There is nothing like feeling the warmth of summer sun on your skin—and soaking it up safely means applying sunscreen to protect ourselves from skin cancer.
But what about concerns that sunscreen itself could lead to other cancers, due to its chemical ingredients?
Fortune spoke with experts to understand how to best keep ourselves safe while enjoying sunlight.
What is in sunscreen?
Depending on the product, you'll find several active ingredients that provide broad spectrum protection against the sun's damaging UVA and UVB rays, according to the American Academy of Dermatology.
Basically, there are two varieties of sunscreen: physical and chemical. Physical, also known as mineral-based, contain 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.
Should you be concerned about your sunscreen?
The answer largely depends on what kind of sunscreen you’re using. Most of the concerns swirling in the sunscreen sphere are about the active ingredients in chemical sunscreens.
A 2020 randomized clinical trial of the U.S. Food and Drug Administration (FDA) found that six active ingredients (avobenzone, oxybenzone, octocrylene, homosalate, octisalate, and octinoxate) in various chemical sunscreens were systemically absorbed into the body.
“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 se more clearly answered. Based on her chemical sunscreen ingredients research, 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.”
Spilman pointed out that two ingredients in particular, octinoxate and oxybenzone, have been linked to disruption of the endocrine system, which creates and releases hormones for myriad important bodily functions.
Hormone disruptors and carcinogens
The terms "hormone disruption" and "endocrine disruption" have been thrown around as more research has emerged about humans exposure to chemicals. But do they really mean? The National Institute of Environmental Health Sciences calls endocrine disruptors “natural or man-made chemicals that may mimic or interfere with the body’s hormones” and are associated with various health problems, including some cancers.
“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, according to the Cleveland Clinic, are substances that may increase your risk of cancer.
Some of those ingredients to look out for—in addition to octinoxate and oxybenzone—are octocrylene, which the EWG says is often contaminated with benzophenone, a carcinogen. Aerosol sunscreens have also been found to be contaminated with benzene, another cancer causing chemical, the EWG says.
In 2019, the FDA requested data from the manufacturers of these chemicals to determine their safety.
“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.”
So, which sunscreen is safest to use?
“Trying to avoid endocrine-disrupting chemicals can be difficult as a consumer,” Spilman says.
But it’s not impossible.
Spilman says the safest bet is to use broad spectrum mineral-based sunscreen to avoid the potentially harmful active ingredients of chemical sunscreens. You’ll know it’s mineral sunscreen if the only two active ingredients are zinc oxide and titanium dioxide, she notes.
Within mineral sunscreens, Spilman also advises using cream-based lotions or sunscreen sticks; while zinc oxide and titanium dioxide do not absorb into the skin like chemical sunscreen, aerosol (spray) sunscreens can pose yet another health threat if inhaled.
“Because of the potential of exposure through inhalation, the International Agency for Research on Cancer has classified titanium dioxide as possibly causing cancer in humans,” EWG tells Fortune. “For this reason, powdered or spray formulations containing titanium dioxide are a concern.”
Spilman also recommends avoiding sunscreens that included "fragrances" on their inactive ingredients label. “That term can really hide the mixture of potentially harmful chemicals behind it,” she says.
Sunscreens made for young children, she adds, are perfectly fine for anyone to use, as they are usually formulated with higher safety standards.
In addition to following EWG’s sunscreen guidelines, consumers can follow the general advice of the American Academy of Dermatology by looking for products with:
- Broad-spectrum protection (protecting against both UVA and UVB rays)
- SPF 30 or higher
- Water resistance
The academy also recommends reapplying sunscreen every two hours when outside, or after swimming or sweating. And remember that even on cloudy days, you need sunscreen, as up to 80% of the sun’s UV rays can penetrate the clouds.
Bottom line: Yes, you should still wear sunscreen
While there are concerns about what’s in our sunscreen, the American Academy of Dermatology emphasizes the importance of wearing it.
“Skin cancer is the most common cancer in the U.S., and unprotected exposure to the sun’s harmful ultraviolet rays is a major risk factor for skin cancer,” the AAD stresses in its official sunscreen guidelines.
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 whenever they are outside. Because while the evidence remains unclear about whether or not these chemicals are linked to cancer, the evidence connecting UV rays to cancer is clear.
