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Sun Protection with Dr Jonette Keri

06/09/21 Jonette E. Keri, MD, PhD, University of Miami, Miller School of Medicine|Miami VA Hospital;

Season 3 | Episode 3


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>> Dr. Jonette Keri: If you think of it like a bank account that builds up, every ray of sun that touches your body leads to a cumulative result. So, every ray adds up. So, unlike the bank account, which you want to grow, the sun, you don’t want it to grow. You want to keep that bank account low. You want the lesser amount of sun to touch your skin.

>> Joe McIntyre: Hello! And thanks for tuning in to what I feel is going to be a very important episode of the Merck Manuals Medical Myths Podcast. I’m Joe McIntyre, thanks for being here. On today’s episode, we’re thrilled to welcome back Dr. Jonette Keri. Doctor Keri is an associate professor of dermatology and cutaneous surgery at the University of Miami, Miller School of Medicine. She is also Chief of Dermatology Service at Miami VA Hospital. If you missed our first episode with Dr. Keri, we busted all kinds of myths about acne, including where it comes from, how to prevent it, and how to get rid of it. Dr. Keri, thanks for coming back!

>> Dr. Jonette Keri: Nice to be here Joe! Thank you.

>> Joe McIntyre: Now today we’re going to talk to Dr. Keri about a more serious topic; skin cancer prevention. When it comes to sunscreen or sunblock, I’m sure we’ve all heard plenty of confusing information about how it works, when it works and what the best type to use is. So, Dr. Keri, let's jump right into it. Are tanning beds more dangerous than sun exposure when it comes to skin cancer risks?

>> Dr. Jonette Keri: So, what people need to know about tanning beds is we have to go back a little bit and we have to think about what type of ultraviolet radiation we get from the sun and the bad boys that we worry about in dermatology in general are UV-A and UV-B. Tanning beds are UV-A so they are a specific ultra violet wave length. We do not like tanning beds. Tanning beds aren’t good. Let me just put that right out there. They give a multitude of higher does off UV-A. UV-A doesn’t cause you to burn. UV-B causes you to get the sunburn. So, people think they’re safe and they all into a trap. But what happens, with tanning beds is that UV-A actually penetrates deeper than the UV-B and when it penetrates deeper it can not only cause skin cancer, and this is the point there’s a lot of contention about. We more data about the sun, because the sun’s been around forever, then we have about tanning beds. But there is very good data, probably from about 15 years ago now, it’s been replicated, that even going to a tanning bed very infrequently. There was one study said any exposure increased the risk of melanoma, the most deadly of skin cancers. And let's just forget about the skin cancers for a minute, because a lot of people think they’re not going to ever get cancer. Let’s talk about aging. UV-A is the bad boy with aging. It gets down deep and can lead to more wrinkles.

>> Joe McIntyre: Now is it true that there is such a thing as too much SPF in sunscreen? For example, is 100 SPF sunscreen twice as effective as 50 SPF? How does that actually work?

>> Dr. Jonette Keri: It isn’t like that. When you get to a SPF 30, you have about 97% protection from UV-B. Nothing is 100%, but when you get up to 100 SPF you gain the percentage points into around the 99% area. So, you’re going up a little bit. Why do people think the 100 SPF is better than the 30 SPF. It’s about how much they put on. Most people don’t put enough sunscreen on. So, you might get a little bit added benefit if you put the same amount on of the 100 SPF than you do of the 30SPF. But remember with an SPF 30 you get about 97% blockage of UV-B

>> Joe McIntyre: So, for most people 30 SPF should be plenty of sunblock protection for them?

>> Dr. Jonette Keri: So long as they put on about the size of a shot glass, an ounce for their whole body. And sometimes I do that plus a little bit more for my face. So, I protect the face even more. As long as they get enough on and they reapply. So, the longest a sunscreen will act when you’re out in the water, and this is not waterproof, everyone should know these are not waterproof sunscreens. Water resistance is about 80 minutes. 

>> Joe McIntyre: Now if the sun isn’t out, it stands to reason that the clouds are blocking the powerful UV Rays. Is that actually the case?

>> Dr. Jonette Keri: They block a little bit. But you can still get up to 80% of the UV exposure on a cloudy day.

>> Joe McIntyre: Now how about spray sunscreen versus lotion or ointment style sunscreen. Is one better or worse than the other for you?

>> Dr. Jonette Keri: Well for me it’s the one that’s going to get on the patient and that people are going to use. The sprays have a little problem and sometimes people don’t get enough on. The other thing is they do sometimes have a smell from the aerosol, but in general spray sunscreens can work, you just have to get enough on. I would spray them only outside because they do leave a lingering smell.

>> Joe McIntyre: How about when, or what time of year do we need to wear sunscreen? Is true that you only need to wear sunscreen in the summer months?

>> Dr. Jonette Keri: You should wear sunscreen all year-round. People always worry that if they’re up north, they’re going to be vitamin D deficient. You only need a little bit of sun up north. If you can get your hands out or your face out on some days, for ten minutes you’ll be fine. In Miami, we wear it year-round everywhere because we’re going to get ambient sun just walking to our car. So, I like sunscreen every day of the year, regardless of where you are. For the people who might be concerned about vitamin D deficiency, which is a true phenomenon and occurs, you can get a little bit of exposure in ways you might not even realize. Maybe you're driving. Maybe you’re walking to your car without your mittens on. And also, vitamin D supplementation does help.

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>> Joe McIntyre: Whether you’re a parent or seasoned professional, a medical student or a caregiver, the Merck Manual’s has the right medical information in the best format. And it’s always free, easy to access, and readily available for you.

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>> Joe McIntyre: Now is it true that in the early morning and evening, it’s not always necessary to wear sunscreen because the UV rays at those times of day aren’t as strong as that prime noon hour?

>> Dr. Jonette Keri: Again, in Miami, we wear sunscreen all day long. But in other parts of the country, you could probably get away with less sunscreen use. But I hate to diverge from my comment which is, I like sunscreen all the time. Are you going to be at less risk when you’re out at 7:00 at the setting sun, for sure.  We know that. So, if you’re running out to take your dog for a walk at 7 p.m. you may not want to slap on your sunscreen. I get that. But in general, get into the habit of using sunscreen like you brush your teeth. Use it every day, all days. And for those who aren’t worried about cancer, it prevents premature aging.

>> Joe McIntyre: Now is there any harm in using things like coconut oil, butter, or any non-sunscreen products on your skin when you’re out in the sun?

>> Dr. Jonette Keri: So, think of it as an amplifier. Think of the oil as sort of an amplifier. And that’s why people use them. They want to get tanner. They want to get tanner quicker. We don’t like people putting that on and then going and relaxing around the pool in the sun. But those products are good for other reasons, so I don’t want people not to wear them.

>> Joe McIntyre: Now I assume this is in a similar vein. Are tanning lotions protective or do they offer the same sort of benefits as coconut oil or other products?

>> Dr. Jonette Keri: I’m not against self-tanners and tanning lotions. They offer, probably about an SPF 4, just so you know that. They give a little bit of sun protection. I would say to use a sunscreen with it. But if people feel more attractive with a tanning lotion, I say go for it. But use it with a sunscreen.

>> Joe McIntyre: Now how about if your skin doesn’t burn? A lot of people may not get red. They might go right to tanning, does it mean that you’re actually safe from the sun’s UV rays?

>> Dr. Jonette Keri: You know, that’s another myth that we have to make sure we educate people about. You have some protection that a very fair skinned person doesn’t but you can still get cancer. There’s some bad data behind that myth and that is that when we find melanomas in people in, let's say Hispanic origin or African American, we often find them at a later stage because they don’t think they can get skin cancer. So, we want them to be aware of changes on their skin. And for those populations who don’t want to wear it because they don’t burn, it all goes back to aging again. Skin looks aged when it doesn’t have the same skin tone, so when you wear sunscreen, you keep the tone more even. So that’s a way to get people to wear it.

>> Joe McIntyre: I want to ask this again. I think you just busted it, but let’s just be clear. African Americans and people with darker black skin and Hispanics and Latinos, they also need sunscreen just as much as those with fair skin tones. Correct?

>> Dr. Jonette Keri: Right, and you also want to watch those populations for other places where you can get a skin cancer, on the palms, on the soles, even places where the sun doesn’t shine.

>> Joe McIntyre: Let’s get to a little bit of truths here. What is the best way to protect yourself from the sun and reduce your risk of skin cancer?

>> Dr. Jonette Keri: How I think of sun protection is I don’t just think of sunscreen. I think of hats. I think of long-sleeved shirts. I think of seeking the shade. I will walk down the shady side of the street when I around the campus at the hospitals because I always want to try and stay in the shade. But remember, sun reflects off of concrete. It reflects on the water at the beach, it reflects off the sand. It reflects off glass windows. So, you really want to have a multi-focused approach. You want to have that hat on. You want to have some long-sleeves or sunscreen. You maybe don’t want to be out at noon, doing cross-fit which a lot of my patients were doing for a while. So, you want to think of all the different ways you can cut down on your sun exposure. And I'll end with this one though Joe. If you think of it like a bank account that builds up, every ray of sun that touches your body leads to a cumulative result. So, every ray adds up. So, unlike the bank account, which you want to grow, the sun, you don’t want it to grow. You want to keep that bank account low. You want the lesser amount of sun to touch your skin.

>> Joe McIntyre: Now Dr. Keri, before we let you go, where should our listeners head to for information about skin cancer prevention, how to properly apply sunblock, things like that. Where should our listeners head to?

>> Dr. Jonette Keri: We want to give them resources. Their doctor, their dermatologist, the Merck Manual, The American Academy of Dermatology. These are all good places to start your research on skin cancer and sun exposure.

>> Joe McIntyre: Dr. Keri, thank you once again for joining us. It was really enlightening conversation and one that includes a ton of helpful information about how to prevent skin cancer, how to wear your sunblock and the best ways. Would you mind, one more time staying with us for a third part discussion for dermatology?

>> Dr. Jonette Keri: Sure. Of course! And remember, medical knowledge is power, pass it on. 

>> Joe McIntyre: I love that. Thank you.

>> Dr. Jonette Keri: You’re welcome.

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