BBecause of his work as a dermatologist, Dr. Deshan Sebaratnam often gets questions from friends, family and strangers about skin treatments. But lately, he says, he’s been confronted with “a lot of myths surrounding sunscreens,” especially on his social media feed.
One of the most common is “that sunscreen can actually cause skin cancer,” says Sebaratnam, a joint associate professor at UNSW.
Chemist Dr Michelle Wong says the myth stems mainly from concerns about benzene, a contaminant (not an ingredient) found in some sunscreens and other products such as disinfectants and dry shampoo, which led to product recalls in 2022.
What does the evidence say about benzene?
“While it’s a known carcinogen, the likelihood of actually forming cancer depends on the amount you’re exposed to,” says Wong.
The amount of benzene found in the recalled consumer products was small, with the highest levels (six parts per million, or 6 ppm) reported in a sunscreen tested by Valisure.
Even then, Martyn Smith, a professor of toxicology at the University of California, calculate that 10ml Contaminated sunscreen would – in the worst case – absorb the amount of benzene people are exposed to by breathing city air for half a day.
“Benzene is a common air pollutant, an additive to gasoline, and is produced by gas stoves,” says Wong. “Benzene does not easily penetrate the skin – only about 1% is absorbed. The main route of exposure is inhalation.”
One group of dermatologists found sunscreen users actually had lower blood benzene concentrations compared to those who said they never used sunscreen, suggesting that gasoline emissions and secondhand smoke have a greater impact.
Despite this, fearmongering about benzene in sunscreen and cancer risk continues to be spread on social media.
“Australia is the skin cancer capital of the world,” says Sebaratnam. “An Australian dies of melanoma every six hours. Skin cancer is one of the most preventable cancers and there is excellent evidence from many scientific studies that sun protection, including sunscreen, helps reduce this risk.”
Wong, which helps dispel misinformation about cosmetic products her Lab Muffin websitesays she’s seen some brands promote their products as “benzene-free” even though no brand intentionally adds the contaminant.
“Claiming it’s benzene-free is honestly probably impossible given how ubiquitous it is everywhere, since there’s probably at least a few molecules in any sunscreen that’s exposed to air,” she says.
So should I wear sunscreen?
Sunscreen, when used appropriately, “has never resulted in anything other than a significant decrease in skin cancer rates,” says Prof David Whiteman, a medical epidemiologist and cancer control expert at the QIMR Berghofer Medical Research Institute.
Despite this, he says he is often asked about higher rates of skin cancer found among sunscreen users.
“The sunscreen doesn’t cause the cancer,” says Whiteman.
“It’s like people wearing bulletproof vests are more likely to die from a gunshot wound. This is because you only wear a bulletproof vest when you go into a place where you might be shot, and sometimes you just get shot in a place that is not protected by the bulletproof vest. It’s the same with sunscreen.
“People don’t put sunscreen on when they go to the theater at nine o’clock at night. People only put sunscreen on when they go out in the sun. So there is a direct link between using sunscreen and being exposed to the hazard.”
Prof Anne Cust, chairman of Cancer Council’s National Skin Cancer Committee, says drug regulator the Therapeutic Goods Administration is using “a very conservative approach to setting limits for benzene”.
“These limits are based on the potential health impacts to an individual of using the maximum recommended amount of a product that contains more than two parts per million of benzene every day for 70 years,” she says. Products are being recalled out of an abundance of caution, and not because of significant risk, she says.
“Australians need to feel confident in the effectiveness and safety of approved sunscreens they use.”
A myth she would like to see dispelled is that the SPF in cosmetic products such as make-up will provide enough protection against UV exposure. In reality, most cosmetic products don’t offer enough protection, so Cust says it’s recommended to wear an additional sunscreen that’s SPF50 or SPF50+ under makeup.
“Sunscreen should be applied 20 minutes before going outdoors, and for an adult, the recommended sunscreen application is about one teaspoon for each arm, leg, front of body, back of body and face, including neck and ears,” she says.
“Sunscreen must be reapplied at least every two hours, regardless of the water resistance of the sunscreen, and must be reapplied after swimming, sports, sweating and towel drying.”
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Melissa Davey is Guardian Australia’s medical editor. She completed a master’s in public health and moonlights as a fitness instructor
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Antiviral is a bi-weekly column that interrogates the evidence behind the health headlines and checks out popular wellness claims
