Mineral vs. chemical sunscreen: What’s best for protecting your skin?

Browsing the sunscreen aisle at the pharmacy can be overwhelming. Gone are the days of tanning oil and only a few brands of sun protection to choose from. Consumers–especailly shoppers in European and Asian countries–have a wide variety of options now. In the United States, there are two different types of sunscreen filters available. They are colloquially called mineral and chemical sunscreen based on how they work. 

What is a mineral sunscreen?

The active ingredients in mineral sunscreens are zinc oxide and titanium dioxide. They work by physically reflecting the sun’s rays. 

“They’re the typical sunscreens you think about from movies in the 80s, where you have the really white nose,” Dr. Abigail Waldman, a dermatological surgeon at Brigham and Women’s Hospital in Boston tells Popular Science “That’s like the zinc oxide look, but they’ve made mineral sunscreens to be much more cosmetically appealing since then.”

Mineral sunscreen still might appear a little more white on the skin and be more difficult to rub in, but they are typically more gentle on the skin. Mineral sunscreens also start working very quickly after being put on the skin. They can be a great choice if you have sensitive skin or if you want something more natural and generally safe for coral reefs. These types of sunscreens also protect the skin against both UVA and UVB rays.

“UVB causes burns and more often causes skin cancer, but UVA causes tanning and the longer term signs of aging, like wrinkles and hyperpigmentation, discoloration, things like that,” explains Waldman. 

[ Related: Do I really need to wear sunscreen every day? We asked dermatologists. ]

What is a chemical sunscreen?

Chemical sunscreens are usually more transparent or clear than some mineral sunscreens.

They by absorbing UV light instead of reflecting it. The energy from the light is converted into heat and released from the skin. 

“These sunscreens absorb UV light and then basically dissipate it as heat. And they have slightly different properties,” Dr. Sameer G. Gupta, a dermatological surgeon at Massachusetts Eye and Ear Hospital in Boston, tells Popular Science. “The most important is that there’s broad spectrum coverage. Broad spectrum UV coverage means it covers both UVA and UVB rays.”

A broad spectrum chemical sunscreen will protect against the different wavelengths of UV light and is why these types of sunscreen typically have three or four active ingredients on the label. 

Chemical sunscreens also tend to be more likely to cause a rash or sensitivity 

“Some people who say that they hate sunscreen are usually referring to a chemical sunscreen, because it can be a little irritating. Sometimes it can burn your eyes a little bit, depending on how sensitive your skin is,” says Waldman.

Chemical sunscreens are also more likely to damage coral reefs and other sea life. According to NOAA, some of the chemicals found in some sunscreens that can harm marine life include: Oxybenzone, Benzophenone-1, Benzophenone-8, OD-PABA, 4-Methylbenzylidene camphor, 3-Benzylidene camphor, nano-Titanium dioxide, nano-Zinc oxide, Octinoxate, Octocrylene 

Chemical sunscreens are still effective when used correctly and there are several varieties to choose from. It is best to apply a chemical sunscreen at least 15 minutes before going out in the sun since it takes extra time to absorb than a mineral sunscreen does. 

[ Related: What makes a sunscreen ‘reef-safe’? ]

Does sunscreen itself cause cancer?

According to both Gupta and Waldman, the answer is a resounding no. 

“There is absolutely no evidence that sunscreen itself causes skin cancer,” says Dr. Gupta. “It’s very much the opposite. There’s very clear evidence that it can help protect against skin cancer, such as squamous cell carcinoma.”

Some of the confusion on this point is due to a few studies published in 2020 saying that the chemicals in chemical sunscreen are being absorbed by the skin and can show up in the blood. 

“I think that caused a lot of suspicion around chemical sunscreens,” says Dr. Waldman. “You are eating more of your skincare than you’d like to admit. We’re constantly touching our faces, putting our hands or our mouth, touching our food. So it’s hard to say that it’s [sunscreen] actually being absorbed or if we’re just ingesting a lot of the stuff we put on our skin and hair. To me, those studies didn’t really change how I thought about anything because of how much skincare we eat.”

What is the best sunscreen?

“The best sunscreen is one that you’re willing to apply and reapply,” says Dr. Gupta. “You should try to find one that you really like and are willing to reapply with broad spectrum coverage.”

That broad spectrum protection against both UVA and UVB rays and consistent reapplication is crucial. Both mineral and chemical sunscreen will lose potency over time due to sweating, swimming, and general sloughing off of the skin. 

“If you were out in the sun, your sunscreen has basically just turned into moisturizer after two hours,” says Dr. Waldman. “It still has some effect after two hours. It’s just probably not what the SPF says on the bottle.”

This story is the second in a series of stories on sunscreen and part of Popular Science’s Ask Us Anything series, where we answer your most outlandish, mind-burning questions, from the ordinary to the off-the-wall. Have something you’ve always wanted to know? Ask us.

 

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