Sunscreen: The SPF Myth

The sunscreen business is a 1.3-billion-dollar business fueled by dermatologic dogma and consumer concerns about the dangers of the sun. According to the market research group Datamonitor Consumer, profits are expected to increase by 6.5 percent by 2017. Much of that growth can be attributed to the development of high SPF products that tend to have a higher price point. A 2007 Environmental Working Group analysis found that more than 1 in 7 products makes claims of SPF values higher than 50+. Not too long ago, SPFs of 30 were considered state of the art, now it’s not unusual to find products touting numbers as high as 70 or more.

While it may seem like sunscreens with higher SPF ratings would provide more benefits, that may not be the case. Using an SPF 80 improves protection over an SPF 30 by a mere 1.75 percent. Even doubling SPF potency will only deliver slightly more protection; an SPF 50 sunscreen blocks 98 percent of sunburn rays while an SPF 100 blocks 99 percent.

Some health care professionals are also concerned that high-SPF products may tempt people to stay in the sun too long. Though sunscreens suppress sunburns, an important indicator of overexposure to the sun, long exposure still increase the risk of other kinds of skin damage and skin cancers that may show up later in life. In an article published in the August, 1999 edition of the Journal of the National Cancer Institute, Philippe Autier, a former World Health organization scientist, found that “use of higher SPF sunscreen seems to increase the duration of recreational sun exposure of young white Europeans”. Dr. Autier further claims that high-SPF products spur “profound changes in sun behavior” that may account for the increased melanoma risk found in some studies.

SPF is a multiplication metric that measures time spent in the sun without causing erythema (skin redness). For example, if you ordinarily get red in 20 minutes without a sunscreen, wearing an SPF of 15 will allow you to stay out in the sun for 15 x 20 minutes or 300 minutes (6 hours). That means, if you wear an SPF of 45, you can now stay out in the sun for 18 hours! Unless your tanning in Alaska, the sun isn’t even out that long!

Because sunscreen ingredients are potentially toxic and higher SPF creams and lotions require more sun-filtering chemistry than their lower SPF counterparts, there are more health risks, including possible hormone disruption and allergic reactions. Perhaps this is why the FDA has proposed prohibiting the sale of sunscreens with SPF values higher than “50+”, stating that higher SPF may be “misleading to the consumer,” given that there is an “absence of data demonstrating additional clinical benefit” and that “there is no assurance that the specific values themselves are in fact truthful…”

Finally, it's not just how long the sun's rays get blocked, it also matters what type of rays they are. Ultraviolet radiation is streamed to Earth in three forms: UvA, UvB and UvC. While SPF measures a particular product’s potency for blocking UvB, which is associated with burning, it tells nothing about its effects on UvA and UvC. This omission can be a significant. UvA rays cause skin to age and accounts for most cases of squamous cell cancer. UvC rays, while ordinarily filtered out by atmospheric gases, may possibly be able to “reach live skin tissue and could produce erythema and possibly other undocumented effects…” particularly in wounded or abraded skin, according to Dr. George Chabot of the Health Physics Society, a non-profit radiation safety research organization.

When it comes to sunscreens, the bottom line is more is not always better. If you really want to protect your skin from the solar radiation, use sun sense. Apply only enough sunscreen to assure that you don’t cause erythema. Use a low SPF product and reapply as needed. Rinse it off when you don’t need it. And don’t stay in the sun long enough to burn.