Sunscreen Can End Up in Your Bloodstream—But You Shouldn’t Stop Using It
According to a new study, sunscreen creams and sprays don’t just sit on top of your skin—some of the ingredients get absorbed into your bloodstream.
While more studies are warranted about what exactly this means, the harmful effects of UV damage from the sun are well documented, and adequate sunscreen use can help prevent melanomas and other skin cancers.
However, sunscreen doesn’t necessarily have to be your only measure of sun protection. Wearing more sun-protective clothing, opting for a wide-brimmed hat, avoiding direct sun in the peak hours, and choosing shadier spots to ride are all ways to prevent against UV ray exposure.
Even during the winter in the upper part of the country, the sun is still a factor when you’re out for a ride, especially on those rare-but-glorious days when short sleeves come into play. No matter where you live, though, outdoor riding means exposure to UV rays—even if it’s a cloudy day—and the need to stay protected. The obvious answer? Sunscreen.
Sunscreen is regularly touted as one of the top ways to block the sun’s harmful rays, but a new study suggests those creams and sprays don’t just sit on top of your skin—some of the ingredients get absorbed into your bloodstream.
Published in the medical journal JAMA, the research looked at six common sunscreen active ingredients: avobenzone, oxybenzone, octocrylene, homosalate, octisalate, and octinoxate.
In a randomized clinical trial done over a 21-day period with 48 participants, researchers examined absorption levels of four sunscreen products—including lotion, aerosol spray, non-aerosol spray, and pump spray. No matter which type of product was being used, participants applied the sunscreen to 75 percent of their body surface area, with varying rates of reapplication for four days. Blood samples were collected both during the sunscreen usage and for over two weeks afterward.
Their findings? All six active ingredients were absorbed into the bloodstream of participants, even without regular reapplication.
Sunscreen is not the only topical formula to do this, according to Trevan Fischer, M.D., a surgical oncologist at John Wayne Cancer Institute at Providence Saint John’s Health Center in Santa Monica, California. He told Runner’s World that the porous nature of the skin allows ingredients to “sink in” all the time, with everything from anti-aging serums to moisturizers. The reason an Epsom salt bath works to get magnesium in your system, for instance, is because it soaks in through the skin.
But when are those ingredients considered harmful? That’s a tricky question. For example, the sunscreen researchers acknowledged that the study does have some limitations, which are its setting and usage. Participants were indoors—rather than in the sun—and they used a maximum amount of sunscreen. That means they didn’t experience the kind of sweating that can lead to some or most of the sunscreen “washing off” as a result.
Also, previous research has noted that many people don’t tend to apply the recommended amount of sunscreen, and they don’t reapply it as often as dermatologists would like. The American Academy of Dermatology’s guidelines are as follows:
Apply enough sunscreen to cover all exposed skin. Most adults need about 1 ounce—or enough to fill a shot glass—to fully cover their body.
Don’t forget to apply to the tops of your feet, your neck, your ears, and the top of your head.
Apply sunscreen to dry skin 15 minutes before going outdoors.
Apply a lip balm or lipstick that contains sunscreen with an SPF of 30 or higher.
When outdoors, reapply sunscreen approximately every two hours, or after swimming or sweating, according to the directions on the bottle.
But even with a few caveats, the study is useful for setting a direction for future research, in which more long-term effects can be studied, according to Fischer.
Fischer said he’s heard concerns about sunscreen ingredients from patients before, and a study like this might lead some to believe that sunscreen is best avoided.
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However, he said, that’s the wrong conclusion. Even the researchers of the recent study emphasized that people should not stop using sunscreen simply because of these results, Fischer pointed out.
“The ingredients covered by this research have been in sunscreen for decades at this point,” he said. “While more studies are warranted, the fact remains that the harmful effects of UV damage from the sun are well documented, and there is significant concern about the higher risk of melanomas and other skin cancers without adequate sun protection.”
But that doesn’t mean sunscreen needs to be your only measure, he added—especially if you’re concerned about the ingredients. Instead, it can be part of a larger strategy. Jessie Cheung, M.D., a board-certified dermatologist in Chicago, recommends physical UV blockers like zinc over chemical options. These are commonly in sunscreen powders like Brush on Block. Fischer also recommends wearing more sun-protective clothing, opting for a wide-brimmed hat, avoiding direct sun in the peak hours between 10 a.m. and 4 p.m., and choosing a shady spot instead of one where you risk a blistering sunburn.
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