The Sunscreen Myth: Could It Really Cause Skin Cancer? | Antiviral

bBecause of his work as a dermatologist, Dr. Deshan Sebaratnam regularly receives questions from friends, family and strangers about skin treatments. But lately, he says, he’s been confronted with “a lot of myths around sunscreens,” especially on his social media feed.

One of the most common is “that sunscreen can actually cause skin cancer,” says Sebaratnam, an associate professor at UNSW.

Chemist Dr. Michelle Wong says the myth largely stems from concerns about benzene, a contaminant (not an ingredient) found in some sunscreens and other products such as disinfectants and dry shampoos. leading to product recalls in 2022.

What does the evidence say about benzene?

“Although it is a known carcinogen, the risk of cancer actually depends on the amount you are exposed to,” says Wong.

The amount of benzene found in the recalled consumer products was minuscule, 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, said calculated that 10 ml of contaminated sunscreen would – in the worst case – result in absorbing 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 penetrate the skin easily – only about 1% is absorbed. The main route of exposure is inhalation.”

A 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, fear continues to be spread on social media about benzenes in sunscreen and the risk of cancer.

“Australia is the skin cancer capital of the world,” says Sebaratnam. “Every six hours, an Australian dies from melanoma. Skin cancer is one of the most preventable cancers and there is excellent evidence from many scientific studies that sun protection, including sunscreen, helps minimize this risk.”

Wong, who 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 that it’s benzene-free is probably impossible, honestly, given how ubiquitous it is everywhere, because there are probably at least a few molecules in sunscreen exposed to the air,” she says.

So should I wear sunscreen?

Sunscreen, when used properly, has “never led to anything other than a significant reduction in skin cancer rates,” says Prof. David Whiteman, medical epidemiologist and cancer control expert at the QIMR Berghofer Medical Research Institute.

Despite this, he says he is often asked about the higher rate of skin cancer among sunscreen users.

“The sunscreen doesn’t cause the cancer,” says Whiteman.

“It’s like people who wear body armor are more likely to die from a gunshot wound. That’s because you only wear a bulletproof vest when you enter a place where you could be shot, and sometimes you just get shot in a place that isn’t protected by the bulletproof vest. The same goes for sunscreen.

“People don’t put on sunscreen when they go to the cinema at nine o’clock in the evening. People only apply sunscreen when they go out in the sun. So there is a direct link between the use of sunscreen and exposure to the hazard.”

Prof. Anne Cust, chair of the Cancer Council’s national skin cancer committee, says drug regulator the Therapeutic Goods Administration is taking “a very conservative approach to setting limits for benzene.”

“These limits are based on the potential health consequences of an individual using the maximum recommended amount of a product containing 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 risks, she said.

“Australians should have confidence in the efficacy and safety of approved sunscreens they use.”

One myth she would like to see debunked is that the SPF in cosmetic products such as makeup provides sufficient protection against UV exposure. In reality, most cosmetic products don’t provide enough protection, so Cust says it’s advisable to wear extra sunscreen with SPF50 or SPF50+ under makeup.

“Sunscreen should be applied 20 minutes before going outside, and for an adult, the recommended application of sunscreen is approximately one teaspoon for each arm, leg, front of the body, back of the body and face, including neck and ears,” she says.

“Sunscreen should be reapplied at least every two hours, regardless of the water resistance of the sunscreen, and should be reapplied after swimming, exercising, sweating and drying with a towel.”

• Melissa Davey is the medical editor of Guardian Australia. She has completed a master’s degree in public health and moonlighting as a fitness instructor

• Antiviral is a biweekly column that interrogates the evidence behind health headlines and fact-checks popular wellness claims