Life Extension Magazine

Life Extension Magazine June 2006

Report

The Sunscreen ParadoxPopular Misconceptions About Skin Cancer Prevention

By Steven V. Joyal, MD

People apply sunscreen to protect against sunburn, skin aging, and skin cancer. Because of the way sunscreen products are labeled by FDA mandate, consumers are often confused about which ingredients they need to achieve optimal protection against the sun’s damaging and deadly rays.

Fortunately, scientific data have emerged indicating that health-conscious individuals can achieve broad-spectrum protection against the increasing onslaught of ultraviolet light penetrating our atmosphere.

Like clockwork, the sound bites occur on television news programs at the start of the summer season:

“To prevent skin cancer and premature aging of the skin, apply sunscreen before going out in the sun.”

Well known to scientists, physicians, and the average person alike, sun exposure is the main environmental risk factor for skin cancer,1 and sunburn is a well-established risk factor for skin cancer.2

Sun exposure in the form of ultraviolet light not only accelerates skin aging, but can also result in debilitating disfigurement from skin cancer. Some types of skin cancer can even lead to premature death. Furthermore, we are in the midst of a veritable epidemic of skin cancer. The incidence of basal and squamous cell carcinoma is increasing, as is the occurrence of deadly malignant melanoma, a dangerous form of skin cancer that develops in the pigment-producing cells of the skin, known as melanocytes.

Conventional wisdom indicates that, in addition to avoiding sun exposure, sunscreen is your best bet for preventing skin cancer. However, the sun protection factor (SPF) rating system used by the FDA to regulate sunscreen products has an inherent flaw that renders its ratings dangerously inaccurate. This may create a false and potentially disastrous sense of security in sunscreen users.

Melanoma Mortality

The American Cancer Society estimates that the mortality rate from melanoma has increased 50% since 1973. Nearly 8,000 Americans die of the disease every year.3

Flaws in the SPF Rating System

Basal cell and squamous cell skin cancers are caused primarily by a particular spectrum of sunlight called ultraviolet B, or UV-B. It is UV-B radiation that also causes sunburn. The FDA’s SPF rating system rates sunscreen for protection against UV-B light, but not against ultraviolet A (UV-A) light.

UV-A, the longer-wavelength ultraviolet light, penetrates deeper than UV-B through the outer portion of the skin. This is very important, because UV-A damage is largely responsible for premature aging of the skin. Moreover, UV-A light exposes the melanocytes, which are the pigment-producing cells in the skin, to damage that can potentially result in malignant melanoma, the deadliest form of skin cancer.

Thus, despite slathering on sunscreen and not developing a sunburn (because of protection against burning UV-B rays), we can still develop a light tan because the UV-A rays are penetrating the skin.

To protect your skin, you need broad-spectrum protection against both UV-A and UV-B rays. You cannot rely solely on the SPF rating system, because it provides information only on UV-B protection.

The only way to be sure that your sunscreen provides UV-A protection is to read the label and make sure it contains effective UV-A blocking agents, which include avobenzone, oxybenzone, zinc oxide, and/or titanium oxide.

Lawsuit Accuses Sunscreen Makers of False Claims

A lawsuit filed in Los Angeles Superior Court in March accuses the nation’s leading sunscreen

makers of making false and misleading claims about the effectiveness of their products. Given that the sunscreen products are manufactured and marketed in compliance with FDA regulations, the lawsuit underscores the problematic SPF rating system, and the dangers of relying on the FDA’s flawed SPF (sun protection factor) rating system to protect against cancer and other sun-induced health dangers.

The lawsuit charges sunscreen makers such as Coppertone, Banana Boat, Hawaiian Tropic, and Neutrogena with making inflated claims about the safety and effectiveness of their products, and thus giving consumers a false of security about the health consequences of prolonged sun exposure.

The lawsuit targets product labels claiming that the sunscreens protect equally against harmful UV-A and UV-B rays, as well as claims concerning how long so-called waterproof sunscreens actually remain effective in water. While sunscreens are graded for protection against UV-B rays, research indicates that the FDA’s SPF rating system does not assess for protection against longer-wavelength UV-A rays, which can contribute to skin cancer, aging, and wrinkling.

The suit also takes aim at claims made in labels for sunscreen products developed specifically for children, such as Schering-Plough’s Coppertone Water Babies. The lawsuit alleges that, in fact, the Coppertone product provides protection only against UV-B rays.

Sunscreens, Topical Antioxidants, and Free Radical Damage

No matter what the ads promise, sunscreens alone inadequately protect against sunlight’s damaging, free radical-generating effects. In a study using special techniques to detect free radical damage to human skin after ultraviolet light exposure, application of conventional sunscreen with an SPF of 20+ resulted in a “free radical protection factor” of only 2!5

Ultraviolet light generates harmful free radicals such as the superoxide anion radical, hydrogen peroxide, the hydroxyl radical, and singlet oxygen, in addition to lipid peroxides.6

Studies demonstrate the critical importance of topical antioxidant protection to quench the free radicals generated by UV light that sunscreens miss. For example, adding simple antioxidants like vitamin E acetate and sodium ascorbyl phosphate (a stable form of vitamin C used topically) to a conventional sunscreen formula can decrease free radicals in the skin better than sunscreen alone.7 In addition, when antioxidants are combined with conventional sunscreen, greater-than-expected protection is achieved against sun damage.8

FDA Fails to Warn Public of UV-A Dangers

It is bizarre but true—the FDA appears to recognize the limitations of its SPF rating system for sunscreen, yet has done nothing of substance to remedy the problem!

Back in 2000, the FDA discussed some of these issues in its consumer magazine, in which it described the inadequacy of UV-A rating as an “unresolved technical dilemma.”4

Six years later and counting, the FDA’s “unresolved technical dilemma” remains unresolved, while the population remains at risk. Is it any surprise that skin cancer has reached epidemic proportions?

Vitamin D and Cancer Protection

Epidemiological studies suggest that sunlight exposure is associated with a decreased risk of non-Hodgkin’s lymphoma, a type of cancer of the lymph glands.14,15 Such studies also suggest that ultraviolet light exposure is associated with a lower risk of developing breast, colon, endometrial, esophageal, and ovarian cancer.16 Furthermore, death rates from cancers of the breast, prostate, and colon are higher in northern latitudes (which receive less sun exposure) than in southern latitudes (which enjoy relatively greater sun exposure).17

The question, then, is how could sunlight protect against cancer?

Vitamin D, synthesized in your skin after exposure to UV-B light, has a number of documented anti-cancer effects, including inhibiting cancer cell growth and promoting normal cell cycle activity.18-20

Interestingly, the active form of vitamin D generated by sun exposure on the skin—1,25-dihydroxyvitamin D3—is low in patients with malignant melanoma, the deadliest of skin cancers.21 Melanoma cell lines express the vitamin D receptor, and 1,25-dihydroxyvitamin D3 acts to decrease cancer cell growth as well as push the cell toward a more mature cell form. Medical scientists know that more immature cell types are seen with cancers that are more aggressive.

Although a very controversial idea, exposure to natural sunlight may be protective against melanoma. Recall that UV-B rays stimulate vitamin D in the skin, and vitamin D is likely protective against melanoma. Remember, too, that sunscreens that block UV-B but not UV-A rays will also block vitamin D production in the skin. This may be a deadly double whammy: no synthesis of protective vitamin D in the skin, yet exposure to the deeply penetrating UV-A rays.

A Risk/Benefit Approach to Sun Exposure

Given all the information available, what is the best sun exposure strategy—one that balances the risks and potential benefits?

As individuals, we each have a very different tolerance for sunlight exposure. For example, equatorial Africans have a much higher degree of natural protection from the sun than do people of northern European ancestry. In addition, there are many hypotheses in alternative medical circles regarding potential links between skin cancer and dietary overconsumption of omega-6 fatty acids, inadequate hormone status, and other factors. There may very well be some validity to such theories, but until more is known, the best strategy is to be prudent with regard to sun exposure.

This means that for many of us, brief exposure to sunlight (10-15 minutes, two to three times weekly) should allow adequate time for vitamin D synthesis by the skin, without greatly increasing the risk of skin cancer.22 Additional supplemental vitamin D (for example, 800 IU a day and higher) will be needed, however, because this short duration of UV-B exposure is unlikely to be sufficient for optimizing vitamin D status.

For people of northern European ancestry or those looking to minimize premature skin aging, sun exposure beyond 10-15 minutes should be accompanied by liberal application of a sunscreen with broad UV-spectrum protection and generous use of topical agents with demonstrated protective effects against free radical damage.

Protect Yourself Against UV-8 and UV-A

The best skin-protection strategy combines a blend of sunscreens that provide broad-spectrum protection against both UV-A and UV-B light.9 Some ingredients, such as zinc oxide, physically block the penetration of UV-A and UV-B rays into the skin. Other sunscreen ingredients like octinoxate, also known as octyl methoxycinnamate, protect the skin not only against sunburn, but also against UV light-induced damage to cellular DNA.10,11

Always make sure that your sunscreen contains a blend of ingredients to achieve broad-spectrum UV-A and UV-B protection.

Zinc oxide in particular has come a long way from the glop that many of us remember smearing on our noses when we were children. Applications of microfine zinc oxide preparations appear to be almost invisible and provide great wide-spectrum UV-A and UV-B blockage.12 Zinc oxide has other important skin benefits besides physically blocking UV light. For example, topical zinc oxide helps skin wounds to heal faster.13

A critical point with regard to sunscreen is to use plenty of it—slather it on! Many people use far too little sunscreen to obtain its maximum benefits.

Ingredient

UV-B protection

UV-A protection

Avobenzone

No

Yes
(but degrades rapidly after application
and is a potential skin irritant)

Oxybenzone

No

Yes
(more stable than avobenzone and
less likely to be a skin irritant)

Zinc oxide

Yes

Yes

Octyl methoxycinnamate

Yes

No

Titanium dioxide

Yes

Yes