Hold Up: Sunscreen May Not Prevent Skin Cancer?

If more Americans than ever are wearing sunscreen, why has melanoma, the deadliest form of skin cancer, tripled among adults since the 1970s? And if that’s true, isn’t sunscreen one big hormone-disrupting, coral-reef-bleaching hoax that’s doing more harm than good? It’s time to level-set expectations on what sunscreen can and cannot do.

The days are getting longer, sun burning hotter and beaches filling up faster with bodies, bare-all. The good news is that more people than ever before are applying sunscreen. The weird news is that doesn’t seem to be changing skin cancer rates for the better — in fact, quite the opposite, the American Association of Dermatology reports that melanoma skin cancer, the most common cancer diagnosis in the United States, is on the rise, nearly tripling since the 70s.

So what gives?

Shouldn’t higher sunscreen use see lower skin cancer rates? Maybe it’s time to take a more honest look at sunscreen and re-evaluate our sun-worshipping cultural phenomenon.

The rise in skin cancer rates is, in part, because the tanning bed generation of the 80s and 90s has hit adulthood. No amount of sunscreen now is going to undo the damage of those 10-punch cards under ultra-violet-pumping lights. But the reasons, per usual, are also more complicated than teen choices, begging the question: How much do you really know about what sunscreen does? You see, there’s a common misconception, fueled by shady marketing and incorrect assumptions, that sunscreen blanketly prevents skin cancer. It doesn’t. Not 100-percent anyway. (1234)

First, There’s More Than One Kind of Skin Cancer

And it’s important to understand that we don’t fully get how skin cancer develops

Science has some pretty good ideas (hello, UV radiation and severe sunburns), but things like family history also play a role in whose at higher risk. Knowing just when and why accumulative damage tilts the scale toward cancer is still a relative unknown — as is why melanoma can surface in areas that rarely see sunlight.

Melanoma begins in the melanocytes (your bodies pigment-producing cells) and spreads, making it the most dangerous and deadly of the three primary types of skin cancer. The other two non-melanoma skin cancers, basal cell carcinoma and squamous cell carcinoma, are the most common forms but are easier to treat since they don’t usually spread. (567)

Second, Not All Sunscreens Are Created Equal

A quickie on physical vs. chemical sunscreens

Chemical sunscreens, sometimes also called organic sunscreens (because, yes, chemical compounds can be organic), tend to be the preferred consumer choice since they don’t leave a white tint. Some compounds work better than others against UVA or UVB rays, so most chemical sunscreens contain a mix of both, up to 20-something chemicals in a single formula.  Unfortunately, some such chemicals (ahem, looking at you oxybenzone) are known hormone-disruptor and coral-reef killers.

Physical sunscreens, sometimes called mineral sunscreens, rely on two minerals filters for their UV-defying power: zinc oxide and titanium dioxide. Although physical sunscreens tend to score higher marks on the safe-for-humans card that the FDA isn’t really keeping score on, there is some concern that both minerals in their the nanoparticle form pose unknown risks. (89)

Either Way, Cancer Prevention Claims Are a Stretch

The Environmental Working Group thinks they’re total hogwash

Probably because the FDA allows companies to claim cancer prevention and broad-spectrum protection without providing supporting evidence. Then again, it’s hard to conclusively demonstrate the solution to a problem that’s not fully understood. The EWG’s beef with cancer prevention claims are that they’re misleading because they overpromise by saying, essentially, that sunscreens can help prevent or lower the risk of something that science hasn’t definitely figured out yet (and that’s affected by a lot of factors outside of sunscreen’s control, like family history and skin tone). 

There’s no doubt that sunscreens protect against sunburn, which most experts agree is a contributing factor to the development of skin cancer…some skin cancers. The correlation between sunscreen application and melanoma, which kills nearly 20 Americans every day, is less certain. Some organizations present compelling numbers linking sunscreen use to a reduced risk of melanoma, but other studies directly contradict their data. But that hasn’t stopped the billion-dollar sunscreen industry from saying it (or at least implying it) by touting cancer prevention claims without distinguishing between melanoma and non-melanoma skin cancers or making clear that reducing risk isn’t the same as preventing cancer. (101112)

SPF Probably Doesn’t Mean What You Think it Means

Double the SPF offers only marginally better protection

Labels aside, the larger point is, no one thing or event causes skin cancer. What sunscreen does is help address one piece in the cumulative skin-cancer-causing puzzle: sunburns. SPF, or Sun Protection Factor, measures a sunscreen’s ability to prevent UVB from damaging the skin over time. For example, SPF 15 filters out about 93 percent of incoming UVB rays, whereas SPF 30 filters out 97 percent. That 4 percent difference can make a difference, especially if you’re more sun sensitive, but not double-the-strength level of difference. And no sunscreen can filter 100 percent of UVB rays. (1314)

Sunburn isn’t the End All of Sun Damage

UV radiation also produces free radicals

At this point, it’s worth remembering that SPF only measures UVB protection, or how long it takes to see a sunburn. UVA rays do plenty of damage without the tell-tell signs of red, tight, hot-to-the-touch skin. Even broad-spectrum sunscreen that protects against both UVB and UVA can’t protect against all sun damage, like the proliferation of free radicals that damage skin cells and lead to visible signs of aging. (15)

In Any Case, The Environmental Concerns Are Real

Both physical and chemical sunscreens put our oceans at risk

Unfortunately, several of the chemicals used as sun filters (namely oxybenzone and octinoxate) in chemical sunscreens are showing up in more than just the sunscreen: increasingly (and in several documented cases, alarmingly) they’re surfacing in our oceans. Over the last 20 years, massive coral bleaching has increased dramatically. Could your sunscreen be speeding up the process? The chemical compounds contained in sunscreens, the same chemical compounds known to disrupt hormones in humans, have reached detectable levels in seawater. And plenty of studies have demonstrated that even at low concentrations these chemicals are destructive to coral and other marine life. Moreover, at least one study predicts that at least 10 percent of the world’s coral reefs are directly at risk of harm due to ingredients in sunscreen washing off within 20 minutes of submersion. Some places, like Mexico, have already taken steps to ban certain sunscreens from vulnerable tourist-heavy eco-parks. (1617) So, should you skip the sunscreen? No, def not – but it’s worth being cognizant of the larger context of our purchasing power, and the greater ecosystem we call home! Ocean safe sunscreens are on the up and up and we’re starting to see a number of viable options on that front.   

Balance Your Sunscreen Use With Other Sun Protection Measures

And maybe check your eco-tourism footprint

By no means am I advocating that we abandon the use of sunscreen in our daily lives. The link between severe sunburns and skin cancer is evident and sunscreen does help protect from sunburn. It just might not be the end-all solution we thought it was, especially as doctors and scientists grapple with higher rates of skin cancer. There are other ways, in conjunction with proper sunscreen use, to protect your skin. And considering the impact our consumer choices have on the environment is also a noteworthy personal care consideration.

I’m not one to advocate a sedentary indoors-only lifestyle…but one of the most effective ways to lower your risk of skin cancer is to stay out of the sun. Not all day, mind you, but during peak hours when possible. I’m also not one to dictate a conservative dress code (hello California girl to the max), but layering up is another workaround to sun overdosing that can complement your sunscreen use. Oh, and maybe…. Just maybe… consider somewhere other than the beach for your next vacation? No one wants to miss out on the snorkeling adventure on their next tropical getaway, but it’s worth noting that more humans than ever are traveling to fragile ecosystems not exactly equipped for our collective footprint — or in this case, sunscreen print. I hear the Canadian Rockies get snow all year round…

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