Sunscreen chemicals can show up in your blood, according to a new study, but experts say there’s no reason to throw away your bottle.
Researchers with the U.S. Food and Drug Administration (FDA) conducted a small study of 23 people who applied sunscreen to 75 per cent of their bodies four times a day over four days.
The results, published in the Journal of the American Medical Association, showed four chemicals in the participants’ blood: avobenzone, oxybenzone, octocrylene, and ecamsule.
These were all present at levels at which FDA guidelines call for further safety testing.
What this means for your health is unclear.
“The clinical effect of plasma concentrations exceeding 0.5 ng/mL is unknown,” the study authors write.
“Yes, this is important because it makes us aware of the fact that there is systemic absorption of these ingredients, but further work needs to be done,” said Dr. Cheryl Rosen, head of dermatology at Toronto Western Hospital.
Evidence that sunscreens can be absorbed into the body has been around since at least 1997, according to an editorial linked to the FDA study. A 2008 study found a sunscreen chemical, benzophenone-3, in urine samples.
Dr. Sunil Kalia, an assistant professor of dermatology at the University of British Columbia, said that he wasn’t surprised to see that some sunscreen was absorbed. “What we don’t know is, does this cause any endocrine effect or does it cause any reproductive effect? And there’s no data yet showing that,” he said.
“Whereas, we know with sunscreen, that it does prevent skin cancer.”
Around 7,200 Canadians were diagnosed with melanoma, a form of skin cancer, in 2017, according to statistics from the Canadian Cancer Society.
Rosen notes that people have used sunscreen for decades, without many indications that it is causing harm. “We haven’t seen a clinical sign that there’s a problem from them.”
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A 2018 Health Canada investigation into sunscreen, after reports of skin reactions like burns, found no serious safety issues with the products and the department continues to recommend using sunscreen.
The FDA, while it also still recommends sunscreen, is encouraging more research into some of the chemicals used in the product. Earlier this year, the agency introduced a proposed rule that asked sunscreen manufacturers for additional safety data on some of the chemicals commonly used in sunscreen, a move that environmental advocacy groups like the Environmental Working Group — which has long called for more attention to sunscreen — applauded.
“Since the FDA began regulating sunscreens in the 1970s, the agency’s understanding of drug absorption through the skin and the ability to measure drug absorption have advanced; at the same time, the use of sunscreens has increased,” the agency wrote in a blog post on its website. “In the 1970s, sunscreens were used primarily on a seasonal basis to prevent sunburn, which is different from the frequent, daily use seen today.”
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Further research should test the effects of sunscreen on the way people actually use it, Rosen said. Most people don’t use the recommended amount, they sweat it off, they go swimming, and they don’t reapply as often as recommended. This particular study looked at the “maximal use” — which most people don’t even come close to, she said.
The study authors and these two dermatologists agree: you shouldn’t stop using sunscreen because of this study.
“These results do not indicate that individuals should refrain from the use of sunscreen,” the authors wrote.
Kalia frequently recommends mineral sunscreens containing zinc oxide or titanium dioxide to his patients, and both these ingredients are labelled “generally accepted as safe” by the FDA. Rosen warns that they aren’t always as effective as chemical sunscreen though, and some people find they leave an unappealing white cast on the skin.
The best way to protect yourself from the sun is to avoid it, Kalia said. Don’t spend time in the sun during the middle of the day when the sun is most intense, and if you are outside, try to stay in the shade, he said.
“But then sometimes that’s not possible,” he said. “That’s where we say, fine, you use protective clothing.”
Sunscreen is really the last step in sun protection, he said.
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