20:11
As the season turns from winter gloom to the sunshine of spring and summer, we're all excited to get back outside and enjoy the outdoors again. But as you're packing up the beach bag, there's one item that you might have heard a lot of mixed messages about, especially in online wellness spaces: Sunscreen. So let's reapply some knowledge to help you sun-block any sunscreen myths this summer. [♪INTRO] Let's start with the basics. Despite what anyone else tells you, you absolutely need sunscreen. Besides bringing us light and warmth for a gorgeous day at the beach, the sun also brings ultraviolet, or UV, rays that can cause sunburns and skin cancer.
UV rays are mainly categorized as UVA or UVB. Both of them can cause cancer, but UVB is the one that leads to those classic sunburns, whereas UVA contributes to premature skin aging. Sunscreen blocks most of those harmful UV rays from reaching your skin. Which is super important because some researchers think getting just one blistering sunburn could be enough to increase your lifetime risk of melanoma by 50%! Even if you're someone that only tans and never burns, that sun-kissed glow is still a sign that you're getting some skin damage.
Whenever your skin cells sense UV radiation, they produce more melanin to protect your DNA from further bombardment. Melanin absorbs some of the radiation before it hits your DNA, and it also makes your skin look darker, hence the tan. That's the same reason why people living closer to the equator tend to have darker skin tones, because the UV exposure is higher there and their skin needs more protective melanin. But here's the thing. All people regardless of age, race, sex, and whatever else should be wearing sunscreen every time they go out in the sun. And that's not just me saying that.
Both the American Academy of Dermatology and the Mayo Clinic state that all people need to use sunscreen. Even though it's true that having naturally higher melanin means that dark skin doesn't burn as easily, everyone/ can get sunburned, and everyone can get skin cancer. That's because melanin can't protect you from 100% of UV rays, meaning that no matter how dark someone's skintone, they're still going to get at least some UV exposure damaging their DNA. This myth has led to a lot of people of color thinking that they can't get skin cancer, which leads to later diagnoses and disproportionately poor outcomes.
It's also worth mentioning that the warning signs of skin cancer can look different on darker skin. If you have a dark skin tone, it's important to know what a questionable spot looks like on your skin type. So case closed! The American Academy of Dermatology recommends that everyone should wear sunscreen. But do we need it all the time? Like, if it's overcast, it can be tempting to think that you don't need sunscreen. If I can't see the sun, it can't see me, right? But no, if the sun is up, then UV rays are present, cloudy or not. The official recommendation is that everyone should wear at least SPF 30 on any exposed skin anytime they're outside.
Even indoors, if you sit near a window, some UV rays can still come through. And the need for sun protection doesn't stop when summer break ends. Just because there's snow on the ground, doesn't mean you can skip your sunscreen. Bright white snow reflects UV rays and bounces them all around, meaning your skin gets UV from multiple directions instead of just from above. This reflective property is called albedo, and it happens around sand and water too. But usually when you're on a beach vacay, sunscreen is already on your mind.
It's harder to remember when you're bundled up and can't feel the tip of your nose, but it's just as important! In any case, dermatologists say you need at least SPF 30 during the day. Outdoors and indoors, summer and winter, sunny and cloudy! Speaking of SPF, let's talk about what those letters actually mean. When you're browsing the sunscreen aisle at the drugstore, you'll notice that the big number on the front of the bottle is its SPF. SPF stands for sun protection factor, and that number is a ratio for how well the sunscreen protects you from the sun's rays.
A quick and dirty way to think of SPF is that the number on the bottle equals how many times longer you can stay out in the sun without burning. So if you would have burned in 5 minutes without any SPF at all, slathering on SPF 30 means you could kick it poolside for two and a half hours, no worries. But that's just a rule of thumb, and the strength of radiation changes a lot during the day. The more technical explanation is that SPF 30 means only one-thirtieth of the sun's UV rays make it past the sunscreen to your skin cells. So, one divided by thirty is about 3% of the rays hitting your skin. In general, higher SPF numbers do
offer more protection than lower SPF, but it's not a linear relationship- SPF 30 isn't doubly as effective as SPF 15 in the way you might think. Like, SPF 30 blocks 96.7% of UV rays, while SPF 60 blocks 98.3%. So doubling the SPF number only increases the effectiveness by 1.6%. The number of rays hitting your skin is cut in half, but there's only a marginal increase in protection for a much bigger number. Because of this, experts have proposed caps on how high you can market your SPF.
This is to avoid misleading customers about the degree of sun protection a product can provide. Previously, the proposed cap had been SPF 50, so the highest number brands could write was SPF 50+. But in 2021, the US Food and Drug Administration decided that the effective difference between SPF 50 and 60 was meaningful enough to update that proposed cap to SPF 60+. But most specifically, SPF measures how much UVB is able to reach your skin. Remember, that's the burn-y kind of radiation. That's important because even if you're using an SPF sunblock, it won't always have what it takes to block skin-aging UVA rays too. To ensure your sunscreen also includes UVA protection,
look for "broad spectrum" or PA+ bottles. As if all that wasn't complicated enough, I have another wrench to throw in this calculation. The advertised SPF is the number manufacturers get for perfectly applied sunscreen swatches. In the lab, that's a precise 2 milligrams per square centimeter of coverage. Or in normal people numbers, that's about a quarter of a teaspoon for your face, and about 1 ounce, like two thirds of a shot glass, for your whole body. Of course, people come in lots of different sizes, so you might need more or less depending on how much skin you need to cover.
But the shot glass method is a good reference point. In reality, most of us are only using about a quarter of the recommended sunscreen, so we're getting way less SPF than what's listed on the bottle. Plus, you're supposed to reapply every 2 hours. So if you're a little patchy with your initial application, or you're sweaty or wet, or if you miss your 2 hour refresh, you're also not getting your full SPF power. And if your sunscreen has expired, it's even less effective. So check your sunscreen bottles, bulk up on application, and don't F around with your SPF! And to keep you company while you reapply, we've got a quick ad to show you.
Thanks to Privacy.com for supporting this SciShow video! Privacy.com exists to prevent your information from being leaked in data breaches, prevent fraud, and control your online spending. They do that by creating a secure layer of temporary card numbers between your real card and the merchant. So even if a merchant gets compromised, there's nothing to steal. Your actual bank account or credit card information is shielded from merchants and, therefore, from potential merchant data breaches.
One of our producers actually could really use privacy.com. Whenever one of our long Deep Dive episodes goes live, we all get together for a virtual watch party. And during the most recent watch party, someone bought $1700 worth of gear using her money. It wasn't her! She was trying to enjoy the goodest dogs ever, saving children in Alaska, with their tongues flopping adorably out of their mouths. But that was all tainted by this emergency. And that's the kind of headache that Privacy can address. Our producer, and you can sign up for a free plan with no transaction fees for domestic purchases in exchange for more peace of mind. And Privacy doesn't sell customer data, ever and can protect you in a world where data breaches happen every day.
So next time you're watching the real Balto story, you can cheer, cry, and learn about the life saving power of vaccines without being interrupted by fraud. Go to privacy dot com slash scishow- that's P-R-I-V-A-C-Y dot com slash scishow- or the link in the description, to get your 5 dollar sign-up bonus today. That $5 can be used on your first purchase. We've talked about why too much UV exposure is bad. And it is. But, there is one thing that a little UV is good for: Making vitamin D. When sunlight hits your skin, the UV rays zap a certain type of lipid molecule in our bodies
that then breaks down into the biological precursor for vitamin D. Then, your body takes that precursor and finishes it up to make vitamin D. So if we block most UV from reaching our skin, then won't we block most of that good vitamin-making power, too? It's true that sunscreen can lower vitamin D production. BUT scientists think that in reality, we aren't using enough sunscreen for that to be a significant issue. There's definitely room for further research, but with the way most people are actually using sunscreen, scientists haven't found any evidence that SPF is significantly hindering our vitamin D production.
Overall, the benefits of wearing sunscreen vastly outweigh the cost of slightly lower vitamin D levels. Because you don't actually need that much UV to max out your vitamin D factories. Remember that sunscreen can never block 100% of UV rays from reaching your skin. So chances are, if you're getting enough sun to warrant wearing sunscreen, you're probably also getting enough UV to produce normal amounts of vitamin D. If you're tanning at all, then you're definitely getting enough. And the American Academy of Dermatology does not recommend any kind of min-maxxing to try to get the most vitamin D with the least risk of skin cancer.
Just, like, don't do that. Besides, you should also be getting vitamin D from your diet! Fatty fishes, fortified dairy and cereal products, and some mushrooms can help meet your vitamin D needs. If you're really concerned, you can also take supplements. Some people might feel resistant to the idea of taking supplements, given that your skin has built-in vitamin D factories as is. But that myth plays into something called the naturalistic fallacy, which states that natural things, like making your own vitamin D, are always better than taking manufactured supplements or slathering sunscreen chemicals on your skin. But doing it the "natural" way means significantly
increasing your risk of skin cancer by not using SPF. This is a case where we should be willing to accept a little help from science. So, while there is some evidence that sunscreen can reduce vitamin D production, the official recommendation isn't to just stop using sunscreen. You should definitely still use sunscreen. But if you're worried about your vitamin D, dermatologists recommend adding a supplement to your routine. Part of the naturalistic fallacy is an aversion to anything that's called "synthetic" or a "chemical." One chemical that has received considerably bad press is called oxybenzone.
Sunscreens are generally sorted into two broad categories- chemical or mineral. Mineral sunscreens rely on ingredients like zinc oxide or titanium dioxide that sit on top of your skin and reflect the sun's rays like a UV mirror. Chemical sunscreens, on the other hand, work by absorbing all the UV rays themselves so your skin cells don't have to. Like a UV shock absorber! Oxybenzone is one of the ingredients that can do this absorption in chemical sunscreens. And because oxybenzone needs to sink into your skin in order to work, it's become a hotbed for naturalistic controversy. In particular, people are worried
about oxybenzone disrupting hormones. This myth seems to be based on a study conducted back in 2001, where researchers fed large amounts of oxybenzone to rats. But humans are not rats, and you're probably not eating your sunscreen! To put this in perspective, you'd have to eat like 100 grams of oxybenzone a day for four days in order to get the same relative amount as these rats. If you're using sunscreen on top of your skin, because you should be, it would take you 277 years to get the same amount of oxybenzone in your system as these rats. There are some real concerns about oxybenzone. It is banned in some countries because it can harm coral reefs. And sometimes it can cause allergic reactions.
But that's all different than causing disease! It's okay to avoid stuff for valid reasons, but we shouldn't be spreading total misinformation, either. Another unfortunate myth that has sprung from the naturalistic fallacy is that you can make your own sunscreen. You cannot make your own sunscreen! I'm looking right at you, raspberry and carrot seed oils! Even though these have some natural SPF properties, they're only rocking a whopping SPF 2.
A study from 2020 made 15 different DIY sunscreen recipes from across the internet, then analyzed their SPF. 3 of the 15 recipes didn't contain any SPF at all. And the other twelve clocked in at less than SPF 6. Remember, the recommended coverage is at least SPF 30! Most of the DIY recipes are concocted from oils, beeswax, and zinc oxide. Although zinc oxide is a sun-blocking ingredient in many mineral sunscreens, its quality and concentration is crucial for the safety of the final product. And the zinc oxide formulation also affects its sunblocking abilities. Like in the pigment form, it hardly does a thing, and the nanoparticle forms can vary drastically in size and quality.
But the microstructure of zinc oxide isn't something that most average folks who are trying to make their own sunscreen would be able to tell apart. Even worse, regulatory agencies warn against inhaling zinc oxide in any amounts, so working with those fine powders in your home kitchen could be hazardous. Unless your kitchen is equipped with tools for factory-precise measurement, lab quality environmental control, and perfectly homogenous mixing, then every single swipe of your homemade sunscreen could give you wildly different amounts of protection.
The impressively wide range of SPF 0 to 6! Homemade sunscreen is basically equivalent to just rubbing oil on your skin. Good for moisture, but bad for UV protection. For proper protection, professionally manufactured sunscreen should be your go to. Whether you're soaking up some rays on the beach, skiing on an overcast day, or just taking a walk around the neighborhood, it provides the UV protection that dermatologists say we all need. Hopefully, this good healthy slather of knowledge will help protect you from skin cancer and misinformation. [♪OUTRO]
