FDA approves a well-known sunscreen ingredient—finally

[AUDIO LOGO] FLORA LICHTMAN: Hey, it’s Flora. And you’re listening to Science Friday.

The FDA recently approved a sunscreen ingredient that’s been used in Europe and Asia for years. It’s called bemotrizinol, also known as BEMT. And this is a big deal because it’s the first new sunscreen ingredient approved in the US in over two decades. Meanwhile, skin cancer has become the most common cancer in the US.

Here to get into the chemistry of sunblock is AJ Addae, a chemistry PhD candidate studying sunscreen at UCLA. She’s also the founder of SULA LABS, which tests sunscreen and other cosmetics formulations. AJ, welcome to Science Friday.

AJ ADDAE: Thank you for having me. I’m excited to chat.

FLORA LICHTMAN: Me, too. Is this approval big news in your world?

AJ ADDAE: Oh, for sure. I think over two decades, as you said, has been the last time that there’s been a UV filter approval in the United States. So this fundamentally changes the landscape a bit.

FLORA LICHTMAN: Well, how is bemotrizinol different from other sunscreen ingredients?

AJ ADDAE: So BEMT is actually the first UV filter that has been approved that is an organic UV filter that is generally recognized as safe and effective. So I say organic very intentionally because there are two UV filter classes that are allowed in the United States, inorganic UV filters– so that would be zinc oxide and titanium dioxide– and then there are organic UV filters. And those are ones like homosalate, octisalate, oxybenzone, avobenzone. So BEMT would fall under the organic class. And it would be the first and only one that contains this Generally Recognized as Safe and Effective status.

FLORA LICHTMAN: Does this new ingredient feel different, look different, go on differently?

AJ ADDAE: So it definitely has an advantage over zinc oxide and titanium dioxide in that it goes on the skin a little bit more transparently than you would expect from inorganic filters. So that’s a great advantage. But I would say the biggest advantage is actually in how efficiently it protects the skin from harmful UV damage.

FLORA LICHTMAN: Say more.

AJ ADDAE: So there are a lot of UV filters already allowed in the United States. But a lot of them really skew towards UVB protection, which is useful because sun protection factor really narrowly measures the ability for a sunscreen to protect you from UVB rays.

What’s great about BEMT is that it actually very efficiently absorbs both UVB and UVA rays, which would make it more of a broad-spectrum filter. And that’s exciting because typically, you have to combine several different UV filters in sunscreens to get a broad-spectrum claim, whereas with BEMT, you can do so a little bit more efficiently without taking up so much of the sunscreen’s real estate.

Now, the only other UV filter that does absorb broad spectrum is avobenzone, allowed in the United States. But the thing about avobenzone is that it does require other UV filters to stabilize it. So this is really the most efficient UV filter as far as that.

FLORA LICHTMAN: And what’s the difference between UVA and UVB light?

AJ ADDAE: So UVB light particularly, I think, we associate more with sunburn, whereas UVA light we associate more with photoaging, skin darkening, more of those cosmetic concerns that you see.

FLORA LICHTMAN: There’s some concern about the chemicals in sunscreen. Is BEMT any safer, or is its chemistry any different?

AJ ADDAE: To pass any UV filter in the United States, it requires a lot of toxicological evidence. And it requires evidence of understanding how a filter could interact with human biology.

What’s great about BEMT is that it’s actually a lot larger of a molecule than other UV filters that we’ve seen. And so it’s well beyond a limit that one would be concerned for extreme biological absorption profiles or exposure that could be harmful to the human skin or human body. So that’s also a really great advantage because the toxicity risk profile is significantly lower than you would– than one would expect.

FLORA LICHTMAN: You mentioned that BEMT doesn’t leave as much of that white cast on the skin. What gives sunscreen that white color?

AJ ADDAE: So that can be a deterrent for a lot of people wearing sunscreens. It all comes down to light scattering. Any color that we can see is a consequence of something reflecting visible light. And so what’s really great about zinc oxide and titanium dioxide is that they can absorb UV. But they also scatter light in such a way that we can see the color white.

And that also can be caused by aggregation and agglomerates of the zinc oxide and titanium dioxide minerals/particles in such a way that larger aggregates scatter more visible light. Those are inherently pigments as well. That’s why we see zinc oxide and titanium dioxide also in paints and coatings. And they just so happen to also absorb UV really well.

FLORA LICHTMAN: I love your gusto for this subject.

AJ ADDAE: [LAUGHING]

Like you said, I’m a PhD candidate. And this is my field of work. So thank you.

FLORA LICHTMAN: This is your actual thesis?

AJ ADDAE: Yeah, quite literally– sunscreen, white casts, biological interactions. I could go on forever.

[LAUGHING]

FLORA LICHTMAN: [LAUGHING]

It’s really fascinating. Thank you, AJ.

AJ ADDAE: No problem. Thank you for having me.

FLORA LICHTMAN: AJ Addae, a chemistry PhD candidate studying sunscreen at UCLA.

Given the benefits of BEMT and that it’s been used across the world for many, many years, why didn’t the FDA approve it sooner? And what does this sunscreen tale tell us about FDA approvals and how our system for regulating drugs works? Here with some answers is health journalist Michael Scaturro, who’s been following sunscreen formulations and regulation for years and most recently wrote about it for KFF News. Michael, thanks for being here.

MICHAEL SCATURRO: Thanks for having me.

FLORA LICHTMAN: So why did it take so long to get this ingredient approved?

MICHAEL SCATURRO: I think the main reason is that it’s expensive to bring a new drug through the FDA because in the United States, sunscreen chemicals are considered over-the-counter drugs. In France or in Korea or in many places around the world, sunscreens and sunscreen chemicals are considered cosmetics. And so they don’t really have to be subjected to animal tests.

But in the US, the FDA defines sunscreen as an OTC, an over-the-counter drug, which is kind of like aspirin or cough syrup or anything that you might buy at a Walgreens or CVS. And those are things that have to go through, traditionally, an animal testing process.

So DSM, the company that manufactures this chemical, had to submit that data. And so that’s hard because it’s very expensive. It costs them about $18 million to bring this new chemical through the FDA. And Congress has tried in two laws now to nudge the FDA in the direction of alternative testing methods. And they’re not quite convinced because for this new-ish, this new for us in the US, but widely used globally, this BEMT was still subjected to animal tests.

FLORA LICHTMAN: Why is sunscreen regulated like a drug?

MICHAEL SCATURRO: That’s a good question. I think it’s because the FDA is concerned about the potential toxicity of a product that people use every day. People are putting a lot of this on their bodies. And I think their position would be that they have to really be certain that some of these drugs don’t cause reproductive harm or that they have a low level of toxicity in the body.

FLORA LICHTMAN: We put a lot of things on our body every day, like lotion and cosmetics. So does the rationale go beyond that?

MICHAEL SCATURRO: So in writing about this over the last two years, I kept hearing that the FDA is very proud of its record in the 1960s of having been one of the only regulators globally to have prevented thalidomide from being sold in the US. That’s the drug that caused egregious harm to fetuses in many countries and led to people being born with birth defects. And so they have always been very, very overcautious. And I think that in this case, they might be overcorrecting.

FLORA LICHTMAN: At the same time, there is this anti-sunscreen movement in the US right now where there’s skepticism around the safety of sunscreen. How does this story fit in with that?

MICHAEL SCATURRO: I think the sunscreen controversy started in 2019, around then, because the FDA did test– did tests on several sunscreen ingredients that have been sold for a while have been considered to be safe to be in sunscreens. But they basically found that in some certain chemicals– were appearing in very, very small amounts in the human bloodstream. And I think they reclassified these drugs as, and it’s very complicated, not GRASE. So it’s Not Generally Recognized as Safe and Effective for use in sunscreens.

So it’s a really complicated way of saying that they needed more data to know whether these chemicals were safe. They were not necessarily saying they’re not safe. They were just saying, we would more data because we don’t really know. And it made people really wonder, well, can they trust these things?

So there were about 12 chemicals that were in this– that were moved into this not GRASE– so not considered– Not Generally Recognized as Safe and Effective– for use in sunscreens category. But the industry has begun to– has over the last few years phased out those chemicals. But essentially, four are still widely used in sunscreens.

So it’s just to say it’s very complicated. The FDA– they’ve let these chemicals exist in a kind of gray area because they said, again, they’re not generally recognized as safe and effective for use in sunscreens. But you can still use them.

FLORA LICHTMAN: That’s what I mean.

MICHAEL SCATURRO: And that’s very confusing.

FLORA LICHTMAN: It is a gray area.

MICHAEL SCATURRO: Right. And I’ll say this. If you look at this– I’m in Germany right now. And I purchased this sunscreen. And on the front of the packaging of this sunscreen– says– it says, this is free of microplastic, it’s free of octinoxate. It doesn’t have homosalate because it’s no longer used in Europe.

So the European companies are starting to market the fact that they no longer use some of these chemicals that in the US are considered not GRASE. But I think everyone agrees that BEMT, the new chemical, is very safe. It’s the most vetted sunscreen ingredients. It has more safety data than zinc oxide, and then titanium dioxide. So it’s a very safe ingredient.

FLORA LICHTMAN: When will we see the first BEMT sunscreens on the shelves here?

MICHAEL SCATURRO: So DSM, the company that manufactures this chemical, says that we can expect these drugs to be on store shelves in maybe latest October.

FLORA LICHTMAN: Latest October? OK. Michael, thank you so much for joining me today.

MICHAEL SCATURRO: Thank you so much.

FLORA LICHTMAN: Michael Scaturro is a health journalist based in New York City.

This episode was produced by Shoshannah Buxbaum with help from Charles Bergquist. If you can’t get enough of Science Friday, check out our newsletter, sciencefriday.com/newsletters. I’m Flora Lichtman. We’ll catch you next time.

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