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Screening Sunscreens

July 23, 2008

Screening Sunscreens

Summer is here and there is no better time to be outdoors. Yet, it is also a time in which it is important to protect oneself from the harmful effects of the sun. Skin cancer is the most common form of cancer in the United States with rates of occurrence increasing approximately 3% each year since 1981. One in 5 Americans will develop skin cancer in the course of a lifetime and over 1 million skin cancers (malignant and non-malignant) are diagnosed annually.

The sun emits visible light, heat, and ultraviolet radiation (UV). During the summer months, the UV rays emitted from the sun are stronger. There are 3 types of UV radiation: UVA, UVB, and UVC. Radiation from the sun is classified by wavelengths, which describe the distance in the peaks of the waves. UVA rays have the longest wavelengths, followed by UVB, and UVC rays. The UVA and UVB rays are transmitted through the atmosphere; however, the UVC rays are screened by the Earth’s ozone layer. The majority of UV rays that a person comes into contact with are UVA and a small amount of UVB.

Both UVA and UVB rays can cause damage to the skin. Sunburn is a sign of short-term overexposure, while premature aging and skin cancer are side effects of prolonged UV exposure. UVA rays penetrate deep into the skin and it is thought that exposure causes skin to sag, increases thickness of the skin, and decreases skin elasticity. UVB rays are the most intense, cause sunburns, and are linked to skin cancers. They also cause wrinkling and collagen damage.

Despite the harmful effects of radiation from the sun, there are some health benefits. Brief exposure, about 5 to 15 minutes twice a week, helps the body produce vitamin D. However, the amount of exposure needed depends on several factors, including geographical location, the time of day, and the time of year. Phototherapy is UV radiation in the form of lasers, lamps, or a combination of these devices with topical medications that increase UV sensitivity. This is sometimes used to treat patients with certain diseases who have not responded to other methods of therapy. Such diseases include: rickets, psoriasis, eczema, vitiligo, and lupus. Phototherapy is always administered under the direction of a physician and careful consideration is needed to ensure that the benefits of phototherapy outweigh the risks.

Earlier this month, The Environmental Working Group (EWG) released the results of a study that found that many sunscreens provide inadequate protection from the sun. Nine hundred fifty-two brand-name products, including Banana Boat, Coppertone, Hawaiian Tropic, and California Baby, were evaluated for safety and efficacy. In this study, the list of ingredients for each product evaluated was obtained from online retailers. Health hazard ratios were created to rate product effectiveness for providing sun protection based on 3 factors:

1. UVB protection – using the labeled sun protection factor (SPF)
2. UVA protection – using a standard model of absorbance
3. Stability – review of studies of the rate of sunscreen degradation

The following table reports the outcomes of the study, with the number of products listed for each category. Sunscreens that are preferred for use are those that were shown to be effective and of low hazard (safe). The sunscreens that are not effective, and have been shown to be unsafe, are not recommended for use. Products evaluated were not differentiated for children or adults.

Table 1. Hazard rates vs. efficacy for 952 sunscreens.

Additionally, the results of the evaluation showed:

• Only 15% of the products analyzed met the EWG’s criteria for safety and efficacy
• Most products provide protection from UVB rays (sunburn) and minimal protection against UVA rays
• Many sunscreens contain ingredients that breakdown in the sun; therefore, they may not offer protection for the length of time specified on product labeling
• Product claims on package labeling may be misleading, such as broad-spectrum protection, all day protection, waterproof, and free of chemicals
• Zinc oxide and titanium are effective ingredients against UVA rays and penetrate healthy skin; however, many sunscreens contain minimal amounts of these agents, so consumers may not experience the full effects of these ingredients
• Europe and Asia offer products that are more effective than those approved by the Food and Drug Administration (FDA)
• Ingredients in some sunscreens may penetrate into the blood, which could lead to adverse effects, or the ingredients may cause allergic reactions in a large population of individuals

The alarming results of this study may prompt the FDA to move forward on providing mandatory standards for sunscreens. In August 2007, the FDA proposed that manufacturers of sunscreens include information on UVA protection. The proposed rule would establish a consumer-friendly, 4-star rating system that would rate the level of UVA protection from “low” (1 star) to “highest” (4 stars). For example, a sunscreen product providing medium UVA protection would be labeled:

If the sunscreen was found to provide no UVA protection, the label would read, “No UVA Protection.” This information would be included on the bottle along with the SPF labeling for UVB protection.

The EWG has published a comprehensive sunscreen guide to help consumers choose the most effective products. The top 10 recommended common brands are listed in table 2. Go to http://skindeep.ewg.org/special/sunscreens/ewg_sunscreen.pdf for a quick reference guide for additional sunscreen tips.

Table 2. Top 10 recommended products from the EWC.

References:

Skin Cancer Foundation. 2008 Skin Cancer Facts. http://www.skincancer.org/content/view/317/78/. Accessed July 10, 2008.

DeSimone EM. Prevention of sun-induced skin disorders. In: Berardi RR, McDermott JH, Newton GD, eds. Handbook of Nonprescription Drugs. 14^th ed. Washington, DC: American Pharmacists Association; 2004:929-953

Food and Drug Administration. Tanning: ultraviolet (UV) radiation. http://www.fda.gov/cdrh/tanning/uvradiation.html. Accessed July 15, 2008.

Environmental Working Group. Overall scores of 952 sunscreens. http://www.cosmeticsdatabase.com/special/sunscreens2008/findyoursunscreen.php?nothanks=1. Accessed July 9, 2008.

Food and Drug Administration. Summary of key points on over-the-counter sunscreen products. http://www.fda.gov/cder/drug/infopage/sunscreen/key_points.htm. Accessed July 11, 2008.

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