Whats wrong with high SPF?

Theoretically, applying SPF 100 sunscreen allows beachgoers to bare their skin to sunshine a hundred times longer before causing the skin to burn: Someone who would normally redden in 30 minutes could remain in the sun for 50 hours before a burn would appear.

But for high-SPF sunscreens, theory and reality are two different things. Studies have found that users of high-SPF sunscreens have similar or even higher exposures to harmful ultraviolet (UV) rays than people relying on lower SPF products. The reason: People trust the product too much, go too long before reapplying it and stay out in the sun too long (Autier 2009).

In 2007, the FDA published draft regulations that would prohibit companies from labeling sunscreens with an SPF (sun protection factor) higher than “SPF 50+.” The agency wrote that higher values would be “inherently misleading,” given that “there is no assurance that the specific values themselves are in fact truthful…” (FDA 2007).

Since then FDA has been flooded with data from sunscreen makers seeking to win agency approval for high-SPF products, and store shelves have been increasingly packed with high-SPF products the agency has yet to validate. Johnson & Johnson (makers of Neutrogena and Aveeno sunscreens) submitted data in August 2008 to support SPF 70 and SPF 85 claims (J&J 2008). Playtex (Banana Boat sunscreen) sent data supporting high SPF claims in 2007. A Coppertone spokeswoman said, “Many manufacturers, including Coppertone, have submitted new data [on high-SPF products] for review and are awaiting FDA’s response” (Boyles 2009).

High-SPF sunscreens are popular. Sales have been on the rise for at least a decade, so it’s no wonder that sunscreen makers are fighting to keep them legal. In a letter to FDA 10 years ago, Neutrogena cited consumers’ clear demand for high SPF products, calling them “one of the fastest growing segments” of the market (Neutrogena 2000). Between 2004 and 2008, sales of high-SPF products in Europe (SPF 40 and 50+) swelled from 15 percent to 20 percent of the market (Jones 2010). In 2010, sunscreen makers have once again increased their high-SPF offerings in the US. Nearly one in six products now lists SPF values higher than “SPF 50+”, compared to only one in eight the year before, according to EWG’s analysis of nearly 500 beach and sport sunscreens.

Here’s what’s wrong with high-SPF sunscreens:

Extended sun exposure, same number of sunburns

Users of high-SPF sunscreens stay in the sun longer with a single application and get burned when the product’s chemicals break down, wash off or rub off on clothes and towels. Armed with a false sense of security, they extend their time in the sun well past the point when users of low-SPF products head indoors. As a result, they get the same number of sunburns as unprotected sunbathers and absorb more damaging UVA radiation, which many high-SPF products do not effectively block.

People seeking “intentional sun exposure” are most at risk from high-SPF products. In contrast to landscapers, gardeners, baseball players and others who spend defined times outdoors for specific jobs (“nonintentional sun exposure”), people in the intentional exposure category intend to tan or otherwise expose large areas of bare skin to the sun for prolonged periods (Autier 2009).

Studies of volunteers on summer vacation in France, Switzerland and Belgium found that those using high-SPF products extended their sunbathing time by 19-to-25 percent, used the same amount of sunscreen as those using low-SPF products, were likelier to start sunbathing at noon instead of the later hours chosen by the low-SPF users and got the same number of sunburns. From these studies it appears that by delaying sunburn, high-SPF products take away a key warning of UV overexposure. Sunbathers stay out longer and soak up more radiation, especially in the UVA range where sunscreens are relatively ineffective (Autier 2009).

Philippe Autier, a scientist at the International Agency for Research on Cancer, concluded that high-SPF products spur “profound changes in sun behavior” that may account for the increased melanoma risk found in some studies. He advises that people seeking sun exposure “should be advised not to use sunscreen but rather to let their skin adapt and set strict limits on the time they spend in the sun” (Autier 2009). Though his conclusion has not been adopted wholesale by public health agencies, it is grounded in a growing body of evidence that raises basic questions about the efficacy of sunscreen for sunbathers and others intentionally seeking sun exposure.

Clothing is an effective alternative. One study found that melanoma risk was cut by 52 percent for parts of the body usually covered by clothing during summer outdoor work (Holman et al 1986). EWG believes that hats and shirts are the best sunscreen of all.

Increased exposure to potentially hazardous ingredients

High-SPF products contain greater amounts of sun-blocking chemicals than low-SPF sunscreens. These ingredients may pose health risks when they penetrate through the skin, where they have been linked to tissue damage and potential hormone disruption. If studies supported a reduction in skin damage and skin cancer risk from high-SPF products, the additional exposures might be justified. But they don’t, so choosing sunscreens with lower amounts of active ingredients – SPF 30 instead of SPF 70, for example – is prudent.

SPF factors are based on two-to-five times more sunscreen than people actually use

In the real world, people get far less protection than the bottle advertises.

Sunscreen makers establish a product’s SPF by testing their products on volunteers. The testers coat the volunteers’ backs with 2 milligrams of sunscreen per square centimeter of skin (mg/cm2), the amount stipulated in FDA’s draft sunscreen regulations (FDA 2007), and then expose them to sunlight-simulating UV radiation until a burn appears. The time needed to burn, divided by the time it takes to burn the volunteers’ unprotected skin, is the SPF.

In real life, people apply one-half to one-fifth the amount of sunscreen used in the laboratory SPF tests (Autier 2003, Azurdia 2001, Reich 2009). Because of the physics of sunlight, that cuts the protection factor not by a factor of just 2 to 5, but by between the square root and the fifth root of the SPF. That’s a much steeper “exponential” cut in protection (Faurschou 2007, Schalka 2009, Kim 2010, Playtex 2007). For example, this means that someone who applies one-fourth as much sunscreen as in the SPF test gets just SPF 2.3 protection from an SPF 30 product. SPF 100 becomes just SPF 3.2.

How under-application of sunscreen cuts effective SPF
(based on applying one-fourth the recommended amounts)

SPF on label	Average SPF of users at (0.5 mg/cm2)	% UV transmission (amount reaching skin)
15	2	50%
30	2.3	43%
50	2.6	38%
100	3.2	31%