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Regina Barber (3:50)

Michelle, so one big reason sunscreens differ so much in the US Compared to other countries has to do with, like, how we categorize the sunscreen. So what is that difference?

Michelle Wong (3:58)

Yeah, so in most places it's categorized as a cosmetic or a special cosmetic. But in the US And Australia, it's a drug, which means that the way it's produced is going to be held to a higher standard, it's going to be more consistent, there's more rules on how it can be produced, what ingredients can go into it. The ingredients need to be tested for things like safety, and you are getting a guaranteed efficacy.

Regina Barber (4:23)

So this means that, like, it's going to take longer to change in the US because it's going to go through those drug approvals and everything.

Michelle Wong (4:30)

Yeah, exactly. So in the US with any new drug ingredient, there's a huge process that needs to be gone through. It's got to go through a whole bunch of safety approvals. And in the US there's also a requirement for animal testing for these approvals, and that's generally the biggest sticking point. But that process can change. So in Australia, sunscreen is also a drug, and we get the newer sunscreen ingredients pretty quickly after the rest of the world, even though it is still technically a drug. And that's because drug approval processes aren't the same everywhere.

Regina Barber (5:02)

So like you said. Okay, it's been decades since the US Sunscreen has been updated. They tend to focus on protecting against UVB rays. But since then, there has been research that maybe we should also be protected from UVA Rays. So why is that important?

Michelle Wong (5:19)

Yeah, so even though UVA is lower energy and it does seem to cause less damage, in pretty much every respect, it does still cause damage. So there's research showing that it definitely contributes to melanoma. There's a lot of research, especially on sun tanning beds, which only put out uva. The reason they most of them put out only uva, some of them put out a combination of UVA and B. And that's because in the past it was thought that UVA was less damaging and maybe not damaging at all. And so people could get tanner without getting burnt and that associated skin damage. But later on it was found that tanning beds definitely contribute to melanoma. There's a statistic which is tanning beds are more strongly connected to skin cancer than smoking is to lung cancer. What?

Regina Barber (6:10)

Oh my gosh.

Michelle Wong (6:11)

Wow.

Regina Barber (6:11)

Okay, so let's talk about what broad spectrum protection actually means then. So like in the us, I use Olay like every, every day. It says UVA and UVB protection, but what does that actually mean? Like you said, the regulation for calling something broad spectrum is very different in the US versus other countries.

Michelle Wong (6:33)

Yeah. So there's two criteria for calling a sunscreen broad spectrum. One of them is one tenth of the UV absorbed needs to be longer wavelength than 370 nanometers. So that means the sunscreen needs to have a decent amount of protection at the really long UVA wavelengths that are so long they are almost violet. Basically, this is just to make sure the sunscreen does give decent protection against a broad range of wavelengths and not just the shorter ones, which was what was traditionally protected against with a sunscreen, the ones that are more linked to sunburn. Now the second criteria is that the UVA protection needs to be at least one third of the SPF.

Regina Barber (7:17)

Really?

Michelle Wong (7:17)

Yeah. So in the US they only need that 370 nanometer criteria. That's called the critical wavelength. But in Australia, the eu, the rest of the world, you need that plus you need that one third SPF rating.

Regina Barber (7:30)

I remember reading after, like SPF 30, you don't really need it. What do you have to say about like the different levels? Do they actually protect way more or is it negligible?

Michelle Wong (7:45)

So in theory, if you do the calculation, an SPF 30, if you apply it properly at 2 milligrams per square centimeter on your skin, that's going to only let through 1/30 of the UV coming in. So if you have an SPF 60, then that's going to only let in 1/60. Now if you do a bit of maths, 1/60 is half the amount of 1/30. So basically SPF 30 will let in twice as much UV as SPF 60. Now if you convert that to a percentage that's going to be really tiny, like 1/30 is 3%. So it's like a tiny amount coming in. But that only works if you're applying it perfectly with a massive amount, which most people don't got it. So the higher the spf, the better it is if you don't apply enough. If you apply perfectly, then pretty much SPF 30 and above, it's going to be pretty equal.

Regina Barber (8:36)

You're good to go. Okay, let's dive into the chemistry. Let's dive into your expertise. What kind of ingredients are like we talking about in non US Countries that are allowed in sunscreen versus like what.

Michelle Wong (8:49)

We have here in the us there's only about, I think, eight commonly used UV filters. So the two, there's two that are classified as, I guess, physical or mineral. There's zinc oxide and titanium dioxide. They're allowed pretty much everywhere around the world. The other type are called chemical, I guess in quotation marks because everything is a chemical. And these ones are carbon based. They tend to be molecules that have lots and lots of benzene rings so they can absorb uv. The structures look very similar to what we see in like dyes, so dyes that dye clothes, except dyes will be absorbing visible light. These ones are tailored to absorb uv and there are tons of these, but there's only a handful allowed in the US which are a bit older. And they tend to absorb more of those shorter wavelengths against burning. The newer ones tend to absorb more of the longer wavelengths going into uva, getting closer to visible. And yeah, those are the ones that aren't allowed in the U.S. yes.

Regina Barber (9:55)

So the FDA hasn't approved these new ingredients. And when people hear that maybe they think they aren't safe. Can you talk about how researchers think about safe versus not safe with these new filters?

Michelle Wong (10:07)

Yeah. So these newer ingredients are purposely designed so that they are meant to be inherently safer. And what that means is they have a larger structure, they have particular chemical properties that make them less likely to go through skin and cause any sort of, I guess, systemic whole body effect. The other way of testing safety is trying to see how much goes into the body, where it ends up interacting with the body, what sorts of effects it might have. And there's a lot of ways of doing this the traditional way was by doing animal testing. So you put a whole bunch of sunscreen on rats or on mice. But there are newer methods where instead of just putting as much as you can on an animal until something happens, you can test on things like cells, receptors. There are things like what are called organs on chips. And from that you can work out what's safe kind of replacing these animal studies, which, I mean, scientists are always trying to replace them because they're expensive and they're not as ethical as some other alternatives. But at the moment, the FDA still requires the animal studies, which has been the big hurdle with getting these approved. Because in places like Europe, animal testing is banned for cosmetics and because sunscreen happens to be a cosmetic in Europe, that's been the big stumbling block.

Regina Barber (11:26)

Do you have any idea when or hope when it might have an update to the list of new ingredients for sunscreens in the U.S. i try to.

Michelle Wong (11:35)

Have hope, but at the same time, I have been hoping for this for the last 15 years or so. And there's always been predictions about when it's going to happen, like it's going to be next year, it's going to be next year. So in theory, it might be next year, but in reality, I guess we'll see.

Regina Barber (11:54)

Are there any ingredients that are bad or dangerous to look out for in any sunscreens in the world?

Michelle Wong (12:00)

Not really. I guess the biggest risk is always with uncontrolled impurities. But in any well regulated marketplace, sunscreen should be one of the safest things that you can put on your skin. I guess the other big thing is really looking at the instructions and making sure you follow the instructions. I think most people generally do less than the instructions. Most people put on less sunscreen than they should. But as long as you're not putting on a ridiculous amount of sunscreen or eating it or inhaling a lot, then it's generally one of the best tested skincare ingredients you'll ever put on your skin.

Regina Barber (12:34)

Recently on social media, I've seen younger people have a lot of fear about sunscreen and question its effectiveness. How do you, as somebody who is on YouTube, who is a science communicator, how do you respond to that?

Michelle Wong (12:50)

I'd say if you look at all the people freaking out about sunscreen safety, a lot of the time when they're talking to you, they're referring to animal studies. But then if you look at the things that are positive about sunscreen, it's always in people, like there's been a clinical trial that's found that sunscreen has halved the risk of several types of skin cancers. It completely halted skin aging for the period of the trial. And then you see case studies like, you know, 92 year old woman has been wearing sunscreen for 60 years and her face looks really good, but her neck where she didn't apply sunscreen is a lot more aged. So I think that really demonstrates that a lot of the risks of sunscreen, the safety issues, those are mostly theoretical. And the advantages are actually things that you see in humans. There's never really been someone who's had a massive health effect because of sunscreen, apart from things like allergic reactions.

Regina Barber (13:44)

While we in the US Are waiting for maybe sunscreen to be updated, how can people protect themselves?

Michelle Wong (13:50)

I mean, the older sunscreens still work very well. The main thing is not applying enough. The proper amount is you should be putting 1 teaspoon on each limb, 1 teaspoon for the front of your body, 1 teaspoon for the back of your body, and 1 teaspoon for your head plus neck, plus ears. For your face alone, it should be a quarter teaspoon. You also want to reapply. Generally, the recommendation is every two hours. And also after you go in the water or if you towel off after swimming, that's another big, big issue. Also, don't let it heat up massively. If it does, then you should probably buy a new sunscreen or if you leave it in a hot car. Yeah, that's one of the biggest things. And the other thing in terms of protecting your skin from the sun, sunscreen is one of the most fiddly, error prone options. Like we just don't apply enough. We have to reapply. You don't have to worry about that if you're putting on, let's say, a UV protective shirt or a hat. I think at the end of the day, the best sunscreen you can wear is the one that you enjoy, one that you can apply a lot of regularly.

Regina Barber (14:56)

Michelle, thank you so much for talking to us today.

Michelle Wong (14:59)

Thank you for having me.

Regina Barber (15:01)

This episode was Produced by Burleigh McCoy, edited by showrunner Rebecca Ramirez, and fact checked by Tyler Jones. Jay Siz was the audio engineer. Beth Donovan is our senior director, and Colin Campbell is our senior vice president of podcasting strategy. I'm Regina Barber. Thank you for listening to Short Wave from npr.

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