Fortune spoke with experts to understand the facts about sunscreen.
Basically, there are two varieties of sunscreen: physical and chemical. Physical, also known as mineral-based, contains two main active ingredients, zinc oxide and titanium dioxide, which act as a physical barrier between your skin and the sun. Sunscreens without these two active ingredients are classified as chemical, and usually contain a mix of other active ingredients.
Most of the concerns swirling about sunscreen involve the active ingredients in chemical sunscreens.
“The concern isn’t about them being chemical sunscreens per se, but about the fact that they are absorbed through the skin,” FDA press officer Cherie Duvall-Jones tells Fortune. “This means we need to know what these absorbed sunscreen ingredients do when they get in the human body. For example, can they lead to cancer or cause developmental or reproductive problems if people use sunscreens every day?”
That’s a question Emily Spilman, a safety scientist with the nonprofit Environmental Working Group (EWG), would like to see better answered. Based on her research into chemical ingredients in sunscreen, she’d like to see stricter regulations from the FDA.
“Some [active ingredients] are linked to skin allergies and immunotoxicity,” Spilman tells Fortune. “Some of them are also linked to more concerning impacts like hormone disruption, endocrine disruption.”
“Four studies published in 2020 support previous findings that oxybenzone can act as an endocrine disruptor and may increase the risk of breast cancer and endometriosis,” an EWG spokesperson tells Fortune. And while it’s not definitive that hormone disruptors will directly cause cancer, he says, “some common contaminants in sunscreens are also linked to carcinogenicity.” Carcinogens are substances either known to cause cancer or that may be linked to cancer.
“To date, none of the manufacturers of sunscreen active ingredients currently on the U.S. market have provided these data to the FDA,” Dr. Theresa Michele, Director of the FDA’s Office of Nonprescription Drugs, tells Fortune.
“Although the FDA does not have information indicating that currently marketed sunscreen active ingredients … have established safety risks, it’s important to determine whether or not there are risks with use of these ingredients,” Michele says. “This is why the agency has asked for the missing information on safety.”
“Trying to avoid endocrine-disrupting chemicals can be difficult as a consumer,” Spilman says. But it’s not impossible.
The safest bet is to use broad spectrum mineral-based sunscreen, Spilman says. You’ll know it’s mineral sunscreen if the only two active ingredients are zinc oxide and titanium dioxide, she notes.
Additionally, Spilman advises using a stick mineral sunscreen or one that’s cream-based, because aerosol (spray) sunscreens can pose yet another health threat if inhaled.
The academy also recommends reapplying sunscreen every two hours when outside, or after swimming or sweating. And remember that you need sunscreen even on cloudy days, as up to 80% of the sun’s UV rays can penetrate the clouds.
Despite some concerns about what’s in our sunscreen, the American Academy of Dermatology emphasizes the importance of wearing it.
In a statement to Fortune, the AAD added: “While recent studies have shown that some chemical sunscreen ingredients can be absorbed into the body through the skin, the data does not show that there are any effects on a person’s health. Those with concerns about chemical sunscreen ingredients can opt for a physical sunscreen.”
The FDA, EWG, and AAD all encourage people to wear sunscreen outside. While there’s no clear evidence that sunscreen products cause cancer, the evidence connecting UV rays to cancer is clear.
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