Sunscreen chemicals soak into your bloodstream, study finds

Sunscreen Photo by Shutterstock/Africa Studio

As a kid at the cottage, stepping outside involved the elaborate process of having your mom lather you in thick, white sunscreen—the worst part was having to wait until it soaked in before jumping in the lake. But you knew it was the right thing to do. It was protecting your skin against those cancer-causing sun rays. A new study conducted by the FDA in the United States, however, brings into question the chemicals used in sunscreens.

The FDA tested 24 healthy participants in a laboratory between July and August 2018. Participants were randomly given a type of sunscreen: spray, lotion, or cream, and told to apply two milligrams of sunscreen for every 1cm2, covering 75 per cent of the participant’s body. They applied the sunscreen four times a day for four days with 30 samples of blood collected over seven days.

The study found that four chemicals commonly found in sunscreen, avobenzone, oxybenzone, octocrylene, and ecamsule, are absorbed into your bloodstream after being applied. The fact that sunscreens are systemically absorbed, however, has been known since as early as 1977, says Richard Langley, a professor of dermatology and the director of research in the dermatology division at Dalhousie University.

What was new about this study was that “[researchers] were able to measure plasma concentrations of [the] four active ingredients in sunscreens to be more than .5 nanograms per millilitre. And the significance of that is that’s higher than the FDA approved…optimal toxic levels for sunscreen radiance,” Langley says.

Now, before you start dumping your supply of photoprotective sprays and lotions, Langley wants people to understand that this study has not proven that the use of sunscreen causes any negative effects. “What this study really told me is that I would not recommend people stop using sunscreen,” he says. “I think that further research is required to evaluate this and see what the true absorption rate is under real circumstances, and to understand what the risk of the absorption of some of these chemicals really is.”

From Langley’s perspective, the study had a few methodological errors. First, it was conducted in a laboratory rather than outdoors where people would typically wear sunscreen. “People are out sweating in the sun; how does the sun affect it? And people who are swimming at the cottage. How do all these impact the reality?”

Second, Langley says it’s unrealistic that people would apply this much sunscreen during a day. “I’ve never put sunscreen on 75 per cent of my body because what I do is I wear sun protective clothing,” he says. “I’m not going to put it in areas that are protected by clothing. That is a method of protecting yourself.” Langley also pointed out that the study only looked at adults, whereas children are known to have higher absorption rates.

While the effects of sunscreen chemicals absorbed systemically is still unknown, UV rays are a known carcinogenic that cause skin cancer. “It’s been classified by the World Health Organization. It’s ultraviolet radiation.” According to Langley, skin cancer is the most common form of cancer in Canada, occurring 85 per cent of the time in the neck and head areas.

To protect against this, the FDA’s 2019 guidelines recommend using sunscreen that contains zinc oxide and titanium dioxide, two chemical compounds that reflect UV rays. Langley says there are also other methods of protecting yourself against the sun. “We recommend staying in the shade [and] wearing protective clothing…Also important is what time of day are you out? We recommend minimizing exposure during the peak UV exposure [hours], 11 to 3. But also to know what the UV index is. You can check with Environment Canada.”

While the FDA study does raise a number of questions about the chemicals in sunscreen, Langley is adamant that he will not stop recommending sunscreen to patients. Instead, he hopes this will motivate researchers and manufacturers to take a closer look at the effects of sunscreen. “I don’t think there’s any cause for alarm here. I think this is definitely an important study. It’s going to help us understand that we need further information not just on the benefits of sunscreen but on the risks.”

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