The Skin Cancer Foundation's Guide to Sunscreens

Our exhaustive Q & A with Henry W. Lim, MD, and Steven Q. Wang, MD, two key members of the Foundation’s Photobiology Committee (experts on sun damage and sun protection) answers the most commonly asked questions about sunscreens.

Q. Why are sunscreens important for our well-being?

A. There is a dark side to the sun. The US government has officially identified ultraviolet radiation (UVR) both from the sun and from tanning machines as a known cause of cancer in humans. UVR produces DNA damage that may lead to mutations (abnormalities) in genes involved in the development of skin cancer. Therefore, along with other sun safety strategies, sunscreens that absorb or block UVR serve an important protective function. 

The US Environmental Protection Agency (EPA) estimates that the sun causes 90 percent of all nonmelanoma skin cancers,1 and other research links it to 65 percent of all melanomas.2 Each year, an estimated 3.5 million or more new cases occur in the US of the nonmelanoma skin cancers basal and squamous cell carcinoma (BCC and SCC).3 An estimated 76,250 new cases of invasive melanoma, the most dangerous form of skin cancer, will be diagnosed in the US in 2012, with nearly 9,180 resulting in death, according to the American Cancer Society.4 

Photoaging, or UV-induced skin aging, is another long-term result of sun exposure. While not threatening to life, it is threatening to quality of life. Excessive unprotected time in the sun leads to premature wrinkling, sagging, a leathery texture and hyperpigmentation (so-called “aging spots” or “liver spots” that are really the result of sun damage).

Sunburn, the most immediate, obvious example of UVR damage, results from sun-induced inflammation and/or blistering of the skin. When immune cells called mast cells race to the injured skin site in response to the damage, they dilate the blood vessels and produce erythema (reddening), edema (swelling), and burning and stinging sensations as part of the healing process. This DNA damage can be the first step towards skin cancer. Intermittent, intense UVR exposure, often producing sunburn, is believed to be more closely associated with melanoma than is chronic sun exposure. One blistering sunburn in childhood or adolescence doubles the risk of melanoma later in life; five sunburns by any age doubles the risk as well.5 

UVR also weakens immune surveillance mechanisms, allowing tumor cells to proliferate more freely. This effect adds to the immune suppression induced by other causes, including cancer chemotherapy and antirejection drugs for transplants.5 Sunscreen is one vital tool that can help prevent all of these UVR-induced assaults on the body as part of a comprehensive photoprotection program, along with sun avoidance or use of shade during peak sunlight hours (10 AM to 4 PM), and protective clothing, including a wide-brimmed hat and UVR-blocking sunglasses. 

Q.What are the major risk factors for skin cancer?

A. Heredity has a major role; entire families can be melanoma-prone. In general, fair-skinned individuals, skin types I and II, living between 0º and 45º north or south latitudes (the hottest, most equatorial zones), are at highest risk for skin cancer. They generally have blond or red hair, blue or hazel eyes, burn easily and tan minimally or not at all. People with many moles or any large, atypical moles are also at higher risk. 

Finally, both intermittent, intense exposure (the kind you get on vacation on a sunny isle, often leading to sunburn) and chronic lifetime exposure add to skin cancer risk. Studies have shown that chronic sun exposure is most associated with the development of squamous cell carcinoma, the second most common skin cancer, while both chronic and intense, intermittent exposure are believed to play a role in basal cell carcinoma,7,8 the most common skin cancer. 

Q. Should sunscreen be used only by people at high risk?

A. Although people with dark skin are not as high-risk as those with light skin, they develop skin cancer too and should use sunscreen. Dyspigmentation (abnormal increase or decrease in the production or distribution of pigment in the skin) is also a major concern for many dark-skinned individuals, and can be minimized by photoprotection, including regular sunscreen use. For adequate protection against melanoma, nonmelanoma skin cancers and photoaging, everyone over the age of six months should use sunscreen daily year-round, in any weather. (Infants should be kept out of the sun or protected with clothing and an umbrella or stroller hood.) 

Sunscreen should not be neglected on overcast days, as 70-80 percent of the sun's rays – above all, long-spectrum UVA rays – go through clouds and fog. In addition, according to the World Health Organization, UVR levels rise by about 4 to 5 percent for every 1000 feet of altitude, and reflection from sand, water, snow or concrete magnifies their effects by up to 80 percent.

Q. How does photosensitivity add to the risk?

A. Phototoxicity can result when a person uses one or another of a wide range of photosensitizing products and then is exposed to UVR. Typically, hours after the exposure, the initial reaction, resembling a severe sunburn, appears. Many of the sensitizing agents are drugs, such as the antibiotics tetracycline, doxycycline and ciprofloxacin; the nonsteroidal anti-inflammatory ibuprofen; and the diuretic furosemide, as well as retinoids. Photoallergy, like other allergies, occurs in previously sensitized individuals. Repeat exposure to the same allergen plus UVR exposure prompts a typical pruritic (intense itching) and eczematous reaction. In some individuals, even certain sunscreen ingredients cause photoallergy; these people should switch sunscreens. [See Table 1.] 

Anyone with a known history of photosensitivity should stay out of the sun as much as possible and rigorously use sunscreen and other sun-protective measures. Photoprotection is also advised for patients with photo-aggravated diseases such as lupus erythematosus or dermatomyositis. 






(minocycline, doxycycline, tetracycline)

(ciprofloxacin, ofloxacin, norfloxacin)

















Coal Tar


5-aminolevulinic acid


PABA and derivatives





Musk ambrette



Table 1. Common Photosensitizing Medications and Chemicals
Courtesy of Craig A. Elmets, MD, and Alexandra Zhang, MD

Q. What is the protocol for applying sunscreen?

A. It should be applied one-half hour before going outside, giving the skin time to absorb it. Because sunscreen tends to be broken down over time by the sun, and rubbed or washed off with sweating and water exposure, it should be reapplied at least every two hours outdoors, and immediately after swimming or heavy sweating. At least one ounce (two tablespoons) is needed to cover the entire body surface. 

As facial skin is thin and highly exposed, it is particularly important to apply sunscreen there liberally. Many sunscreens are now incorporated in facial moisturizing creams. In routine daily activity with no extended outdoor exposure, if the face is untouched and there is no sweating, it is acceptable to apply the sunscreen just once at the beginning of the day.

There is no need to throw away last year's left-over sunscreens. Shelf life is typically two to three years. Many sunscreens now have an expiration date stamped on the container. Store the sunscreen in a cool place, since heat can gradually break it down. 

Q.What does Sun Protection Factor (SPF) measure, and what are its limitations?

A. The SPF rating is a reliable measurement of protection against UVB (short-spectrum) wavelengths (290-320 nanometers; 1 nm is a billionth of a meter). SPF is the comparative ratio between the minimal erythemal dose (MED) – the time it takes for reddening or sunburn to start – in skin protected with sunscreen and the MED in unprotected skin. For example, if it takes 20 minutes without protection to produce erythema, an SPF 15 sunscreen might prevent reddening 15 times longer—about five hours. That figure is theoretical, however, and sun damage can occur even without reddening, so dermatologists normally advise reapplying after approximately two hours. 

The Skin Cancer Foundation considers SPFs of 15 or higher acceptable UVB protection for normal everyday activity, and SPFs of 30 or higher acceptable for extended or intense outdoor exposures. Such sunscreens also provide some protection against UVA wavelengths (320-400 nm), though the SPF rating refers only to UVB protection. Until 2011, no FDA-approved measurement standard existed for UVA protection in the US, even though such standards already existed abroad, and even though UVA penetrates more deeply into the skin than UVB, reaching the dermis. In the past, experts believed that UVB caused burning and skin cancer, while UVA caused photoaging, but the truth has proven more complex. In addition to producing sunburn, UVB can contribute to photoaging, and both UVA and UVB exposure can lead to skin cancer.

In June of 2011, the FDA issued its long-awaited new regulations for sunscreen labeling, including, for the first time, testing and labeling requirements for protection against UVA. These regulations will go into effect in December 2012, but products grossing under $25,000 in sales will have until December 2013 to comply with the new rules.

Sunscreens that meet FDA standards for both UVB and UVA protection may be termed “broad-spectrum,” a term that, until now, was frequently used but had no official meaning. Sunscreens may be labeled broad-spectrum if they provide “proportional” protection against both ultraviolet A (UVA) and ultraviolet B (UVB) radiation. In other words, a product with an SPF of 15 must have a comparable level of protection against UVA to be considered broad-spectrum.9 Newly standardized methods for measuring UVA protection made these improvements possible. Broad-spectrum sunscreens combine UVB- and UVA-absorbing chemicals and/or physical screens, and thus give the widest range of protection.  As of December, 2012, broad-spectrum sunscreens with an SPF of 15 or higher will be able to state that they reduce the risk of skin cancer and early skin aging caused by the sun, if used as directed with other sun protection measures. Sunscreens that are not broad-spectrum or that have an SPF of 2-14 will be required to have a warning stating that the product has been shown only to help prevent sunburn, not skin cancer or early skin aging.  

Read the Key Points in the FDA’s New Sunscreen Rules 

Q. Many people mistakenly believe that an SPF 30 rating gives twice as much sun protection as an SPF 15 and an SPF 50 more than three times that much. What is really the difference?

A. In vitro tests have shown that SPF 15 sunscreens filter out 93 percent of UVB rays, while SPF 30 protects against 97 percent and SPF 50 98 percent. But remember, it is important for the sunscreen to include broad-spectrum protection that also shields adequately against UVA. 

Q. Has the skin cancer protection afforded by sunscreen been documented?

A. In January 2011, definitive clinical research from Australia showed for the first time that sunscreen can drastically reduce melanoma incidence. Researchers found that daily application of an SPF 16 sunscreen to the head, neck, arms, and hands reduced melanoma incidence by 50 percent in subjects studied for more than a decade. Only 11 melanomas developed in the daily sunscreen users, vs. 22 in the control group. Even more impressively, invasive melanomas (those that penetrate beyond the skin surface) were reduced by 73 percent (3 tumors vs. 11), and those that were found in the sunscreen group were smaller on average and more readily curable.12 

There is also strong evidence that sunscreens protect against development of the precancerous skin condition actinic keratosis (AK), as well as squamous cell carcinoma. Studies performed in Australia and in the US have shown that regular use of sunscreen significantly decreases AK development,10,11 and since AKs can be a precursor to SCC, it is presumed that sunscreen can help prevent SCC. More recently, in a 4 1/2- year study involving over 1300 individuals, Australian researchers demonstrated that regular sunscreen use resulted in fewer SCCs, but did not significantly reduce BCCs.13

Q. What is the FDA's position on SPF limits?

A.  When the FDA announced its new regulations on sunscreen labeling in June 2011,  it also proposed a regulation that sunscreen manufacturers not be allowed to claim an SPF rating above 50; the highest rating would be 50+”. The Skin Cancer Foundation's Photobiology Committee agrees with this proposal, which remains under FDA consideration. High-risk individuals can, however, benefit from higher SPFs up to 45 or 50.14 

Q. What tests have been devised for measuring UVA protection?

A. Labeling of UVA protection in sunscreen is routine in a number of countries, including Australia, Japan and Germany, and in June, 2011, the FDA issued its first official guidelines on UVA protection for products sold in the US.14 The FDA has instituted a pass/fail test based on the critical wavelength value of 370 nm as its standard for acceptable broad-spectrum protection. In this widely used in vitro (lab-based) test, the UV absorption spectrum of the sunscreen is plotted against wavelength; the wavelength where 90 percent of absorption occurs is defined as the critical wavelength. Therefore, the more potent and broad the UVA protection, the longer the critical wavelength. Most consider a critical wavelength of 370 nm or longer as being good UVA protection.17  

In Europe and Asia, the most widely used in vivo UVA testing method (a test performed on live human subjects) is the Persistent Pigment Darkening test (PPD).15 The subjects are exposed to a UVA light source, with and without sunscreen. After two to three hours, darkening of the exposed skin is used as a biological endpoint. In treated subjects, the sunscreen should reduce darkening. 

A variation of the PPD method is the Protection Factor in UVA (PFA) test. Also an in vivo test, it measures either pigment darkening or erythema following UVA exposure as the endpoint.16 

Q. Is there any truth to the claim that a "base tan" helps prevent skin cancer?

A. No. Tanning is the skin's response to DNA damage, pure and simple. This damage may permanently affect the skin cells (melanocytes and keratinocytes).18 The activation and proliferation of these cells increase the risk of skin cancer and photoaging. UV tanning lamps can be as or more dangerous than the sun; in fact, their use has now been documented to be associated with all three major skin cancers.19 

There is no such thing as a healthy UV tan. Furthermore, The Skin Cancer Foundation considers tanning to be out of style and obsolete as a lifestyle. In fact, the Foundation’s Go With Your Own Glow campaign was developed to encourage women to embrace – and protect – their natural skin tone, whatever its hue.

However, for people who feel the need for bronzed skin, the Foundation maintains that spray tanning and self-tanners are safer than UV radiation exposure obtained outdoors or in a tanning bed. The active ingredient in most self-tanners, dihydroxyacetone (DHA), interacts with proteins in the skin to cause darkening without requiring UV exposure. While some recent research has questioned the safety of DHA tanning, the evidence is not convincing enough to change The Skin Cancer Foundation’s position that it is a safer, better alternative to UV tanning.  Although it temporarily adheres to the skin, DHA eventually dislodges as the skin cells shed. The Skin Cancer Foundation bases all of its conclusions on medical studies with human subjects, whereas most of the studies against DHA have been done in vitro (in a Petri dish). There are no human medical studies showing that DHA penetrates the skin, thus there is no clear evidence that DHA is harmful to humans if applied topically and used as directed. For those who get spray tans, it is important to wear protective gear for the mouth, eyes and nose to prevent ingestion or inhalation, and to protect mucous membranes. 

Some self-tanners include sunscreen. However, even if one with an SPF is used, a separate sunscreen should be applied after two hours outdoors and on subsequent times outdoors. 

Q. What are the basic sunscreen ingredients, and what protection does each offer?

A. Currently, 17 active sunscreen ingredients are approved by the FDA. The most recently approved ingredient is ecamsule (Mexoryl SX), approved in 2006. The FDA provides the approved concentration of each ingredient, and this often is included on the product's label. [See Table 2.]

Active Ingredient / UV Filter Name

Maximum FDA-approved Concentration, %

Range of Protection

Aminobenzoic acid












Ecamsule (Mexoryl SX)



Ensulizole (Phenylbenzimidazole Sulfonic Acid)






Meradimate (Menthyl Anthranilate)






Octinoxate (Octyl Methoxycinnamate)



Octisalate (Octyl Salicylate)






Padimate O






Titanium dioxide



Trolamine salicylate



Zinc oxide




Table 2. FDA-Approved Sunscreen Ingredients


Sunscreen ingredients fall into two categories: physical screens and chemical absorbers of UVR. Titanium dioxide and zinc oxide, commonly used today in micronized form for a more inconspicuous cosmetic look (these physical sunscreens formerly tended to be stark white on the skin), are used singly or combined with other active ingredients to protect against both UVB and UVA (titanium dioxide across the UVA2 spectrum, 320–340 nm; zinc oxide against both UVA2 and UVA1 — 340–380nm).

Chemical sunscreen ingredients that provide only UVB absorption are usually combined with others that cover some UVA wavelengths. UVB-absorbing organics include the cinnamates, with octinoxate (octyl methoxycinnamate) being the best known and most widely used; and the salicylates, most often octisalate (octyl salicylate) and homosalate. The benzophenone group of organics, including dioxybenzone, oxybenzone, and sulisobenzone, brought coverage into the UVA range, specifically offering protection against UVA2 as well as UVB.

Avobenzone, introduced in the early 1990s, extended chemical sunscreen protection into the UVA1 range (340–400 nm); it is currently the best UVA1 filter available in the US. It also offers some absorption across the UVA2 range. However, it does not provide adequate UVB protection, so it must be used in combination with UVB-absorbing ingredients. Until recently, the effectiveness of avobenzone was limited by its being photounstable, degrading by over 50 percent after one hour of sun exposure. Now, it has been photostablilized by combining it with other, photostable UV filters, such as octocrylene and/or oxybenzone.21 In patented new technologies such as HelioplexTM or Active Barrier Complex, diethylhexyl 2,6-naphthalate (DEHN), an electron acceptor, is used as another stabilizer of avobenzone. 

Anthelios SX, the broad-spectrum sunscreen product most recently approved by the FDA, includes the new ingredient ecamsule, also known as Mexoryl SXTM, which has been used in Europe and Canada for some years. Unlike avobenzone, Mexoryl SX is a photostable new generation of organic UV filter; it protects against the entire UVA2 spectrum. The formulation in Anthelios SX, combining Mexoryl SX with two other key active ingredients, avobenzone and octocrylene, is extremely stable, resulting in effective broad-spectrum coverage. Some tests show it to be effective in vitro for as much as five hours. (HelioplexTM technology is said to have a comparable effect.) Marketed as a daily facial moisturizer with sunscreen, it has an SPF of 15. Several new versions of Anthelios are available now as well, including versions with SPFs of 40, 45, and 50. 

Q. What other ingredients may be included in sunscreens?

A. Antioxidants, which to some degree can neutralize damaging “free radicals” (unstable, highly reactive oxidized molecules believed to cause tissue damage at the cellular level, harming our DNA), are sometimes added to sunscreens, though their impact is not universally accepted. Vitamin E (alpha tocopherol) gives some protection against UV-induced DNA damage, and vitamin C (L-ascorbic acid) helps protect against sunburn. The free radicals are produced by melanin and other skin tissues exposed to light. A number of sunscreens today list "free radical protection" on the package. 

Some products now combine sunscreen with the insect repellent DEET (diethylmethylbenzamide), oil of citronella and a biochemical substance known as IR3535. (When DEET and sunscreen are used separately, the repellent has been found to dilute the sunscreen below its stated SPF.) No good data are available on the efficacy of the combined products. One concern about them is the method and frequency of application, since sunscreens are to be reapplied liberally and frequently, while most insect repellents are to be applied no more often than every 6 hours. The FDA is considering specific regulation of these combination sunscreens, and the EPA also plans an evaluation.22 In the meantime, when you're using a combination product with DEET, reapply a separate sunscreen without the DEET after two hours, or immediately after swimming or heavy sweating. 

Q. Do moisturizers, tinted foundation, lipstick and other cosmetics containing an SPF 15 sunscreen provide as much protection as sunscreen used alone?

A. The cosmetics neither increase nor decrease the photoprotective value of the sunscreen. They have the great advantage that most women apply them every day. Some products for men also combine moisturizer and sunscreen. It's important, however, to use a separate sunscreen or reapply the cosmetics every two hours when outside. 

For the best results, if you are using a moisturizer and a separate sunscreen, the moisturizer should go on first, then sunscreen, then makeup. If you are also using a topical medication, that should be applied before everything else, then the rest of the layering process is repeated. 

Q. Are sunscreens more aesthetically pleasing and convenient than in the past?

A. Today, sunscreens that are excellent cosmetically and offer easier application are widely available. Consumers have a choice among lotions, creams, gels, sprays and sticks. Some are specially designed to appeal to children. "Micronized" versions of zinc oxide and titanium dioxide that render them invisible have greatly increased their popularity. And advanced technologies employing delivery systems such as liposomes (lab-created microscopic aqueous sacs enclosed in layers of fatty cells or their derivatives) enable sunscreen ingredients to stay on the skin surface better and keep their effectiveness longer. 

Q. Sunscreen still has its detractors. Some have claimed that it encourages excessive sun exposure by making people think they are totally protected from UVB and UVA, and thus increases their skin cancer risk. Is this valid?

A. Most photobiologists and dermatologists strongly disagree. Thorough analysis of all available data has failed to show any correlation between the use of sunscreen and an increase in melanoma or any other skin cancer.23,24 What’s more, combined UVA and UVB protection has vastly improved in recent years in sunscreens, extending the range of protection. However, it must always be remembered that broad-spectrum sunscreen is just one of several vital measures that need to be practiced in anyone's photoprotection program, along with seeking the shade during the sun’s most intense hours (generally between 10 AM and 4 PM) and wearing sun-protective clothing, including a wide-brimmed hat and UV-blocking sunglasses. 

Q. Is unprotected sun exposure necessary to prevent vitamin D deficiency?

A. This is a highly controversial issue.25,26 Vitamin D is synthesized when the skin is exposed to UVR. Its active form, 1,25dihydroxy Vit D 3, regulates calcium metabolism, essential for bone and muscle health, and recent epidemiologic studies have suggested that individuals with adequate serum vitamin D levels had a lower incidence of internal cancers and multiple sclerosis. However, in 2010, after extensive review, the Institute of Medicine determined that the benefits of vitamin D beyond bone health have not been conclusively proven.27 In any event, the action spectrum for cutaneous vitamin D synthesis is in the UVB range, known to be carcinogenic; staying out in the sun long enough to produce sufficient vitamin D exposes you to potentially harmful amounts of the sun’s UVB as well as UVA rays. 

Therefore, for individuals at risk for vitamin D insufficiency, such as those who are elderly, homebound, or dark-skinned, a balanced diet with adequate intake of food rich in vitamin D (e.g., salmon and fortified milk) is the most appropriate way to maintain a good vitamin D level, and vitamin D supplements can be added as necessary. The IOM recommends 600 International Units (IU) of vitamin D daily for all age groups between 1 and 70 years old. Because of its negative effects, intentional, unprotected sun exposure should not be used as a way to increase vitamin D level. Continue to use sunscreen and other forms of sun protection when you are outside. 

Q. How do sunscreens fit into an overall sun protection program?

A. The sun is an inevitable and enjoyable part of life, so daily use of a broad-spectrum SPF 15+ sunscreen (SPF 30+ for extended stays outdoors), applied liberally, must be a key part of any comprehensive sun protection program. The Skin Cancer Foundation also recommends seeking the shade, especially from 10 AM to 4 PM; avoiding sunburn; and covering up with clothing, including long-sleeved shirts, long pants, a broad-brimmed hat and UV-blocking sunglasses. 

Q. What is the easiest way to know if a sunscreen provides proper protection?

A. Besides checking the ingredient label, consumers can look for The Skin Cancer Foundation's Seal of Recommendation on the label or in the packaging. The Seal is awarded to sun protection products that meet the strict requirements of the Foundation's Photobiology Committee. 

In summer 2012, the Foundation implemented new standards for sunscreens in the Seal program. These new standards include effective UVA protection requirements. Sunscreens will also be divided into two categories based on their intended use – one called “Daily Use” and one called “Active.” 

“Daily Use” products are intended to protect consumers from incidental sun exposure that occurs in short periods of time. Examples of these products might include: daily moisturizers, color cosmetics, foundations, eye creams, lip balms, etc.  Requirements for the “Daily Use” Seal include: 

  • UVB protection of SPF 15 or higher
  • UVA protection with a Critical Wavelength of 370
  • Testing for contact irritancy and phototoxic reactions 

“Active” products should protect consumers from extended sun exposure, or during recreational activities. Examples might include: high-SPF products, sport sunscreens, zinc/titanium sticks, baby products, etc. Requirements for the “Active” Seal include: 

  • UVB protection of SPF 30 or higher
  • UVA protection with a Critical Wavelength of 370
  • Proof of water resistance (following the FDA guidelines, the product must specify whether it maintains its SPF after 40 or 80 minutes of water immersion)
  • Testing for contact irritancy and phototoxic reactions. 

Manufacturers must confirm that products in either category have been validated by testing on 10 people. 

Q. How will sunscreens continue to evolve?

A. Repair enzymes added to the mix will actually help correct any sun damage that occurs. To eliminate photosensitivity and allergic reactions, the ingredients will be less photoreactive. The availability of new photostable filters will continue to improve overall photostability. And sunscreens will be even more aesthetically pleasing and easier to apply.

Published on July 3, 2012



  1. US EPA. Sunscreen The Burning Facts. EPA 430-F-06-013. Sept. 2006.
  2. Armstrong BK, Kricker A. How much melanoma is caused by sun exposure? Melanoma Res Dec l993; 3(6)395-401.
  3. Rogers, HW, Weinstock, MA, Harris, AR, et al. Incidence estimate of nonmelanoma skin cancer in the United States, 2006. Arch Dermatol 2010; 146(3):283-287.
  4. American Cancer Society. Cancer Facts & Figures 2012. Accessed May 30, 2012.
  5. Pfahlberg A, Kolmel KF, Gefeller O. Febim. Study group timing of excessive ultraviolet radiation and melanoma: epidemiology does not support the existence of a critical period of high susceptibility to solar ultraviolet radiation-induced melanoma. Br J Dermatol Mar 2001; 144(3):471-5.
  6. Norval M. Immunosuppression induced by ultraviolet radiation: relevance to public health. Bull World Health Organ 2002; 80:11.
  7. Franceschi S, Levi F, Randimbison L, La Vecchia C. Site distribution of different types of skin cancer: new aetiological clues. Int J Cancer 1996 Jul 3; 67(1):24-8.
  8. Kricker A, Armstrong BK, English DR, Heenan PJ. A dose-response curve for sun exposure and basal cell carcinoma. Int J Cancer 1995; Feb 8; 60(4):482-8.
  9. U.S. Dept. of Health & Human Services, FDA U.S. Food and Drug Administration, Questions and Answers: FDA announces new requirements for over-the-counter (OTC) sunscreen products marketed in the U.S. Accessed August 19, 2011.
  10. Thompson SC, Jolley D, Marks R. Reduction of solar keratoses by regular sunscreen use. N Engl J Med 1993 Oct 14; 329(16):1147-51.
  11. Naylor MF, Boyd A, Smith DW, Cameron GS, Hubbard D, Neldner KH. High sun protection factor sunscreens in the suppression of actinic neoplasia. Arch Dermatol 1995 Feb; 131(2):170-5.
  12. Green AC, Williams GM, Logan V, Strutton GM. Reduced melanoma after regular sunscreen use: randomized trial follow-up. Journ Clin Oncol Jan 2011; 29:3:257-263.
  13. Green AC, Williams G, Neale R, Hart V, Leslie D, Parsons P, et al. Daily sunscreen application and betacarotene supplementation in prevention of basal-cell and squamous cell carcinomas of the skin: a randomised controlled trial. Lancet 1999 Aug 28; 354(9180):723-9.
  14. U.S. Dept. of Health & Human Services, FDA U.S. Food and Drug Administration. FDA sheds light on sunscreens. Accessed August 19, 2011.
  15. Moyal D, Wichrowski K, Tricaud C. In vivo persistent pigment darkening method: a demonstration of the reproducibility of the UVA protection factors results at several testing laboratories. Photodermatol Photoimmunol Photomed 2006; Jun 22(3):124-8.
  16. Cole C. Sunscreen protection in the ultraviolet A region: how to measure the effectiveness. Photodermatol Photoimmunol Photomed 2001; 17:2-10.
  17. Diffey BL, Tanner PR, Matts PJ, Nash JF. In vitro assessment of the broad-spectrum ultraviolet protection of sunscreen products. J Am Acad Dermatol 2000 Dec; 43(6):1024-35.
  18. Agar N, Young AR. Melanogenesis:a protective response to DNA damage. Mutat Res 2005 Apr 1; 571(1-2):121-122.
  19. International Agency for Research on Cancer Working Group on artificial ultraviolet (UV) light and skin cancer. The association of use of sunbeds with cutaneous malignant melanoma and other skin cancers: a systematic review. Int J Cancer 2007; 120:1116-1122.
  20. Lim HW, Wang SQ. The Skin Cancer Foundation’s guide to sunscreens. The Melanoma Letter 2007; 25:2:1-6.
  21. Kullavanijava P, Lim HW. Photoprotection. J Am Acad Dermatol 2005; 52:937-958.
  22. Food and Drug Administration. Insect Repellent- Sunscreen Drug Products for Over-the-Counter Human Use. Federal Register Feb. 22, 2007; 72:35:7941-745.
  23. Dennis LK, Beane Freeman LE, VanBeek MJ. Sunscreen use and risk of melanoma: a quantitative review. Ann Intern Med 2003; 139:966-78.
  24. Huncharak M, Kupjelnick B. Use of topical sunscreens and the risk of malignant melanoma: a meta-analysis of 9067 patients from 11 case-control studies. Am J Public Health 2002 Jul; 92(7):1173-7.
  25. Lim HW, Gilchrest BA, Cooper KD, Bischoff-Ferrari HA, Rigel DS, Cyr WH, et al. Sunlight, tanning booths, and vitamin D. J Am Acad Dermatol 2005 May; 52(5):868-76.
  26. Wolpowitz D, Gilchrest BA. The vitamin D questions: how much do you need and how should you get it? J Am Acad Dermatol 2006 Feb; 54(2):301-17.
  27. Institute of Medicine of the National Academies. Report Brief. Dietary Reference Intakes for Calcium and Vitamin D, released 11/30/10. Accessed August 19, 2011.


Henry W. Lim, MD
Chairman and C.S. Livingood Chair
Department of Dermatology
Henry Ford Hospital, Detroit

Steven Q.Wang, MD
Director, Dermatology
and Dermatologic Surgery
Memorial Sloan-Kettering Cancer Center
Basking Ridge, NJ

© 2012 The Skin Cancer Foundation, Inc.