Mineral vs. chemical sunscreen: Is one safer?

Every year and every season brings about new wellness, fitness and beauty trends. You know, things like charcoal toothpaste, bioceramic infrared therapy pajamas and nonsurgical face-lifts.

For the last couple of years, all-natural or mineral sunscreens have been growing in popularity, and as summer approaches, your Facebook feed is sure to be full of suspiciously timely ads for what's supposedly a healthier version of conventional sunscreen.

Whether or not mineral sunscreen is safer or healthier than chemical sunscreen is a gray area (for now), but the Food and Drug Administration (FDA) is working to more tightly regulate the US sunscreen market and find out which ingredients in currently approved sunscreens, if any, are harmful to human health.

Chemical sunscreens tend to go on the skin easier, while mineral sunscreens are often difficult to rub in.

Sunscreens are divided into two major classes, Dr. Tyler Hollmig, director of dermatologic surgery at University of Texas Dell Medical School in Austin, tells CNET. They're either classified as chemical or physical, based on how they work.

Both classes have been shown to reduce short- and long-term damage to the skin, reduce the risk of sunburn and of skin cancer, Dr. Hollmig says: The only real difference, he points out, is how they do that.

"Chemical sunscreens act almost like a sponge, absorbing UV light, while physical sunscreens act more like a shield, deflecting the sun's rays," Dr. Hollmig explains.

Common ingredients in chemical -- or conventional -- sunscreens include oxybenzone, avobenzone, octisalate, octocrylene, homosalate, and octinoxate. Because of their makeup, chemical sunscreens tend to "be more elegant in terms of ease of application and minimizing that icky white residue," Dr. Hollmig says.

Physical (also called mineral) sunscreens, on the other hand, contain zinc oxide or titanium dioxide, and often feel sticky going on the skin.

You can absorb chemicals through your skin, but no dangerous ones are approved for use in the US.

Part of the reason mineral sunscreens have become so mainstream is that many people worry about their bodies absorbing the ingredients in chemical sunscreens. While it's possible you could absorb a small amount of mineral sunscreen, it's unlikely based on the way they work: They sit atop your skin and deflect the sun's rays, and are easily washed off with sweat or water.

It's a fair concern: Ingredients from certain sunscreens have been demonstrated to be absorbed and enter the bloodstream, although no data to date shows that any FDA-approved chemical sunscreens are harmful, Dr. Hollmig says.

Two ingredients can be harmful when absorbed through the skin (more on that below), but as of this writing, claims that approved chemical sunscreens are toxic or a hazard to human health have not been proven, says Dr. Hollmig.

So, while it's true that chemical sunscreen does indeed get absorbed by the body, more information is needed on what exactly the health implications are when this happens with currently approved sunscreen ingredients.

The FDA is working to gather more safety data about the extent to which our skin absorbs approved sunscreen ingredients and, most importantly, whether absorbing sunscreen has any effects on your skin or body. In February 2019, the FDA issued a proposed rule asking manufacturers to provide more data about the safety of certain sunscreen ingredients which have been used in the US for years.

In January 2020, the FDA released a brief about a clinical trial that looked at the absorption of sunscreens. The brief reports that "there is evidence that some sunscreen active ingredients may be absorbed. However, the fact that an ingredient is absorbed through the skin and into the body does not mean that the ingredient is unsafe, nor does the FDA seeking further information indicate such."

The FDA continues to advise that everyone use sunscreen to protect their skin.

There are 16 active ingredients found in sunscreens, including:

In the February 2019 proposed rule, the FDA proposed that only two of the above ingredients be classified as "generally recognized as safe and effective" (GRASE) -- zinc oxide and titanium dioxide, which are found in mineral sunscreens. As for the other 14, the FDA wants more data on the safety and effectiveness of 12 of them. And for the final two ingredients, theFDA proposes that they are labeled as not GRASE.

Those two ingredients are Para-aminobenzoic acid (PABA) and trolamine salicylate. The FDA evaluated those ingredients and concluded that "the risks associated with use of these active ingredients in sunscreen products outweigh their benefits."

For what it's worth, neither PABA nor trolamine salicylate are currently allowed in FDA-approved sunscreens.

"It's important to note that the FDA asking for more data does not mean the ingredients are unsafe," Dr. Hollmig says. "In fact, many dermatologists feel like the FDA is overly strict in regulating sunscreens in our country."

"Some fabulous sunscreens have been used for decades in Europe, and with a wonderful safety record, and yet these have never been approved in the US," he continues. The FDA regulates sunscreen as an over-the-counter drug, rather than a cosmetic product, which contributes to the stricter rules.

To sum up, aside from the two ingredients that are not approved for use in the US, we know that chemical sunscreen ingredients are absorbed, but we don't know exactly what happens when they're absorbed and how that ultimately affects our short-term or long-term health.

Either type of sunscreen will work to protect your skin.

Because the science is currently lacking, Dr. Hollmig doesn't recommend one type of sunscreen over the other -- if your concern is protecting your skin, either will work.

"Well, I am a dermatologist," Dr. Hollmig says, "so I have to first recommend avoiding the sun altogether, at least at peak hours. I'd probably have us all live in caves if I could!"

Since we can't all live in caves (and we need adequate vitamin D for good health, anyway), Dr. Hollmig offers some tips that go beyond the avoidance strategy, namely: sunproof clothing and accessories, such as broad-brimmed hats, and sunscreen, no matter which type.

In other words, either mineral or chemical sunscreen is far better than nothing when it comes to skin health.

"The known benefits of wearing a chemical sunscreen -- reduction in risk for skin cancer, reduction in sunburn, reduced skin aging -- absolutely outweigh the theoretical risks of absorption," Dr. Hollmig says, although he adds that further scientific study is a good idea.

"Still, it would be surprising if a strong link to health problems is found simply because sunscreen use has been so prevalent for so long," he says, "almost like finding out that, when it comes to safety, maybe seat belts aren't all they are cracked up to be!"

The bottom line: Wear protective clothing or any kind of sunscreen when you're going to be out in the sun for a while (but be sure to find a balance between protecting your skin and getting enough vitamin D).

If you have decision paralysis because of the mineral-versus-chemical debate, you might be overthinking it, Dr. Hollmig says: Regardless of the UV-blocking mechanism (physical or absorptive), you should look for a few key characteristics in sunscreens.

Sunscreens should be "broad-spectrum," Dr. Hollmig says, meaning they have UVA and UVB protection, with an SPF (sun protection factor) of 30 or higher, and are water-resistant.

"SPF refers to how well the product reduces penetration of UVB light, which causes sunburn and certain skin cancers," Dr. Hollmig explains. "UVA light is more difficult to block, but has been shown to contribute to skin aging and certain melanomas. The 'broad-spectrum' denotes a product that mitigates both UVA and UVB."

As for the SPF 30 specification, Dr.
Hollmig says it's recommended because SPF 15 blocks about 93% of UV light, while SPF 30 blocks 97%.

Sunscreens with an SPF above 30 really only have the potential to prevent an additional 3% of UV from being absorbed by the skin, which is typically not worth the high price tag of many of these products, Dr. Hollmig says.

"As a general rule, you don't have to break the bank to find a great sunscreen," Dr. Hollmig says. "More expensive products often feel better as they are applied to the skin, but this doesn't mean they are better at managing harmful UV rays. La Roche might feel more elegant, but Walmart can get the job done, too."

Whatever you buy, make sure to reapply throughout the day for optimal efficacy, Dr. Hollmig advises.

The information contained in this article is for educational and informational purposes only and is not intended as health or medical advice. Always consult a physician or other qualified health provider regarding any questions you may have about a medical condition or health objectives.

Read more:
Mineral vs. chemical sunscreens: How they work and which one is better - CNET