YouTube: https://youtube.com/watch?v=bvG4sy_YfXM
Previous: Number Needed to Harm: Treatments Can Hurt You
Next: Healthcare in Germany

Categories

Statistics

View count:100,420
Likes:3,623
Dislikes:34
Comments:372
Duration:05:57
Uploaded:2014-07-20
Last sync:2019-06-13 14:30
Thanks to Audible.com for supporting this episode of Healthcare Triage. You can download a free audio book of your choice at Audible.com: http://www.audible.com/triage

When I was a kid, I remember people talking about putting on suntan lotion to help them absorb the sun's rays. Those days are over. Too much sun can be terrible for you. Besides the fact that it significantly increases the risk of skin cancer, the sun will age your skin and make you look older, too. Who wants that? Today, we use sunscreen to protect us from the sun. But most of us are doing it wrong. How so? Watch and learn.

Those of you who want to read more and see references can go here: http://theincidentaleconomist.com/wordpress/?p=56836
Additionally, Aaron's new book is out! Please consider buying a copy. He'd really appreciate it! http://dontputthatinthere.com/#buy_the_book

John Green -- Executive Producer
Stan Muller -- Director, Producer
Aaron Carroll -- Writer
Mark Olsen -- Graphics

http://www.twitter.com/aaronecarroll
http://www.twitter.com/crashcoursestan
http://www.twitter.com/realjohngreen
http://www.twitter.com/olsenvideo
When I was a kid I remember people talking about putting on sun tan lotion to help them absorb the sun's rays. Those days are over. Too much sun can be terrible for you.

Besides the fact that it increase the risk of skin cancer, the sun will age your skin and it'll make you look older too. Who want's that!?

Today we use sunscreen to protect us from the sun, but most of us are doing it wrong. How so? Sunscreen is the topic of this week's healthcare triage

Right off the bat before I say anything else I want you to hear that you absolutely should use sunscreen. Exposure to the sun's ultraviolet rays, both UV-A and UV-B causes damage to the skin which can lead to skin cancer. UV-B are rays the ones that cause most sunburn but UV-A rays, which penetrate deeper into the skin, cause the skin to wrinkle, and sag, and get leathery and all those other things we'd like to avoid. So use sunscreen!

Sunscreens with an SPF of 15 or higher really do protect your skin against the sun. And I know there was a recent study showing that women that didn't get enough sun have an overall higher mortality than women who do. I've seen all the articles on Facebook. So let's spend a minute talking about that.

To the research! Researchers followed almost 30,000 women in the Melanoma in Southern Sweden (or MISS) cohort. Over 20 years, 2545 of them died. Women who avoided the sun completely were twice as likely to die as women who sunbathed - scary, right?

First of all the absolute rate difference was 3% to 1.5%. Yes the headline said DOUBLED but that's a relative risk, and we all know the difference, right?

Next, even this study found that sun exposure was significantly linked to melanoma risk. That's still true.

Third, observational studies like this are gonna be confounded, meaning that there could be something they're NOT measuring that's causing the results. For instance, is it that hard to imagine that active people are more likely to be exposed to sun than totally sedentary people? And sedentary people can have a higher risk of death.

And a lot of the articles you all keep sending me on Facebook seem to be obsessed with the idea that this is somehow caused by vitamin D. This study had nothing to do with vitamin D. There's no measurement of vitamin D, no way to know if anyone is vitamin D deficient, no vitamin D variables at all. None!

Finally, this is not a randomized control trail. There's no causality here. There are, however, randomized controlled trials showing that sunscreen prevents melanoma and skin aging.

Sunscreen works. Use it! Comes in 2 types, organic and inorganic. Organic doesn't mean natural, like it does with food, it refers to the chemical definition; organic compounds are carbon-based, and that's true of sunscreens as well.

Organic sunscreens are absorbed into the skin. There they absorb the UV rays of the sun and then let the energy dissipate in more safe ways.

Inorganic sunscreen, on the other hand, are physical blockers. They sit on top of the skin and reflect UV rays away from the body.

The organic kind are much more common. but both are fine. The problem is that we don't use nearly enough. You should be using at least 1 ounce or the equivalent to 1 shot glass full. This is the official recommendation; you should use 2 mg of sunscreen per cm2 of your body, which equates to 2 finger lengths of product applied to all 11 areas of the body.

You also need to keep reapplying the stuff to make it work.

Recommendations say that you should put sunscreen on 30 minutes before you go out in the sun to let the ingredients bind to the skin. And then ideally, you should put on another application on 20 minutes later.

Studies show that this early reapplication is even better than waiting 2 hours, which is also a usual recommendation. Then you only need to reapply the sunscreen again if you go swimming, if you towel off, if you vigorously sweat, basically if you are outside in the sun.

I'd like to point out that it's somewhat ridiculous to expect people to follow recommendations like this. They just won't do it. If you stay at the beach all day that would mean you should use up most of your bottle of sunscreen - who does that?!

One could argue - and I'm happy to raise this argument - that the amount of protection promised on the bottle of sunscreen should be based on the actual amounts that people usually apply to their skin. Not the amount people used in the lab under unrealistic conditions.

Using average application amounts, the protection from sunscreen is probably half or less than half of what's listed on the bottle.

Moving on, if you believe what you see on TV you might think that you need SPF 1 gazillion to be protected. Is THAT so?

NO! First of all the difference between sunscreens of SPF 30, 45, 50 and 60 is 1.6% or less. Sunscreen with SPF 15 blocks approximately 94% of all incoming UV rays.

Sunscreen with SPF 30 block 96% of the UV rays. Sunscreen with SPF 40 block 97% of the rays.

Higher SPF sunscreen does block more UV rays, and they're better in that sense, but they're really not THAT much better, and it's not clear how much better they can get if you go above 50. Not that that's stopped companies from selling sunscreen SPF 100 and more.

Additionally, I know plenty of people who think that if they use SPF 60 instead of SPF 30 they only need half as much. That's just not true at all.

You've gained a few percentage points of protection at best and only if you're applying it in huge amounts over and over and over again. Ironically, besides being more expensive, the higher SPF formulations seem to come in smaller and smaller bottles, making using the correct amounts almost impossible. You'd probably be better off using the SPF 15 or 30 by the gallon and then applying it over again and again. THAT'S how you protect yourself from the sun. Stop worrying about the SPF and start worrying about how you put it on - that's how you do it right.

By the way, this episode of Healthcare Triage is sponsored by audible.com, a leading provider of premium digital and spoken audio information and entertainment on the internet.

Audible.com allows its user to choose the audio versions of their favorite books with a library of over 150,000 titles. We recommend The Sun Also Rises by Ernest Hemingway because it involves the sun. You can download a free audio version of The Sun Also Rises or another of your choice, at audible.com/triage.