SProtecting yourself from sunburns, skin cancer, and other dangerous effects of UV rays is important with unscreen. However, certain sunscreen chemicals (or filters) have recently come under intense scrutiny for potential health risks and impacts on the environment. Most of the concern centers on ingredients in chemical sunscreens—like oxybenzone, avobenzone, octocrylene, homosalate, octisalate, and octinoxate—which absorb ultraviolet (UV) rays.
Physical, or mineral, sunscreens—which only include zinc oxide and titanium dioxide as active ingredients—are less of a safety concern for human health, since they block UV rays by sitting on top of the skin and deflecting them.
It is also possible that sunscreen chemicals such as oxybenzone or other sunscreen chemicals could cause coral bleaching, damage to aquatic animals and even death when they get into the water.
A report published Aug. 9 by the National Academies of Sciences, Engineering, and Medicine concludes that while people should continue to use sunscreen—and, indeed, use more of it more often—additional research is needed into several safety aspects of its active ingredients.
Here’s what the report says about sunscreen and what it means for human and environmental health.
Underused sunscreen
Only about a third of people in the U.S. regularly use sunscreen, the report finds, although about 70 to 80% of Americans do use it when they’re at the beach. However, most sunscreen users don’t slather on enough—the American Academy of Dermatology advises using one ounce to cover the whole body—and often don’t reapply every two hours, as is recommended. People of color are less likely to develop skin cancer but have higher rates than their white counterparts.
Learn More: The Safest Sunscreens to Buy—and Which Ingredients to Avoid
The best evidence available—obtained through large randomized controlled trials and longitudinal observational studies—shows that broad-spectrum sunscreen (meaning that it protects against both UVA and UVB rays) with an SPF higher than 30 reduces the risk of skin cancer, sunburn, and aging caused by sun exposure. Sunscreen should always be combined with other preventative measures, including wearing sunscreen when it is hot and looking for shade.
There’s not enough research on safety
There have been no toxic effects that scientists found in sunscreen on people. However, the report authors state that further studies are necessary to determine safety. In 2019, and 2020, studies done by the U.S. Food and Drug Administration found that sunscreens can penetrate the skin and remain there for many days. While this doesn’t necessarily mean that the chemicals are dangerous, some were found in the body in concentrations higher than the upper thresholds set by the FDA, beyond which safety studies should be conducted. Three weeks after their application, the levels of oxybenzone (both UV-absorbing chemicals) and homosalate were higher than that in a study. Concerns about the effects of UV filters on hormones and gene expression have been raised in animal research. The report’s authors also point out several gaps in human safety research; for instance, safety studies have not followed people over long periods of time, which means they can’t look at potential outcomes that may appear over time, such as cardiometabolic risk, risk of cancer, or fertility problems.
The authors concluded that overall, scientific evidence supports sunscreen use. There are encouraging signs in scientific reviews that UV filters can be safely used by humans. The reviews have not concluded that concentrated levels of UV filters harm male or female fertility, female reproductive hormone levels, fetal growth, or children’s neurodevelopment. “To date, no levels of toxic effects have been found in humans that outweigh the benefits of these filters in reducing overexposure to [ultraviolet rays],” the authors write. “However, the authors all recognize substantial data gaps.”
More research is needed to understand the impact on other species.
The authors state that while scientists have studied how sunscreen chemicals impact certain animals and plants, there are no data for corals. They argue that there needs to be more testing of sunscreen ingredients’ toxicity levels in different sea creatures, especially in places that may be more vulnerable to exposure. These include coral reefs in shallow areas near places where humans do a lot of recreational activity, like swimming; in slow-moving freshwater environments where there’s also a lot of recreation; or in places that are exposed to wastewater.
Sunscreen in action
According to the authors, scientists must learn more about real-world environmental effects of sunscreen chemicals. For instance, while some UV filters (including avobenzone, dioxybenzone, and octocrylene) have been shown to take a long time to biodegrade when they’re tested in labs, researchers should test how they accumulate in nature, such as by sampling organisms and the soil, the authors write.
A second priority is to study how sunscreen chemicals end up in our environment and interact with natural stressors, such as pollution or climate change. Scientists believe that more needs to be done on how ecosystems react when they are subjected to multiple types of stress, and what happens when sunscreen chemicals combine with other dangers, like rising temperatures or contaminants.
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