FDA approves a well-known sunscreen ingredient—finally

The FDA approved the first new sunscreen ingredient in over 20 years—one that's long been used around the world. What took so long?

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:02Flora 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 bemetrazinol, also known as B E M T. And this is a big deal because it's the first new sunscreen ingredient approved in the U.S. in over two decades. Meanwhile, skin cancer has become the most common cancer in the U.S. Here to get into the chemistry of sunblock is A.J. Adey, a chemistry PhD candidate studying sunscreen at UCLA. She's also the founder of Sula Labs, which tests sunscreen and other cosmetics formulations. A.J., welcome to Science Friday.

• 0:42Speaker 01

  Thank you for having me. I'm excited to chat.

• 0:45Flora Lichtman?

  Me too. Is this approval big news in your world?

• 0:49Speaker 01

  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.

• 1:01Flora Lichtman?

  Well, how is bemetrazinol different from other sunscreen ingredients?

• 1:05Speaker 01

  Yeah, so B E M T 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 in organic UV filters. So that would be zinc oxide and titanium dioxide. And then there are organic UV filters, and those are ones like homosilate, octisilate, oxybenzone, avabenzone. So B E M T 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.

• 1:45Flora Lichtman?

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

• 1:51Speaker 01

  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.

• 2:11Flora Lichtman?

  Say more.

• 2:13Speaker 01

  Yeah, 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 it's exciting because typically you have to combine several different UV filters and 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.

• 2:54Speaker 01

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

• 3:13Flora Lichtman?

  And what's the difference between UVA and UVB light?

• 3:16Speaker 01

  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.

• 3:30Flora Lichtman?

  You know, there's some concern about the chemicals in sunscreen. Is BEMT any safer or is its chemistry any different?

• 3:40Speaker 01

  Yeah, 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, you know, 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, you know, toxicity risk profile is significantly lower than you would, than one would expect.

• 4:22Flora Lichtman?

  You mentioned that the EMT doesn't leave as much of that white cast on the skin. What gives sunscreen that white color?

• 4:32Speaker 01

  So, you know, that, that can be kind of a deterrent for a lot of people for 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, those are inherently pigments as well.

• 5:15Speaker 01

  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.

• 5:23Flora Lichtman?

  I love your gusto for this, this subject.

• 5:27Speaker 01

  Yeah, I mean, I, like you said, I'm a PhD candidate and, you know, this is my, my field of work. So, thank you.

• 5:35Flora Lichtman?

  This is your actual thesis?

• 5:37Speaker 01

  Yeah, quite literally, sunscreen, white cast, biological interactions. Like, this is, I could go on forever.

• 5:47Flora Lichtman?

  That's really fascinating. Thank you, AJ.

• 5:49Speaker 01

  No problem. Thank you for having me.

• 5:52Flora Lichtman?

  AJ Adey, a chemistry PhD candidate studying sunscreen at UCLA.

• 6:03Flora Lichtman?

  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 Scuturo, who's been following sunscreen formulations and regulation for years and most recently wrote about it for KFF News. Michael, thanks for being here.

• 6:33Speaker 02

  Thanks for having me.

• 6:34Flora Lichtman?

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

• 6:38Speaker 02

  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 like a Walgreens or a CVS. And those are things that have to go through traditionally an animal testing process.

• 7:21Speaker 02

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

• 7:56Flora Lichtman?

  Why is sunscreen regulated like a drug?

• 8:00Speaker 02

  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

• 8:18Speaker 02

  That some of these drugs don't cause reproductive harm, or that they have a low level of toxicity in the body.

• 8:26Flora Lichtman?

  I mean, we put a lot of things on our body every day, like lotion and cosmetics. So does the rationale go beyond that?

• 8:35Speaker 02

  Well, 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 over cautious. And I think that in this case, they might be over correcting.

• 9:10Flora Lichtman?

  At the same time, I mean, there, there is this sort of anti-sunscreen movement in the US right now with their skepticism around the safety of sunscreen. How does this story fit in with that?

• 9:22Speaker 02

  I think the sunscreen controversy kind of started in 2019, around then, because the FDA did tests, did tests on several sunscreen ingredients that have been sold for, 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, they reclassified these drugs as, and it's very complicated, not gross, so it's like 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.

• 10:06Speaker 02

  They were not necessarily saying they're not safe. They were just saying, we would like more data because we don't really know. And it.

• 10:15Speaker 02

  And it made people really wonder like, well, can they trust these things? So there were, there were about 12 chemicals that were, that were in this, that were moved into this not CROSS, 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 sunscreen. So it's just to say, it's very complicated. The FDA, they've let these, 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.

• 10:52Flora Lichtman?

  Okay. That's what I needed.

• 10:54Speaker 02

  And that's very confusing.

• 10:55Flora Lichtman?

  It is a gray area.

• 10:57Speaker 02

  Right. And I'll, and I'll say this, like, if you look at like this, like this, I'm in Germany right now and I purchased the sunscreen and on the front of the packaging of this sunscreen says like, it says, this is free of microplastic, it's free of octanocite, it doesn't have homosali because it's no longer used in Europe. So the, 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 CROSS. But I think everyone kind of agrees that BEMT, the new chemical, is very safe. It's the most vetted sunscreen ingredient. It has more safety data than zinc oxide and titanium dioxide. So it's a very safe ingredient.

• 11:39Flora Lichtman?

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

• 11:43Speaker 02

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

• 11:53Flora Lichtman?

  Latest October. Okay. Michael, thank you so much for joining me today.

• 11:57Speaker 02

  Thank you so much.

• 11:59Flora Lichtman?

  Michael Scuturo is a health journalist based in New York City. This episode was produced by Shoshana Buxbaum with help from Charles Berquist. If you can't get enough of Science Friday, check out our newsletter, sciencefriday.com/newsletters. I'm Flora Lixman. We'll catch you next time.