pigmentation from sun tanning.
This was leading to deficiency in Australia after a government campaign to increase sunscreen use.[46] Doctors recommend spending small amounts of time in the sun without sun protection to ensure adequate production of vitamin D.[47] When the UV index is greater than 3 (which occurs daily within the tropics and daily during the spring and summer seasons in temperate regions) adequate amounts of vitamin D3 can be made in the skin after only ten to fifteen minutes of sun exposure at least two times per week to the face, arms, hands, or back without sunscreen. With longer exposure to UVB rays, an equilibrium is achieved in the skin, and the vitamin simply degrades as fast as it is generated.[48]
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 photodegradation.[49] A chemical stabilizer is included in some sunscreens containing avobenzone to slow its breakdown - examples include formulations containing Helioplex[50] and AvoTriplex.[51] The stability of avobenzone can also be improved by bemotrizinol,[52] octocrylene[53] and various other photostabilisers.
FDA allowable ingredients
The following are the FDA allowable active ingredients in sunscreens:
| UV-filter | Other names | Maximum concentration | Permitted in these countries | Results of safety testing |
|---|---|---|---|---|
| p-Aminobenzoic acid | PABA | 15% (EC- banned from sale to consumers from 8 October 2009) | USA, AUS | Protects against skin tumors in mice.[54][55][56] Shown to increase DNA defects, however, and is now less commonly used. |
| Padimate O | OD-PABA, octyldimethyl-PABA, σ-PABA | 8% (EC,USA,AUS) 10% (JP)
(Not currently supported in EU and may be delisted) |
EC, USA, AUS, JP | Not tested |
| Phenylbenzimidazole sulfonic acid | Ensulizole, Eusolex 232, PBSA, Parsol HS | 4% (US,AUS) 8% (EC) 3% (JP) | EC,USA, AUS, JP | Genotoxic in bacteria[57] |
| Cinoxate | 2-Ethoxyethyl p-methoxycinnamate | 3% (US) 6% (AUS) | USA, AUS | Not tested |
| Dioxybenzone | Benzophenone-8 | 3% | USA, AUS | Not tested |
| Oxybenzone | Benzophenone-3, Eusolex 4360, Escalol 567 | 6% (US) 10% (AUS,EU) 5% (JP) | EC, USA, AUS, JP | Not tested |
| Homosalate | Homomethyl salicylate, HMS | 10% (EC, JP) 15% (US,AUS) | EC, USA, AUS, JP | Not tested |
| Menthyl anthranilate | Meradimate | 5% | USA, AUS | Not tested |
| Octocrylene | Eusolex OCR, 2-cyano-3,3diphenyl acrylic acid, 2-ethylhexylester | 10% | EC,USA, AUS, JP | Increases ROS[25] |
| Octyl methoxycinnamate | Octinoxate, EMC, OMC, Ethylmethoxycinnamate, Escalol 557, 2-ethylhexyl-paramethoxycinnamate, Parsol MCX | 7.5% (US) 10% (EC,AUS)20% (JP) | EC,USA, AUS, JP | |
| Octyl salicylate | Octisalate, 2-Ethylhexyl salicylate, Escalol 587, | 5% (EC,USA,AUS) 10% (JP) | EC,USA, AUS, JP | Not tested |
| Sulisobenzone | 2-Hydroxy-4-Methoxybenzophenone-5-sulfonic acid,
3-benzoyl-4-hydroxy-6-methoxybenzenesulfonic acid, Benzophenone-4, Escalol 577 |
5% (EC) 10% (US, AUS, JP) | EC,USA, AUS, JP | |
| Trolamine salicylate | Triethanolamine salicylate | 12% | USA, AUS | Not tested |
| Avobenzone | 1-(4-methoxyphenyl)-3-(4-tert-butyl phenyl)propane-1,3-dione, Butyl methoxy dibenzoylmethane, BMDBM, Parsol 1789, Eusolex 9020 |
3% (US) 5% (EC,AUS)10% (JP) | EC, USA, AUS, JP | Not available[58] |
| Ecamsule | Mexoryl SX, Terephthalylidene Dicamphor Sulfonic Acid | 10% | EC,AUS (US:Approved in certain formulations up to 3% via New Drug Application (NDA) Route) | Protects against skin tumors in mice[59][60][61] |
| Titanium dioxide | CI77891 | 25% (No limit Japan) | EC,USA, AUS, JP | Not tested |
| Zinc oxide | 25% (US) 20% (AUS)
(EC-25% provided particle size >100 nm) (Japan, No Limit) |
EC,USA, AUS, JP | Protects against skin tumors in mice[59] |
Other ingredients approved within the EU[62] and other parts of the world,[63] that have not been included in the current FDA Monograph:
| UV-filter | Other names | Maximum concentration | Permitted in |
|---|---|---|---|
| 4-Methylbenzylidene camphor | Enzacamene, Parsol 5000, Eusolex 6300, MBC | 4%* | EC, AUS |
| Tinosorb M | Bisoctrizole, Methylene Bis-Benzotriazolyl Tetramethylbutylphenol, MBBT | 10%* | EC, AUS, JP |
| Tinosorb S | Bis-ethylhexyloxyphenol methoxyphenol triazine, Bemotrizinol, BEMT, anisotriazine | 10% (EC, AUS) 3% (JP)* | EC, AUS, JP |
| Neo Heliopan AP | Bisdisulizole Disodium, Disodium phenyl dibenzimidazole tetrasulfonate, bisimidazylate, DPDT | 10% | EC, AUS |
| Mexoryl XL | Drometrizole Trisiloxane | 15% | EC, AUS |
| Benzophenone-9 | Uvinul DS 49, CAS 3121-60-6, Sodium Dihydroxy Dimethoxy Disulfobenzophenone [64] | 10% | JP |
| Uvinul T 150 | Octyl triazone, ethylhexyl triazone, EHT | 5% (EC, AUS) 3% (JP)* | EC, AUS |
| Uvinul A Plus | Diethylamino Hydroxybenzoyl Hexyl Benzoate | 10% (EC,JP) | EC, JP |
| Uvasorb HEB | Iscotrizinol, Diethylhexyl butamido triazone, DBT | 10% (EC) 5% (JP) * | EC, JP |
| Parsol SLX | Dimethico-diethylbenzalmalonate, Polysilicone-15 | 10% | EC, AUS, JP |
| Isopentenyl-4-methoxycinnamate | Isoamyl p-Methoxycinnamate, IMC, Neo Heliopan E1000, Amiloxate | 10% * | EC, AUS |
Many of the ingredients not approved by the FDA are relatively new and developed to absorb UVA.[65]
* Time and Extent Application (TEA), Proposed Rule on FDA approval expected 2009
Application
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This section contains instructions, advice, or how-to content. The purpose of Wikipedia is to present facts, not to train. Please help improve this article either by rewriting the how-to content or by moving it to Wikiversity or Wikibooks. (October 2009) |
Excessive exposure to direct sunlight is potentially harmful. Excessive exposure can result in sunburn if a person does not wear sun protective clothing or use suitable sunscreen. Products with a higher SPF (Sun Protection Factor) level provide greater protection against ultraviolet 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. A sunscreen should also be hypoallergenic and noncomedogenic so it does not cause a rash or clog the pores, which can cause acne.
For those choosing to tan, some dermatologists recommend the following preventative measures:
- Sunscreens should block both UVA and UVB rays. These are called broad-spectrum sunscreens, which should also be hypoallergenic and noncomedogenic so they do not cause a rash or clog the pores, which can cause acne.
- Sunscreens need to be applied thickly enough to get the full SPF protection.
- Sunscreens should be applied 15 to 30 minutes before exposure, followed by one reapplication 15 to 30 minutes after the sun exposure begins. Further reapplication is necessary only after activities such as swimming, sweating, and rubbing.[66]
- Sun rays are strongest between 10 am and 4 pm.[67] Sun rays are stronger at higher elevations (mountains) and latitudes near the equator.
- Wearing a hat with a brim and anti-UV sunglasses can provide almost 100% protection against ultraviolet radiation's entering the eyes.
- Reflective surfaces like snow and water can greatly increase the amount of UV radiation to which the skin is exposed.
Recent evidence indicates that caffeine and caffeine sodium benzoate increase UVB-induced apoptosis both in topical and oral applications. In mice, UVB-induced hyperplasia was greatly reduced with administration of these substances. Although studies in humans remain untested, caffeine and caffeine sodium benzoate may be novel inhibitors of skin cancer.[68]
Dosage
The dose used in FDA sunscreen testing is 2.2 mg/cm² of exposed skin.[49] 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. Larger individuals should scale these quantities accordingly.
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, or rubbing/wiping.[69]
More recent research at the University of California, Riverside, indicates that sunscreen must 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 that were absorbed into the skin.[25] Some studies have shown that people commonly apply only 1/2 to 1/4 of the amount recommended to achieve the rated sun protection factor (SPF), and in consequence the effective SPF should be downgraded to a square or 4th root of the advertised value.[70] A later study found a significant exponential relation between SPF and the amount of sunscreen applied and the results are closer to the linearity than expected by theory.[71]
Label regulations
Updated package labeling standards in the United States have been under development since 1978.
A set of final FDA rules going into effect for summer 2012 bans "waterproof" claims instead requiring claims of 40 or 80 minutes "water-resistant" protection. It also required a standardized "Drug Facts" label and requires specific FDA approval for "sunblock" and "instant protection" labels. Claims of protection over 2 hours are not allowed without specific approval.[16]
See also
Notes
- ^ "Preventing melanoma". Cancer Research UK. http://www.cancerhelp.org.uk/help/default.asp?page=3007. Retrieved 2009-09-22.
- ^ a b Sunscreens | The Ageing Skin
- ^ What You Need To Know About Skin Cancer
- ^ {{cite journal | author=Terence SC Poon, Ross StC Barnetson and Gary M Halliday | title= Prevention of Immunosuppression by Sunscreens in Humans Is Unrelated to Protection from Erythema and Dependent on Protection from Ultraviolet A in the Face of Constant Ultraviolet B Protection | journal= J Invest Dermatol | volume=121 | pages=184-90 | year=2003 | (2003) 121, 184–190.
- ^ 70 years since the PIZ BUIN mountain inspired a man to invent the world's first sun protection cream
- ^ "Sunburn Protection Factor (SPF)". Food and Drug Administration (United States). 2009-04-30. http://www.fda.gov/AboutFDA/CentersOffices/CDER/ucm106351.htm. Retrieved 2009-09-25.
- ^ Stege, H.; Budde; Grether-Beck; Richard; Rougier; Ruzicka; Krutmann (2002). "Sunscreens with high SPF values are not equivalent in protection from UVA induced polymorphous light eruption". European journal of dermatology : EJD 12 (4): IV–VI. PMID 12118426.
- ^ Haywood, R.; Wardman, P.; Sanders, R.; Linge, C. (2003). "Sunscreens inadequately protect against ultraviolet-A-induced free radicals in skin: implications for skin aging and melanoma?". The Journal of investigative dermatology 121 (4): 862–868. DOI:10.1046/j.1523-1747.2003.12498.x. PMID 14632206.
- ^ Moyal, D.; Fourtanier, A. (2008). "Broad-spectrum sunscreens provide better protection from solar ultraviolet-simulated radiation and natural sunlight-induced immunosuppression in human beings". Journal of the American Academy of Dermatology 58 (5 Suppl 2): S149–S154. DOI:10.1016/j.jaad.2007.04.035. PMID 18410801.
- ^ Berneburg M, Plettenberg H, Medve-König K, Pfahlberg A, Gers-Barlag H, Gefeller O, Krutmann J (2004). "Induction of the photoaging-associated mitochondrial common deletion in vivo in normal human skin". J Invest Dermatol 122 (5): 1277–83. DOI:10.1111/j.0022-202X.2004.22502.x. PMID 15140232.
- ^ MSNBC.com : Sunscreen — protection or 'snake oil?'
- ^ Pinnell SR, Fairhurst D, Gillies R, Mitchnick MA, Kollias N (April 2000). "Microfine zinc oxide is a superior sunscreen ingredient to microfine titanium dioxide". Dermatol Surg 26 (4): 309–14. DOI:10.1046/j.1524-4725.2000.99237.x. PMID 10759815. http://www.blackwell-synergy.com/openurl?genre=article&sid=nlm:pubmed&issn=1076-0512&date=2000&volume=26&issue=4&spage=309.
- ^ Commission Recommendation of 22 September 2006 on the efficacy of sunscreen products and the claims made relating thereto. Official Journal of the European Union. 2006-09-22. http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=CELEX:32006H0647:EN:NOT. Retrieved 2009-09-25.
- ^ "UV Resource Guide - Sunscreens". Arpansa. 2008-12-20. http://www.arpansa.gov.au/uvrg/rginfo_p13.cfm. Retrieved 2009-09-25.
- ^ Questions and Answers on the 2007 Sunscreen Proposed Rule
- ^ a b c "Questions and Answers: FDA announces new requirements for over-the-counter (OTC) sunscreen products marketed in the U.S.". 2011-06-23. http://www.fda.gov/Drugs/ResourcesForYou/Consumers/BuyingUsingMedicineSafely/UnderstandingOver-the-CounterMedicines/ucm258468.htm. Retrieved 2012-04-10.
- ^ a b "Sunscreen Takes Some Heat: New Dangers, New Rules". 2011-06-16. http://onpoint.wbur.org/2011/06/16/sunscreen. Retrieved 2012-04-10.
- ^ Optometrics products
- ^ Dominique Moyal "How to measure UVA protection afforded by suncreen products" www.medscape.com/viewarticle/576849
- ^ Colipa UVA method
- ^ www.colipa.com[dead link]
- ^ [1] Questions and Answers on the 2007 Sunscreen Proposed Rule
- ^ http://www.ewg.org/2010sunscreen/faqs-2010/#28
- ^ P. Schroeder, PhD and J. Krutmann, MD What is Needed for a Sunscreen to Provide Complete Protection
- ^ a b c d Hanson, KM; Gratton, E; Bardeen, CJ (2006). "Sunscreen enhancement of UV-induced reactive oxygen species in the skin". Free Radical Biology and Medicine 41 (8): 1205–12. DOI:10.1016/j.freeradbiomed.2006.06.011. PMID 17015167.
- ^ Xu, C; Green, Adele; Parisi, Alfio; Parsons, Peter G (2001). "Photosensitization of the Sunscreen Octyl p-Dimethylaminobenzoate b UVA in Human Melanocytes but not in Keratinocytes". Photochemistry and Photobiology 73 (6): 600–604. DOI:10.1562/0031-8655(2001)073<0600:POTSOP>2.0.CO;2. PMID 11421064.
- ^ Knowland, John; McKenzie, Edward A; McHugh, Peter J; Cridland, Nigel A (1993). "Sunlight-induced mutagenicity of a common sunscreen ingredient". FEBS Letters 324 (3): 309–313. DOI:10.1016/0014-5793(93)80141-G. PMID 8405372.
- ^ Damiani, E; Greci, L; Parsons, R; Knowland, (1999). "Nitroxide radicals protect DNA from damage when illuminated in vitro in the presence of dibenzoylmethane and a common sunscreen ingredient". Free Radic. Biol. Med. 26 (7–8): 809–816. DOI:10.1016/S0891-5849(98)00292-5. PMID 10232823.
- ^ Chatelaine, E.; Gabard, B.; Surber, C. (2003). "Skin penetration and sun protection factor of five UV filters: Effect of the vehicle". Skin Pharmacol. Appl. Skin Physiol 16 (1): 28–35. DOI:10.1159/000068291. PMID 12566826. http://content.karger.com/ProdukteDB/produkte.asp?Aktion=ShowPDF&ArtikelNr=68291&ProduktNr=224219&Ausgabe=228903&filename=68291.pdf.
- ^ David Bradley (August 15). "Toxic sunscreen testing". Http://www.spectroscopynow.com/coi/cda/detail.cda?id=22103&type=Feature&chId=1&page=1 year=2009.
- ^ Garland C, Garland F, Gorham E (04/01/1992). "Could sunscreens increase melanoma risk?". Am J Public Health 82 (4): 614–5. DOI:10.2105/AJPH.82.4.614. PMC 1694089. PMID 1546792. http://www.ajph.org/cgi/reprint/82/4/614.
- ^ Westerdahl, J.; Ingvar, C.; Masback, A.; Olsson, H. (2000). "Sunscreen use and malignant melanoma". International Journal of Cancer. Journal International Du Cancer 87 (1): 145–50. DOI:10.1002/1097-0215(20000701)87:1<145::AID-IJC22>3.0.CO;2-3. PMID 10861466.
- ^ Autier, P.; Dore, J. F.; Schifflers, E.; Al, et; Bollaerts, A; Koelmel, KF; Gefeller, O; Liabeuf, A et al. (1995). "Melanoma and use of sunscreens: An EORTC case control study in Germany, Belgium and France". Int. J. Cancer 61 (6): 749–755. DOI:10.1002/ijc.2910610602. PMID 7790106.
- ^ Weinstock, M. A. (1999). "Do sunscreens increase or decrease melanoma risk: An epidemiologic evaluation". Journal of Investigative Dermatology Symposium Proceedings 4 (1): 97–100. PMID 10537017.
- ^ Vainio, H., Bianchini, F. (2000). "Cancer-preventive effects of sunscreens are uncertain". Scandinavian Journal of Work Environment and Health 26: 529–31.
- ^ Wolf P, Quehenberger F, Müllegger R, Stranz B, Kerl H. (1998). "Phenotypic markers, sunlight-related factors and sunscreen use in patients with cutaneous melanoma: an Austrian case-control study". Melanoma Res. 8 (4): 370–378. DOI:10.1097/00008390-199808000-00012. PMID 9764814.
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External links
- FDA rulemaking history for sunscreens
- Make sure your sunscreen has The Skin Cancer Foundation's Seal of Recommendation
- Environmental Working Group: July 2009 Sunscreen Safety Guide and Report
- Information on what sunscreens are and how they work from The Skin Cancer Foundation
- 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
- European Cosmetics ingredient database (CosIng)
- How does sunscreen work? Simple explanation from physics.org
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Translations:
Top
Sunscreen
Nederlands (Dutch)
zonnescherm, zonnebrandcrème
Français (French)
n. - écran soleil
Deutsch (German)
n. - Sonnencreme
Ελληνική (Greek)
n. - αντηλιακή κρέμα
Italiano (Italian)
crema per il sole
Português (Portuguese)
n. - filtro solar (m)
Русский (Russian)
солнцезащитный козырек (на автомобиле), крем или лосьон от загара
Español (Spanish)
n. - protección solar
Svenska (Swedish)
n. - solskyddsmedel
中文（简体）(Chinese (Simplified))
防晒油
中文（繁體）(Chinese (Traditional))
n. - 防曬油
日本語 (Japanese)
n. - 日焼け止め, 日焼け止め剤
العربيه (Arabic)
(الاسم) كريم للوقايه من الشمس
עברית (Hebrew)
n. - קרם או תמסיך הגנה מפני השמש, מסך/וילון להגנה מאור השמש
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