Medical Examiner

Don’t Abandon Sunscreen Just Yet

People aren’t good enough at applying sunscreen for us to worry about the harms of its use.

A woman squeezing sunscreen into her hand.
boophotography/iStock/Getty Images Plus

Last week Outside magazine published a surprising piece from Rowan Jacobson, “Is Sunscreen the New Margarine?” Jacobson argues against the use of sunscreen on roughly the following premise: We are too quick to give weight to the damages of the sun’s rays (namely, skin cancer), and not cognizant enough of the benefits of sunlight (lower blood pressure, triggering of dopamine and serotonin), but the benefits are so numerous and beneficial they outweigh the possible harms. Anyone who slathers or sprays the protectant on their skin risks a Vitamin D deficiency, and the slew of problems that come along with that. Ultimately, sunscreen may turn out to be like margarine—long marketed as something healthy that we later realize actually kills us sooner. Margarine is actually the milder comparison Jacobson makes: “Slavish application of SPF 50 might be as bad for you as Marlboro 100s,” writes Jacobson. Yikes!

My main problem with this thesis is that it ignores one underrated truth: People are bad at applying sunscreen. Really bad. I know because over three years of my reporting career, I spent a considerable chunk of energy learning about the benefits of sunscreen, finding sunscreens that felt nice to wear on faces and skin and lips, and as is a hazard of the product reviewer gig, sharing my home with a giant endless supply of the stuff.

The truth is it’s all but impossible to be so diligent about sunscreen application that you’ll block all rays and all Vitamin D. Even applied perfectly every day, SPF 30 blocks only 97 percent of the sun’s UV radiation (and none of the light that reaches your eyes and combats seasonal affective disorder). To get that protection, you have to put on a lot of the stuff. Sunscreens are granted their SPF ratings based on 2 milligrams of lotion or spray applied to each square centimeter of skin.* In layperson’s terms: enough that you feel uncomfortably greasy. It’s also hard to do; a handful of studies suggest people put on one-quarter to half as much as they would need to get the rating on the bottle.

Sprays are particularly hard to apply liberally. In an experiment I did in my bathroom—some of the weirdest time I have logged on the clock at work—I sprayed sunscreen under lightly windy conditions, provided by a box fan, on a piece of tinfoil. Holding the bottle a few inches away, I lost half to the breeze. Plus, after applying once, you have to frequently re-apply if you’re spending time out in the sun, swimming, or sweating that sunscreen away. From personal experience I can confirm that this is simply hard to keep up with, even given the best of intentions.

All of this ends up meaning that even sunscreen-adherents end up spending a non-negligible amount of their time outdoors uncovered, allowing Vitamin D in. And the amount of sun exposure you need to get Vitamin D is actually pretty minimal: Experts advocating sun exposure as the best way to absorb the vitamin say that you should spend on the order of 10 to 30 minutes three times a week with your arms and legs exposed during midday in the summer for ideal exposure (it’s impossible to give an exact amount, as that will vary by location and skin tone, and yes, as Jacobson notes, it seems possible this recommendation is geared toward light-skinned folks). But even considering that a low estimate, it’s an extremely easy level of exposure if you’re spending a day outside—even if you wear sunscreen.

Jacobson takes pains throughout his piece to acknowledge that his thesis is supported by a new, small line of research that is regarded with skepticism within the dermatology community, which is all the more reason not to take the piece as advice on how to live your daily life, at least not yet. But it’s not clear that some of the main pieces of evidence for this rogue take are even correct. For example, he strangely evokes the health of “our ancestors” who “lived outdoors in tropical regions and ran around half naked” without noting the improvements in lifespan since, despite that being an incredibly relevant factor to cancer incidence.

Some of the more rigorous research seems like weak support, too. The most jarring piece of evidence he provides is a study claiming a lack of sun exposure is a risk factor on par with smoking cigarettes. The study surveyed 30,000 women over two decades and found that—in Jacobson’s words—“sun avoiders were twice as likely to die as sun worshippers.” But the study doesn’t mention asking participants about their sunscreen habits, so it’s possible that those longer-living beachgoers were basking on towels and lathering up. It’s also tricky to discern the lines of correlation here; the researchers didn’t control for other factors, writing, “it is not possible to differentiate between active sun exposure habits and a healthy lifestyle.” It’s at least possible that the uptick in lifespan for sun worshippers was simply the result of another correlated factor—perhaps healthy habits like exercise and vacations away from stress brought them into the sun in the first place.

Jacobson’s article does contain an important truth: Sunscreen isn’t a one-size-fits-all prescription. You could be forgiven for thinking it is from reading the American Academy of Dermatology’s recommendations, and even some articles of mine. Cosmetic companies and scientific research alike have long overlooked people of color—who, Jacobson points out, have much lower rates of melanoma than white people. That means they may need longer in the sun, or even no sunscreen, to get the Vitamin D they need. And any individual might be more or less at risk for skin cancer or afflictions attributed to a lack of Vitamin D. (It’s also true that any one person might also be a lot more type A at following application directions than I will ever have patience for.)

It’s always hard for a journalist or the sunscreen industry to tell you what your particular needs are. Even after comparing sunscreen to smokes, Jacobson lands on this point, too, while noting that after completing the piece, he’s going into the outdoors “if not half naked, then reasonably close.”

If you’re concerned about your Vitamin D levels, your doctor can tell you what they are with a blood test. If they’re low, you might want to choose to lighten up on the lotion (though, as even Jacobson re-affirms, sunburns pose a big cancer risk and ought to be avoided if possible). Or if you’re like me, you might be interested in applying face sunscreen for entirely different reasons—to help keep wrinkles at bay, or to protect your skin after doing face masks with ingredients that make it both glowier and even more sensitive to rays. And in my experience, err on the side of more sunscreen than you think you need.

*Correction, Jan. 14, 2019: An earlier version of this story misstated the amount of sunscreen you must apply. It is 2 milligrams per square centimeter of skin, not 2 grams.