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By Laura J. Goodman
Posted: March 26, 2008, from the April 2008 issue of Skin Inc. magazine.
With the sun being such an essential part of life and so influential on a person’s psyche, it can be easy to forget that the rays it gives off are the enemy in the battle against skin damage and aging. Many people are beginning to see the effects of youthful days spent basking in the sun, dripping with baby oil instead of sunscreen, so now it is more important than ever to get the straight facts on sun care.
Research proves exposure to UV, or ultraviolet, radiation causes damage to the skin, and studies also prove sunscreens are effective at protecting skin from this damage.1–8 As a skin care professional, getting to know the facts, keeping up-to-date on scientific developments and being a resource to family, friends, clients and colleagues is essential to yourself and your business.
Studying information on the subjects of solar UV radiation and sunscreens—including the changes that may result from an impending amendment to the FDA sunscreen monograph, which is explained in further detail later in this article—you’ll find a range of important sun care knowledge and resources in the following. Incorporate this learning into your daily life, and use it to be a knowledgeable influence for the people you come in contact with every day.
The ABCs of solar UV radiation
UV light is described as three wavelengths: UVA, UVB and UVC. UVC is currently absorbed by the ozone layer of the Earth’s atmosphere, so nearly all concern about ultraviolet radiation centers around protection from UVA and UVB rays.
UVB is only partially absorbed by the ozone layer, and the UVB rays that do penetrate the atmosphere are responsible for causing harmful sunburns, as they enter just below the skin’s surface into the epidermal layers. Transmission of UVB peaks when the sun is high in the sky, traditionally between the hours of 10 AM and 2 PM, making it less dangerous in the early morning and
late evening hours. Also, UVB can be blocked to some extent by very dense clouds, layers of clothing and glass.
Consequently, an estimated 95% of the UV rays that reach the earth are UVA rays. UVA penetrates deeper into the skin than UVB, causing damage into the dermal layers, which research has linked to premature aging and wrinkle formation.9 UVA can penetrate cloud cover, light clothing and untinted glass, as well.
Also, both UVB and UVA have been linked to the production of cancer, so protecting the skin from these harmful rays is essential for good health.
How do sunscreens work?
The primary function of a sunscreen product is to reduce the dose of solar UV the skin receives, protecting it from the damaging effects of UV radiation. In order to provide this protection, sunscreen products contain ingredients that absorb, reflect and scatter UV radiation, thus abating the radiation before it can penetrate into the skin and damage key components, such as DNA, collagen and elastin. Much like an umbrella shields you from the unwanted effects of rain, sunscreen shields you from the unwanted effects of solar UV.
Be aware that sunscreen ingredients reduce the dose of solar UV to varying degrees. Each sunscreen ingredient absorbs UV across a specific range, so it is important to use a product containing an effective combination of ingredients in order to truly get broad-spectrum protection.
Sun protection factors—what do they mean?
Austrian scientist Franz Greiter introduced sun protection factor, or SPF, as a standard measure of sun protection more than 40 years ago. An SPF number indicates protection against erythemally induced skin effects, such as redness, inflammation and sunburn, which are weighted for UVB.
However, SPF is really more complex than most people realize, and this lies mostly in the fact that sun protection factors are not linear. For example, SPF 30 does not block twice as much erythemally weighted UV as SPF 15. In reality, SPF 30 blocks 97% of erythemally weighted UV, while SPF 15 blocks 93%. See Fig. 1 for further explanation and examples.
The FDA standard dose for SPF testing is 2mg/cm2—approximately enough to fill a shot glass—which is, on average, equal to the amount needed to cover the entire body. Applying two layers of sunscreen assures more even, continuous coverage, and it more than doubles the SPF on the skin. Additionally, applying half of the effective dose of an SPF 30 will not result in an SPF 15, but more likely an SPF 7 or 9.
At this time, there is no universal test method or standard product label to indicate the level of UVA protection in sunscreens. The Food and Drug Administration (FDA) is, however, currently reviewing a proposed amendment to the sunscreen monograph that will incorporate test methods and labeling for UVA protection.
The FDA sunscreen monograph—what is it?
In the United States, sunscreen products are regulated as over-the-counter, or OTC, drug products and must comply with rules presented in the sunscreen monograph, created and enforced by the FDA. The legal difference between a cosmetic and a drug is determined by a product’s intended use, and different laws and regulations apply to each type of product. Manufacturers sometimes violate the law by marketing a cosmetic with a drug claim or by marketing a drug as if it were a cosmetic without adhering to requirements for drugs, so the FDA has published monographs, or rules, for a number of OTC drug categories.
These monographs, which are published in the Federal Register, state requirements for categories of nonprescription drugs, such as what ingredients may be used and for what intended use. Among the many nonprescription drug categories covered by OTC monographs are acne medications; treatments for dandruff, seborrheic dermatitis and psoriasis; and sunscreens.
The sunscreen monograph rulemaking began in 1978, and the final monograph was issued in 1999, only to be put on hold in 2001 until more reliable testing methods for UVA sunscreen protection could be developed. A proposed amendment of the final monograph was issued in August 2007. “The rule, if finalized, will set long-awaited standards for testing and labeling OTC sunscreen products providing UVA and UVB protection,” says J. F. Nash, PhD, principal scientist with P&G Beauty.
An international group of beauty professionals has been working to establish technical standards for sunscreens through the International Standards Organization, and Nash and others have estimated the final monograph will be published mid-2009. That would be followed by an 18-month implementation period, making changes in sunscreen product testing and labeling most likely to be effective around late 2010 or early 2011.
Possible monograph changes
The proposed regulations specify that SPF comes to mean sunburn protection factor rather than simply sun protection factor, which is only a measure of UVB efficacy.* Methods of measurement for SPF will be unchanged for the most part, with SPF numbers likely to be capped at 50+ and the following category descriptions mandatorily accompanying each bottle’s SPF number:
SPF 2–14 = low
SPF 15–29 = medium
SPF 30–50 = high
SPF 50+ = highest
UVA efficacy will be quantified by a combination of in vitro, or tested on an artificial substrate, and in vivo, or tested on human skin, methods to establish a UVA efficacy rank. The lower result of the two compulsory tests determines the rank, which is then communicated to the consumer via Product Category Descriptors of low, medium, high and highest, along with the appropriate corresponding star symbols, making the UVA ranking semi-independent of the SPF. The star symbols will likely appear as follows:
No UVA efficacy (Four empty stars)
Low (One colored star, three empty ones)
Medium (Two colored stars, two empty ones)
High (Three colored stars, one empty one)
Highest (Four colored stars)