Sunscreen: Could It Be Toxic??

9:31Prof. Rachel Neale:Right. Yeah. So to get to the bottom of this, I want to tell you about these couple of FDA studies that came out right before the pandemic. And they did what are called maximum usage trials, where they bring people into the lab and over multiple days, they slather sunscreen like all over their bodies. Sounds fun. It's like my dream. Here's Brandon.

9:52Dr. Brandon Adler:So sunscreen was applied to 75 % of the body surface area. If you look at a chart of what that means, that is a lot of your body. That's essentially everywhere besides maybe your bikini zone.

10:07Dr. Adewole Adamson:How many weeks were they getting that sunscreen on for? Four or five days total in the lab. And then what did the researchers do next?

10:13Prof. Rachel Neale:So then they measured their blood throughout that study. but also 21 days afterward. And they looked to see, like, how much of this chemical was showing up in the blood. And we did see oxybenzone there. And it was in a high enough level that it passed this FDA threshold. And this is something that people online really love to point out.

10:38Dr. Brandon Adler:Now, it's very easy for this to lead to headlines, right? Sunscreens are absorbed into the body. and then you very, very quickly get words like toxic and dangerous to get thrown out.

10:51Dr. Adewole Adamson:I mean, yeah, it doesn't sound great. That's the, yeah, that our body is absorbing these and 21 days later they're found in our blood at all. I don't love. I know, it's kind of icky. And then at some increased threshold level, obviously our scientist friend doesn't sound concerned.

11:17Prof. Rachel Neale:Oh, so like those FDA studies, that threshold was very misleading. People kind of took that and ran with it and said like, hey, look, sunscreen is toxic. Yeah, yeah. But the threshold in those studies didn't actually suggest danger at all. In fact, the FDA concluded that study, quote, these findings do not indicate that individuals should refrain from the use of sunscreen.

11:41Dr. Adewole Adamson:So if they were at very high levels, toxic, dangerous levels, what would you start to see?

11:49Prof. Rachel Neale:Yeah, so I found this systematic review of around 30 studies. And they looked at studies that are trying to find out, does oxybenzone actually affect our hormone levels? And what they concluded was that there's no clear evidence in the literature that oxybenzone actually harms us.

12:09Dr. Adewole Adamson:Uh-huh. So it looks like at the doses that most people are getting their sunscreen at, we don't need to worry here. Exactly. Yeah. And what about the coral reef? People are very worried about the coral reef. Your sunscreen is killing the coral reefs.

12:27Dr. Brandon Adler:Oxybenzone, which has been known to bleach our coral reefs.

12:30Dr. Adewole Adamson:It can damage coral reefs and wildlife, so you don't want to do that. So do I need to worry about that? Yeah.

12:36Prof. Rachel Neale:So oxybenzone is one of those chemicals that has been banned in places like Hawaii. Uh-huh. Because they're worried about their coral reefs. Yeah, they're worried about their coral and the bleaching. Uh-huh. When you take a closer look at these studies, the science is also a bit more nuanced. Like, scientists would bring young coral into the lab and then expose them to these sunscreen chemicals and find that it was toxic to their DNA. It caused coral bleaching. But when you look in a real world setting and actually measure the amount of this stuff that's floating around in the ocean, we don't see it in nearly as high scary levels.

13:16Prof. Rachel Neale:It's all about the dose.

13:18Dr. Adewole Adamson:Yes. It's all about the dose. Whether you're talking about the coral, whether you're talking about the people.

13:23Dr. Brandon Adler:We know beyond a shadow of a doubt that the primary cause of coral bleaching is climate change. Right. That's been shown now. It has been suggested by more realistic and moderate studies that sunscreen exposure, especially oxybenzone, may add what they call insult to injury. But it's certainly not the primary cause of the decimation of coral reefs that we've been seeing.

13:48Dr. Adewole Adamson:Guys, it's climate change.

13:50Prof. Rachel Neale:But despite that, all of these studies did lead to some changes. A bunch of manufacturers have taken out this chemical oxybenzone from their sunscreens anyway. because people just weren't buying them from the shelf anymore.

14:04Dr. Adewole Adamson:Oh, okay. Because consumers didn't want it. And so what are they putting in the sunscreen these days? Should we be worried about that?

14:10Prof. Rachel Neale:Well, here's the thing. People are worried about all the other ingredients that come in sunscreens. There's a bunch of other chemicals that also showed up in these same studies. But the story is pretty much the same. Like they do get into our blood, but we have no evidence that they hurt us. And as someone who has dug into the research, Brandon isn't worried about them.

14:35Dr. Brandon Adler:I have chemical sunscreens on my face right now. I was outside this morning in the early morning sun, and I applied chemical sunscreens. So I personally do not believe that there is a significant risk with routine use of these ingredients. And he said chemical sunscreen. Aren't all sunscreens chemical sunscreens?

14:59Prof. Rachel Neale:So they can break down into like two major pools. There's chemical sunscreens and then there's mineral sunscreens. Oh, yes.

15:08Dr. Adewole Adamson:I have heard this. Sounds like marketing fluff. No, mineral sunscreens are legit. Are they really? What is the difference? It's like it's all a chemical. But mineral sounds, you know, like a nicer chemical you'd get at a spa.

15:26Prof. Rachel Neale:Yeah. I mean, it's a little, to get a bit nerdier, the chemical sunscreens have organic molecules in them, and the mineral sunscreens have inorganic ones. These are things like zinc oxide.

15:39Dr. Adewole Adamson:So by organic chemical, just because I don't want the audience thinking that means it doesn't have pesticides in it, you mean it's carbon-based?

15:46Prof. Rachel Neale:Yeah.

15:47Dr. Adewole Adamson:Okay, and then inorganic, like zinc oxide, no carbon in there.

15:52Prof. Rachel Neale:And are they better? So the people who are maybe still freaked out about the fact that chemical sunscreens get into your blood at all, mineral sunscreens are the other option because they more so like sit on the surface of your skin and they don't go down into your blood in the same way as those chemical sunscreen ingredients.

16:13Dr. Adewole Adamson:However, they are more likely to give you a white cast. They leave a white cast on your skin. Uh-huh. And then these DIY sunscreens that people are making, I mean, do they work?

16:29Prof. Rachel Neale:Yeah, I was curious about that too. So I asked Brandon.

16:32Dr. Brandon Adler:And what I'm seeing more and more is that whenever an ingredient or a product gets called toxic, the next sentence is, let me sell you a non-toxic alternative. And this is when we get into homemade recipes for sunscreens that we're finding on the internet. People are turning to making their own sunscreens with zinc oxide and beef tallow.

16:57Dr. Adewole Adamson:How are they getting their zinc oxide from sunscreen? Is this like the Simpsons? You made a spoon out of a bigger spoon? I got to process that for a second.

17:05Prof. Rachel Neale:You made a spoon out of a bigger spoon. I guess they're buying the mineral.

17:12Dr. Adewole Adamson:Like you took sunscreen and then made a different sunscreen out of it. They just added beef tallow to the sunscreen you bought at the store.

17:19Prof. Rachel Neale:I actually found one study that looked into these kind of online recipes. What they did was find 15 recipes from online and they whipped them up in the lab and then tested them out. Oh, and what did they find? It turns out a few of them didn't even have anything in them that could act as a sunscreen. and then the rest were less than an SPF of 6. Uh-huh, which is unlikely to help you. It's not going to help you, yeah.

17:48Dr. Brandon Adler:When people have looked at how effective these homemade sunscreens are, they really aren't at all.

17:55Dr. Adewole Adamson:So don't DIY your sunscreen. No shockers there.

17:59Prof. Rachel Neale:For those of us in the U.S., there is some sunscreen news. There was this chemical sunscreen ingredient that was recently approved. It's called Bemotrisanol. And it's the first sunscreen ingredient that we've gotten approved in like 20 years.

18:13Dr. Adewole Adamson:Wow.

18:15Prof. Rachel Neale:Good job.

18:16Dr. Adewole Adamson:Good work, guys. It's been in Australia for a while, this ingredient, and Europe. But why are people getting excited about it?

18:24Prof. Rachel Neale:Yeah, so I talked to Brandon about it, and he says it has a lot going for it.

18:28Dr. Brandon Adler:I would say the U.S. is just barely catching up. So Bemotrisanol does a great job being a true broad-spectrum sunscreen ingredient. It is very stable and mixable with other sunscreen ingredients, which is a real plus here. And in addition, bimetrizinol is a large molecule that is not easily absorbed into the skin or into the body.

18:53Dr. Adewole Adamson:Mm-hmm. So, okay. So, it doesn't get absorbed too much. So, it's kind of like the mineral sunscreens. What are some other benefits?

19:00Prof. Rachel Neale:So, it's very stable. So the sun, like, you know how you have to reapply sunscreen every couple hours. But this means that it's a little bit more stable. It's probably going to protect you for a little longer. So kind of guarantee your safety a bit more. And then it also, if you've heard about like European and Asian sunscreens being like really nice and easy to sort of like rub into your skin. Just like applies really nicely and finely. This kind of, why are you laughing?

19:32Dr. Adewole Adamson:It just feels like this classic, like the grass is greener.

19:36Prof. Rachel Neale:Over there, they have the best sunscreens in the world. It's true, though. Have you tried Korean sunscreen?

19:42Dr. Adewole Adamson:I guess I've traveled. I just shove it on my face. I don't think too deeply.

19:47Prof. Rachel Neale:Yeah. I mean, maybe you've had the good one all along, though. It's true. It's true. It's been 20 years and we've been without it.

19:54Dr. Adewole Adamson:Okay. It's true. So it rubs it nicer.

19:57Prof. Rachel Neale:Yeah.

19:57Dr. Adewole Adamson:And then when you have studies look to see if it gets into your blood? Yeah.

20:03Prof. Rachel Neale:There's been studies and it does not get into the blood in the same way. It sits on top more like the mineral sunscreens.

20:10Dr. Adewole Adamson:Oh, awesome. So will you be buying that one now?

20:13Prof. Rachel Neale:Yeah, for sure. I'm going to keep an eye out for it. Okay.

20:17Dr. Adewole Adamson:So here's where we're at so far. Your sunscreen is not toxic, although it does have chemicals in it that depending on the kind of sunscreen you get may turn up in your blood and in super high doses that can cause trouble particularly in rats or in rat studies but most of us all of us are probably not getting those high scary doses so so far I'm sticking with my sunscreen regime Michelle okay sounds good but what's coming up

20:56Prof. Rachel Neale:after the break after the break we're going to be looking at vitamin D oh yes because that would

21:05Dr. Adewole Adamson:could change things for me and I have always wondered am I blocking out too much of the sun's raise? Am I lowering my vitamin D levels too much?

21:16Prof. Rachel Neale:Yeah, with your sunscreen, right? Yeah.

21:18Dr. Adewole Adamson:Yeah. And while we're heading into the break, if you have a friend who's afraid of sunscreen, maybe send them this episode.

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23:38Dr. Adewole Adamson:Welcome back. Today on the show, we're talking all about sunscreen. Should you stop wearing it? Next up, vitamin D. We know it's important. Is sunscreen the reason that your vitamin D levels are too low? Michelle Dang, producer at Science Versus, tell us the science.

23:57Prof. Rachel Neale:Yeah. So let's start with why vitamin D is so important. It's like this middle manager that It helps calcium get absorbed into our gut. And we need calcium to keep our bones strong, right? So a really bad vitamin D deficiency actually can make your bones start to become soft and even break more often. And this can manifest as a disease called rickets in kids or osteomalacia in adults. So I talked about this with Professor Rachel Neal from QIMR Berghofer Medical Research Institute in Australia. And she was like, yeah, you really don't want to go through this.

24:36Dr. Brandon Adler:So certainly being really badly vitamin D deficient, that's worrying and that needs to be corrected rapidly.

24:43Dr. Adewole Adamson:Yeah, I mean, vitamin D deficiency has also been linked to a bunch of chronic diseases, right?

24:48Prof. Rachel Neale:Yeah, we think it might play a role in the immune system. And there's a bunch of studies linking it with things like having worse COVID, worse cancer outcomes, multiple sclerosis.

24:59Dr. Adewole Adamson:Yeah, so super important. So is wearing sunscreen a risk factor here? Yeah.

25:04Prof. Rachel Neale:So, you know, we get some vitamin D from our food, but most of it we get from the sun.

25:10Dr. Adewole Adamson:And so how exactly does that happen? Does the sun stimulate vitamin D in us?

25:17Prof. Rachel Neale:Yeah. So it's super cool. And it's one of the only vitamins that our body can actually make. And it happens from the sun, which is just crazy. So what happens is that the rays from the sun hit our skin cells. And inside our skin cells, there's this chemical that's a cholesterol. And when the UV rays hit that chemical, it changes shape a couple of times from the energy. And then that molecule goes on to become vitamin D. It leaves the skin, goes into our blood. And then here's Rachel to tell you about the rest.

25:55Dr. Brandon Adler:It gets carried in our bloodstream to the liver and then that molecule gets carried to the kidneys and to other cells to become the active form of vitamin D so it can do what it needs to do.

26:06Dr. Adewole Adamson:Okay, so how much sunlight do we need to get enough vitamin D in our lives?

26:14Prof. Rachel Neale:Yeah, so it can depend on several different things like where you live, the time of the day, the time of the season. But just for example, it can be really fast. Rachel told me if you went out in the middle of a summer day in Brisbane on the east coast of Australia. It takes about five minutes wearing shorts and a t-shirt. Wow, that's really quick. It's not long, yeah? Now that's if you have pale skin like Rachel. And another important part here is if you have darker skin, it's going to take longer. About 20 minutes under the same conditions.

26:50Dr. Adewole Adamson:To get enough vitamin D for your daily needs.

26:53Prof. Rachel Neale:And that's in Australia. There are probably across different places in the world. If you're looking at summer and you're looking at midday, you see a similar thing. Okay. Winter, it's going to take longer. 6 a.m., it's going to take longer.

27:07Dr. Adewole Adamson:But it's not huge amounts of time. So does sunscreen affect this? Or do you kind of just get enough sun even if you put sunscreen on to get your vitamin D needs?

27:22Prof. Rachel Neale:It's a valid question because the same exact UV ray that we need to create vitamin D, it's called UVB rays, is the same exact one that sunscreen is designed to block. So let me tell you about a study that we have, which was done by Rachel and her team, where they wanted to test this all out. Does sunscreen affect your vitamin D levels? And so they did this study in Australia and they gathered 600 people for it who said that they don't wear sunscreen that often, about two or less times a week. And then they split them into two different groups. One of them, they told like, just carry on as usual, do what you're doing.

28:07Prof. Rachel Neale:The other group was told to put on sunscreen in the morning every time it was forecasted that the sun was going to be strong enough to harm their skin.

28:18Dr. Adewole Adamson:Okay.

28:19Prof. Rachel Neale:And for the sunscreen nerds out there, that's when the UV index is at UV3 or higher. Yes, you got it.

28:27Dr. Adewole Adamson:Okay.

28:28Prof. Rachel Neale:And that's pretty much every day in Australia except for the winter. Uh-huh. So on these days, the sunscreen group were told to wear SPF 50 sunscreen. And they had to wear it everywhere that they had skin exposed. And to make sure that they actually used it when they were supposed to, Rachel and her team bugged them a lot about it. We sent them text message reminders every week saying the UV index is going to get to three this week.

28:54Dr. Brandon Adler:Make sure you use your sunscreen. And we phoned them and we made sure that they were doing it as much as they possibly could. And how long did this go on for?

29:03Dr. Adewole Adamson:A whole year

29:04Prof. Rachel Neale:A year! Yeah, it was a whole year What an amazing study Okay, so what did they find? So, they measured the vitamin D levels at the beginning of the study after the summer and after the winter and what they found was that throughout the summer it looked like on average vitamin D levels were fine Levels were going up in both groups Mm-hmm. And they didn't see vitamin D deficiencies across the board in the sunscreen group. Oh, so in summer, the groups had the same amount of vitamin D. It wasn't just that the sunscreen group wasn't deficient.

29:43Dr. Adewole Adamson:They actually were all making an equal number on average of vitamin D.

29:48Prof. Rachel Neale:Well, actually, to clarify, the people wearing sunscreen nearly every day actually made a little bit less vitamin D. than the control group. Got it. And so, you know, like people wearing sunscreen were still making, they were still making vitamin D because we know that sunscreen is not like a perfect blocker. It still lets in some of those UV rays.

30:11Dr. Adewole Adamson:What happened in winter then?

30:13Prof. Rachel Neale:Yeah, so they kept following these people. And by the end of winter, they did notice something very interesting.

30:20Dr. Brandon Adler:And there was about a 35 % increased risk of being vitamin D deficient at the end of winter. in the sunscreen group than in the control group.

30:29Dr. Adewole Adamson:Ooh, I mean, they were really wearing a lot of sunscreen there. But what does Rachel make of this? I was really surprised by the results.

30:42Dr. Brandon Adler:Mmm,

30:45Prof. Rachel Neale:okay. Now, everyone in the study made less vitamin D in the winter, which is what you'd expect. Yeah. But the fact that the sunscreen group made less vitamin D throughout the summer is what made the difference here. Because another interesting thing is that our bodies can actually hold on to vitamin D in our fat tissues and release it slowly over several months. I asked Rachel, was it that the daily sunscreen wearers built up less of a storage, like a store of vitamin D that would last them through the winter? Through the winter, correct, yeah.

31:22Dr. Brandon Adler:So the store ended up lower at the end of summer, which meant that as they went down in winter, they ended up lower at the end of winter. And if you imagine that that happened year after year after year, so you've used sunscreen for a year, you're lower in winter, you go up less in summer because you're using sunscreen every day, so now your store's even lower than it was. You end up even lower at the end of the following winter. So with these repeated yearly cycles, you can imagine that if you did this all the time, you could end up quite deficient.

31:52Dr. Adewole Adamson:So I guess now we play the game of risks and benefits, Michelle. Do-do-do-do-do-do. So, okay, wearing a lot of sunscreen does put you at a risk of vitamin D deficiency. But we're not doing this for fun. We're doing this to protect our skin from cancer, effects of aging. So... Is that still real? Because some people online say even that's a lie.

32:26Prof. Rachel Neale:So yeah, here's the concern with skin cancer. Those UV rays from the sun are coming down, hitting our skin, getting through those cells to the DNA and causing a mutation in that DNA. And then again, we're talking about doses. Repeated exposure to the sun can help those mutations accumulate over time.

32:47Dr. Adewole Adamson:Yes, yes. This is what we've known for a long time. So why is, and then the obvious next step would be if you can wear sunscreen, block those UV rays, reduce the chance of DNA damage, you can protect your skin. That's the line from the health authorities, Michelle. But what, is it true when we look at the new science?

33:12Prof. Rachel Neale:So when we get into the real world studies, it gets a little bit messy. Uh-huh. The kind where they gather a bunch of people, ask them about their lifestyle and what they do, whether they wear sunscreen, and then later look to see, you know, do they have skin cancer?

33:28Dr. Adewole Adamson:Yeah.

33:29Prof. Rachel Neale:And some of these studies find that some people who wear more sunscreen get less skin cancer.

33:35Dr. Adewole Adamson:Yeah, what you'd expect.

33:36Prof. Rachel Neale:But, you know, not every study finds that. People really like to point to this one study that was done in 2023 out of the UK. Okay. where it looked at the health data of over 400 ,000 people, and it found that people who wear more sunscreen more often are more likely to get skin cancer.

33:57Dr. Adewole Adamson:Wait, so that people who wore more sunscreen were more likely to get skin cancer? Mm-hmm, yes. That sounds, big study, 400 ,000 people, It sounds damning for the sunscreen propagandists out there like me. But it is making me wonder, could it be that the people who were wearing more sunscreen were actually out in the sun more often? And they were badly applying sunscreen. And that's why they had more skin cancer.

34:36Prof. Rachel Neale:Yeah, you are right on track. The authors of this study came out to say that people online are misinterpreting this study. And even though they found a link, what's likely really happening here is that people who wear more sunscreen are more likely to go outside and be outside in the sun. But maybe under this false security because maybe they're not wearing enough of it or not reapplying and that kind of thing. So do we have any better studies here that can help us? Yeah, so Wendy, we actually have one RCT, randomized controlled trial. Uh-huh. And this one happened in Australia. It looked at 1 ,600 people.

35:16Prof. Rachel Neale:And similar to Rachel's study, it split these people into two different groups. One was given sunscreen and told to wear it every day. And the other was told to carry on as usual, do whatever they want. Okay. And Wendy, they followed these people for over a decade. Wow. Wow.

35:35Dr. Adewole Adamson:This is an amazing study. This is exactly what we need. 1 ,600 people followed for a decade because skin cancers can take a while to develop. So what did they find? Did the sunscreen group get less cancer?

35:50Prof. Rachel Neale:Yeah. So they looked to see who in the study got skin cancer. And there are three main types of skin cancer. There's squamous cell carcinoma, basal cell carcinoma, and then there's the scary one, melanoma. which is more likely to spread and kill you. And what the RCT found was that the sunscreen worked pretty well for that one type of skin cancer, squamous cell carcinoma. It basically dropped cases 40 % between the two groups.

36:20Dr. Adewole Adamson:Aha, but what about melanoma?

36:23Prof. Rachel Neale:Yeah, so when it came to melanoma, the evidence was actually less clear. Interesting. There was 11 people who got melanoma in the sunscreen group versus 22 in the control group. That's a 50 % lower risk, Michelle. Yeah, but it actually didn't come out to statistically significant, probably because the cases were just too low.

36:46Dr. Adewole Adamson:Okay. Interesting. It does seem like then sunscreen is still protecting you from skin cancer. That story is still true, even if it's not your silver bullet, right?

36:57Prof. Rachel Neale:And yeah, like the dermatologists I spoke to, they were like, hey, if we were to redo this study, looking at melanoma, which is the scarier one, maybe the data would be even stronger today because back then they were using SPF 16 and now we're using SPF 30, SPF 50.

37:15Dr. Adewole Adamson:And in that study, did it matter about your skin tone? If you have darker skin or lighter skin, does that affect your risk here?

37:21Prof. Rachel Neale:Yeah, so here's the thing with that study. Most of the people in it were white, which brings us to this other idea where some people say that people with darker skin don't get the same benefits from sunscreen.

37:36Dr. Adewole Adamson:Okay. Well, we already know if you've got darker skin, you're at an increased risk of vitamin D deficiency. So if we're playing this risk-benefit game, got to be some strong benefits here. Is it true that if you have darker skin, you're at a lower risk of skin cancer?

37:51Prof. Rachel Neale:So I talked about this with Dr. Ade Adanson, who's a dermatologist from Dell Medical School at University of Texas, Austin. And based on a day's own experiences in the clinic, like with melanoma, he told me.

38:04Dr. Brandon Adler:Well, one, as a dermatologist, if I just think about the people that I see, right? And like, I can only may think of one or two Black people that in, you know, doing this for 15 years, having actually seen or diagnosed one, right? You don't see it.

38:23Dr. Adewole Adamson:A melanoma. He's talking about melanoma specifically? Yes, exactly.

38:27Prof. Rachel Neale:If you look at the data, people of color do get melanoma a lot less than white people. For example, a black person's risk of getting melanoma is 30 to 40 times less than a white person. And that's specifically the kind that spreads. And not only that, when it does show up in people with darker skin, it's often showing up in a very particular way.

38:51Dr. Brandon Adler:You know, people of color, they mostly get melanoma on the palms of their hands, soles of the feet, places that are not related to sun exposure.

39:01Prof. Rachel Neale:So all of this was very, like, curious to Ade. And he wanted to take a step back and understand whether sun exposure is linked to melanoma and people of color in the first place. Like, is there a connection here at all? And so he said,

39:17Dr. Brandon Adler:You know what? Let me do a systematic review, which is at the top of the evidence pyramid. Right. You know, you get all the studies looking at this and see what what comes out of it. Is there actually data to support UV is an important risk factor for melanoma?

39:33Prof. Rachel Neale:So they got together this big review on it and he and his team wrangled up the data, crunched the numbers. Yeah. And the answer to whether or not sun exposure is linked to melanoma and people of color.

39:45Dr. Brandon Adler:And to sum it up, no, it is not. It is not in anyone that identifies as non-white. Not Asian, not Hispanic, not black, right? There is like almost zero data to support that.

40:05Dr. Adewole Adamson:Whoa. And why is that? Melanin is super protective for melanoma? What's going on?

40:14Prof. Rachel Neale:Yeah, so that's also really cool what's happening there. no matter your skin color, we all have these cells in our skin called melanocytes that make the pigment melanin. And when we step outside, our melanocytes start pumping out melanin in response to the sun. And that's why you tan. Yeah. Over time, you would eventually tan. But before that, like Ade told me that melanin actually gets packaged up and is like sent, Like it makes its way toward the surface of your skin.

40:48Dr. Brandon Adler:I don't know if you've ever noticed a phenomena in the first, you know, 10, 15 minutes of some people getting some sun. They make it slightly, you know, darker. That's your melanin. If you have enough, at least, that's it moving out around the cell in order to protect the DNA from the incoming UV exposure. That's like one immediate response.

41:09Dr. Adewole Adamson:Wait, so the melanin sites, the cells that make the melanin, then the melanin is like sunscreen for your DNA, like natural sunscreen for your DNA?

41:24Prof. Rachel Neale:Yeah, so like this melanin, it's directly responding to the sun, it's moving up there, and it's wanting to protect you from those UV rays and in essence protects you from the DNA damage that could cause skin cancer. Wow, that's so cool. And the more melanin that you have in your skin, the more likely it's doing a similar job to sunscreen. Here's a day again.

41:52Dr. Brandon Adler:So it is helping, you know, absorb some of the harmful effects that the UV will have on the DNA. And, you know, depending on how dark you are, you know, you can have, you know, SPF of 15 plus equivalent, at least, if you're of a darker skin tone.

42:14Dr. Adewole Adamson:That's so cool. It is, right? Yeah. So does this mean if you have a darker skin tone, then wearing sunscreen is not a good idea because then you're at an increased risk of vitamin D deficiency and you don't get this skin cancer benefit? But I guess specifically for melanoma, there are other skin cancers to worry about.

42:35Prof. Rachel Neale:Yeah, so you're right on track. After studies like A Days came out, countries like Australia actually changed their guidance on sunscreen recommendation. So people that are of the darkest skin types don't routinely need to wear sunscreen to prevent skin cancer. They classify it by what's called the Fitzpatrick scale. So there's six different skin tone types. And the two darkest skin tones are not recommended to wear sunscreen for skin cancer in Australia. So we'll throw that up on screen.

43:09Dr. Adewole Adamson:Uh-huh.

43:10Prof. Rachel Neale:On the flip side, though, places like the U.S., the American Academy of Dermatology, haven't changed their guidelines. And this is something that annoys a day a lot.

43:19Dr. Brandon Adler:We're not science-based. The recommendation is not. And it's also wild because we're in this era of personalized medicine, right? There should be personalized risk stratification related to the sun. Anyone saying sunscreen saves lives for personal color is lying. That is a bald-faced, bald-faced lie.

43:45Dr. Adewole Adamson:Should people of color wear sunscreen then? Does this change the equation?

43:48Prof. Rachel Neale:Yeah, so I asked today and he said that, you know, sunscreen isn't useless. Like it still prevents sunburn and could have cosmetic benefits because we think that melanin better protects against UVB rays versus UVA. And UVA rays are the ones that penetrate a little bit deeper into our skin and messes with things like elastin and collagen and can contribute to like an effect of aging.

44:17Dr. Adewole Adamson:Mm-hmm. Okay. And wrinkles and things like that. Uh-huh.

44:21Prof. Rachel Neale:I asked Ade, like, does he still recommend his patients who are people of color to wear sunscreen? Sure.

44:28Dr. Brandon Adler:I do. Sunscreen has a lot of important uses. No matter your skin type, you can sunburn, right? That is possible. People like to use it for anti-aging. But, you know, for listeners that might not see my image. I'm a black male dermatologist. And so, yeah, I wear sunscreen. I went to the beach like a few weeks ago. I had sunscreen on, you know, I didn't want to get burned. But do I wear it daily? No, I don't. But that's me. That's my, I'm a different risk say than somebody that, you know, looks like Pippi Longstocking.

45:09And I guess if for anyone worried about a vitamin D deficiency, no matter your skin tone,

45:18Dr. Adewole Adamson:can you just take a supplement if you still want to wear sunscreen? Is vitamin D supplementation okay?

45:26Prof. Rachel Neale:Yeah, going back to Rachel Neal, who we heard about with the vitamin D study, I asked her, like, can you just take a supplement? And she's like, yes, that's the easy fix to this if you're worried about it.

45:39Dr. Adewole Adamson:Great. Okay.

45:40Prof. Rachel Neale:Now, Rachel herself, she doesn't look like the B-long Socking, but she does have pretty pale skin. And skin cancer is something she's very concerned about. She's also had it before.

45:50Dr. Brandon Adler:When I brush my teeth, I put my sunscreen on every day. So for me, I think that's really important. We know that that reduces risk of skin cancer, and I've had three. So I had my first skin cancer when I was 29, which shows how problematic the Australian sun can be. And it's the same in other parts of the world as well where there's a really high UV, which means that just popping outdoors is enough to cause damage. All right.

46:17Dr. Adewole Adamson:Is it time for our sunscreen summary? Sounds good. Okay. So sunscreen does have chemicals in it, obviously. Some of them can get into our blood. But as far as we can tell, they're not causing harm while they're there, at the doses that they're there. If you are worried about it, though, you can try mineral sunscreen, which is more likely to stay on the top of your skin and not go into your blood. Sunscreen does increase your risk of having vitamin D deficiency, which is particularly concerning if you have darker skin. You're at a higher risk of that. But on the other hand, if you have darker skin, you also don't need to worry so much about melanoma.

47:03Dr. Adewole Adamson:And not great evidence that sunscreen can protect you from that. But if you have lighter skin, then sunscreen is going to protect you from skin cancer. Yeah, you got it. I think based on all of this, I'm going to keep wearing my sunscreen. But I'm going to start taking a vitamin D supplement. Okay. Yeah, that's good. All right. We got a lightning round ready to go? Yes. Lightning round, lightning round. It's where we say some quick facts that can help you in your day. We've had a lot of questions about this, just the practicalities of sunscreen. If you're still on Team Sunscreen after listening to this episode, here's some tips and tricks about putting it on properly.

47:48Dr. Adewole Adamson:Okay. When should you wear it?

47:51Prof. Rachel Neale:Okay. So if you open up your weather app, you will see a section that says UV index. basically telling you how strong the UV rays are that are coming through the atmosphere. Okay. Weather app.

48:04Dr. Adewole Adamson:Here we go. Yeah. All right. So here's what I got. Melbourne, middle of winter, low all day.

48:12Prof. Rachel Neale:It's going to be one. So you actually, so like you need to wear sunscreen if the UV hits three or above. So today you actually don't need to wear sunscreen.

48:22Dr. Adewole Adamson:Next question. Which SPF should you wear?

48:25Prof. Rachel Neale:So in Australia, they recommend SPF 50 plus. Other places recommend 30 plus. However, the dermatologist I spoke to said you might as well wear 50 because we know from studies that most of us are bad at putting on sunscreen and that we don't put enough of it on.

48:41Dr. Adewole Adamson:Okay, speaking of badly putting on sunscreen, even though I'm mad for it, I shove it on as soon as I leave the house. But I hear you need to put it on 20 minutes before.

48:54Prof. Rachel Neale:Is that real? You do. Yeah, it's fascinating because you actually need time for it to dry and set on your skin. It will adhere a little bit better and then you're kind of like guaranteeing protection. Oh. Mm-hmm.

49:10Dr. Adewole Adamson:All right.

49:11Prof. Rachel Neale:Do I need to wear it if I'm behind a window? It's surprising. Like, the windows block some of the rays, but let's do a bit of UVA rays.

49:23Dr. Adewole Adamson:Do you know there's a fascinating case report of a guy who was a truck driver and for decades would drive, half of his face would be exposed to sun and the other half would be in the shade. and you can, it was published in a scientific journal because you could actually see more wrinkles on the side of his face. Yeah, exactly. That got the sun.

49:48Prof. Rachel Neale:Yeah, yeah. So those UVA rays are getting through and we know that they're connected with signs of aging and also play like a little bit of a role in skin cancer.

49:56Dr. Adewole Adamson:Okay, last question. How much do you actually need to put on?

49:59Prof. Rachel Neale:So for the whole body, an easy guideline is one full shot glass of sunscreen. What about just the face? Yeah, so let me get out my measuring tool. I'm showing you a teaspoon, a five milliliter teaspoon, which is the same in US and Australia. And the recommendation is one whole teaspoon for your face, ears, and neck. But for your whole body, you actually want seven of these. Thanks, Michelle. Thanks, Wendy.

50:28Dr. Adewole Adamson:That's science versus. How many citations are in this week's episode? There are 92 citations. and if people want to see them in all their glory, learn more about the science of sunscreen, where should they go? Head over to our transcript that you can find in the show notes. This episode was produced by Michelle Dang with help from Meryl Horne, Rose Rimler and Aketi Foster-Keys. We're edited by Blythe Terrell, Wendy Zuckerman, that's me. I'm the executive producer. Fact-checking by Erica Akiko Howard. Mix and sound design by Bobby Lord. Music written by Bobby Lord, Bumi Hidaka, So Wiley, Emma Munger and Peter Leonard.

51:01Dr. Adewole Adamson:Science Versus is a Spotify Studios Original. You can find us on Spotify. We are also on YouTube. You can like and subscribe. If you liked this episode, please share it with your friends. Helps other people know about the science in the world. I'm Wendy Zuckerman and I'll back to you next time.

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