Most people who go out into the sun wearing sunscreen and don’t end up with a sunburn probably think their skin was adequately protected.
This is often far from the truth. Here’s why.
First, many sunscreens contain anti-inflammatory chemicals that can prevent skin from looking burned sunburn even if they’re applied after you’re home from the beach. In the absence of painful sunburn, sunscreen users can falsely assume they were fully shielded from the harmful effects of UVB rays, when in fact they essentially were duped by a chemical trick.
Second, many sunscreens don’t provide adequate protection from UVA rays. Higher-energy UVB rays are the primary cause of sunburns and pre-cancerous DNA mutations, but UVA rays cause more subtle damage. They penetrate deeper into skin tissue and are most responsible for generating free radicals – energized molecules that are highly reactive and can damage DNA and skin cells (Marrot 2005), promote skin aging (Wlasckek 2001) and cause skin cancer.
Laboratory tests show that most of the FDA-approved UV filters in sunscreens release free radicals when struck by UV radiation (Allen 1996, Beeby 2000, Cantrell 1999, Damiani 2007 Damiani 2010, Dondi 2006, Hidaka 2006, Knowland 1993, Sayre 2005, Serpone 2002). This is a deliberate strategy for diffusing the intense energy of UV rays, but it also suggests that sunscreens should be carefully formulated and tested to ensure they offer the strongest and most lasting protection from the damage of free radicals.
Laboratory testing to measure free radical generation has shown that fewer free radicals form in sunscreen-protected skin than in unprotected skin. In other words, sunscreens typically do more good than harm in preventing UV-induced free radicals (Popov 2009, Serpone 2006, Haywood 2003). But they should be better.
One study found a 45 percent reduction in formation of free radicals when sunscreen was used in typical amounts and a 55 percent reduction when it was used at the recommended amount – two milligrams per square centimeter of skin (2 mg/cm2). Translated to an SPF-style index, this would be equivalent to a “free radical protection factor” of 2, in contrast to the common sunburn protection factors (SPF) of 15 to 50 (Haywood 2003). Follow-up studies measured free radical protection factors of around 2 to 4 in SPF 15 sunscreens containing either avobenzone or titanium dioxide for UVA protection (Haywood 2012).
Applying too little sunscreen or reapplying it too infrequently diminishes protection against free radical formation. Consumers commonly apply a much thinner coating of sunscreen than recommend on the product label. One study found that after one hour of UV-exposure, the number of free radicals on skin treated with three sunscreen ingredients was actually higher than on untreated skin (Hanson 2006). This study supported the notion that reapplying sunscreen frequently is essential.
The sunscreens with the best UVA protection are best at suppressing free radical formation (Wang 2012b). Inadequate UVA protection is a persistent problem in products sold on the U.S. market. UV rays quickly break down avobenzone, the most common UVA filter in American sunscreens, unless it is mixed with a stabilizer. European sunscreens appear to provide greater free radical protection because they can contain superior UVA filters. In tests, 12 European sunscreens averaged a free radical protection factor of 13 (Wang 2011).
The FDA’s weak regulations allow nearly every sunscreen to claim “broad spectrum,” or UVA, protection, even though some are much better than others. These weak rules give manufacturers little incentive to improve their products.
To be truly effective at preventing skin damage and skin cancers, U.S. sunscreens need to provide better protection from UVA rays. This will not happen until the FDA sets higher requirements for UVA protection and approves the use of modern sunscreen ingredients with superior UVA filtering and stability.
The FDA should ban the sale of sunscreens that provide poor UVA protection or approve a labeling system that classifies UVA protection as low, medium or high to enable consumers to choose the best products.
In the absence of truly protective regulations, consumers are in the worst possible position: they are likely to think that their sunscreen is providing more protection than it really is, so they stay out longer in the sun and thereby increase their risk of skin cancer and skin damage.
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