11 Things You Thought You Knew About Sunscreens | Dr Ankit
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Transcript with References
I forgot to use sunscreen before I left the house but I’m already outside. I’ve got sunscreen in my car but I won’t be able to wait for 20 minutes for the sunscreen to dry. Is there any point in using sunscreen at all? Hmm what do you think Pingu?
Hey guys welcome to DocUnlock where we help you learn more about your body so that you can make better decisions about your health. Today Pingu and I are going to help you learn about sunscreens. We’re going to answer some common questions and also bust some myths as we go. Let’s get cracking!
Q1: I don’t need to use sunscreen all the time.
So this one’s true. When the UV index is more than 3, that’s when it’s recommended to use sunscreen (Cancer Council Position Statement 2016).
Q2: Sunscreen shouldn’t be used for babies
So this one is true. Kids less than six months of age tend to have very immature skin so when you put sunscreen on them, there is a possibility that the ingredients in sunscreens can irritate their skin (Skin Cancer Foundation USA 2012). So to protect young babies from sun damage, the best way is to hang out in the shade or use UV protective clothing.
Q3: Sunscreen doesn’t work unless you’ve waited for 20 minutes
So this is an awesome question and something that I’ve actually thought about. In theory, technically, sunscreen is ready to go straight out of the bottle. The ingredients don’t need to have anything done to them for them to protect you from UV.
But the reason why manufacturers talk about this twenty minute rule, is because the sunscreen works best when it’s applied evenly and there is a dry even film on your skin. But that doesn’t mean that even if the sunscreen hasn’t had that time to dry, that it’s providing no protection. It’s just providing less effective protection.
So if you’re outside and you’ve forgotten your sunscreen, and you’ve got some in your car. Go ahead, use it. Because any amount of sunscreen is going to be better protection than no sunscreen at all.
Q4: Physical Sunscreens don’t need to be re-applied
Question number four, physical sunscreens don’t need to be re-applied. Well this one’s clearly false but I can understand why people may ask this question.
The reason why this question comes up is because there is this understanding that the ingredients in chemical sunscreens do breakdown when they’re exposed to UV. But it is thought that the physical sunscreens like zinc and titanium based sunscreens, well those ingredients don’t break down.
But the issue is, is that, reapplying sunscreen has got nothing to do with the breakdown of the actual ingredients. It’s because sunscreen rubs off your skin or drips off in the sweat. So it’s not because it’s actually breaking down that you need to reapply. Regardless of the sunscreen ingredient, zinc, titanium, chemical sunscreen, you still need to re-apply regularly to get the best effect.
Q5: Ingredientes from chemical sunscreens are absorbed and cause hormone problems
Again this is such an awesome question because it has sort’ve a half half answer, half true half false. So first thing to get out of the way is that physical sunscreens, those with zinc and titanium, don’t have any absorption into the body (TGA 2017). None at all. It just sits on the skin and doesn’t pass through the epidermis. But the ingredients in chemical sunscreens do have some absorption. In fact I think there’s a study, which had 32 people, and they applied sunscreen for a week (Janjua NR et al. 2004). The researchers took samples of urine and blood, and found there were detectable levels of sunscreen.
But the thing is that absorption is not the same as having a biological effect. So in that same study, when the researchers tested the hormone levels, they were exactly the same as before, no change. So just because there is some absorption of chemical sunscreens, doesn’t mean it’s having any harm for the body.
There’s another study that’s often quoted on the internet which is a rat study (Schlumpf M et al. 2001). So in this study, rats were actually fed astronomical doses of these sunscreen ingredients and they found that the womb size, or the uterus size increased in these rats.
There was a subsequent paper which discussed this study, and actually calculated how much sunscreen you would need to use to get that same level (Wang SQ et al. 2011). And they calculated that with regular sunscreen use, humans would need to apply sunscreen for something like 277 years to get the same dose. So again, not really relevant to what we’re talking about because we’re just not using sunscreen in that kind of dose range.
But if you are worried about hormone effects from sunscreens, the simple solution is to use physical sunscreens, the ones with zinc or titanium, because they don’t have any absorption at all so nothing to worry about.
Q6: Makeup protects you from the sun
Well, Pingu and I don’t know much about makeup, because we’re ruggedly handsome as it is.
But there is some truth to this. Foundation makup especially can provide some sun protection but it’s usually anywhere up to SPF four and five, which is not usually enough for most people (Wolverton SE 2012). There are some makeup products which include up to SPF fifteen sunscreen ingredients so that might be a good choice. Just remember that some of those cosmetics don’t have broad spectrum protection. So if you can find a cosmetic makeup, like a foundation, which is broad spectrum, that’s going to be better than UVB only protection.
Q7: Sunscreens can cause heat burns
Well this one’s definitely a myth. Well it’s true that sunscreens have these ingredients, which convert UV light into heat. I mean the UV light that’s absorbed has to go somewhere. But this is no where near as much heat as is required to get actual heat burns. So, this one’s clearly false.
Q8: I can’t use sunscreens because I am allergic to them
So this can be true for some people. People can react to the fragrance, sometimes the preservative, or even the sunscreen ingredient. The rate of this is actually quite low. So one study looked at about 24 thousand people, and found a one percent rate of allergic reactions to sunscreens (Warshaw EM et al. 2013). But if you have had an allergy to sunscreens, try using a physical sunscreen, with titanium and zinc, that minimises preservatives and fragrances because these tend to be better for sensitive skin.
Q9: Glass blocks UV so I don’t need to use sunscreen
Pingu the next one is, glass blocks UV so I don’t need to use sunscreen. So this one’s a myth. I showed you in my Vitamin D video how glass blocks UVB, but doesn’t block UVA (Butler ST 2013). So if you’ve got an office desk right next to the window, or you’re going for a long car ride, then using a broad spectrum sunscreen to protect yourself from UVA, is definitely worth your while.
Q10: Using sunscreen causes Vitamin D deficiency
This is a super interesting one. So, in theory, when sunscreens are used exactly in perfect experimental conditions, they block pretty much all UVB, and so in theory, that would lead to Vitamin D deficiency (Faurschou A 2012).
But here’s the kicker, when they did trials to compare Vitamin D levels in real world use of sunscreens, they found that sunscreen actually had no effect on Vitamin D (Marks R et al 1995, Norval M et al. 2009, Springbett P et al. 2010). And there might be a few reasons for this. The ones that come to mind is that, in real life, you don’t actually use as much sunscreen as you need to, to completely block UV. And also, you don’t tend to re-apply frequently enough.
So the fact that the skin is able to make Vitamin D very quickly, means that even with sunscreens, there’s still going to be enough UV around for your skin to be able to make enough Vitamin D. So definitely a myth, sunscreens don’t in themselves cause Vitamin D deficiency.
Q11: Using sunscreen doesn’t actually protect people from melanoma
So I don’t know where this one came from, but it’s clearly false. In fact there was a very important randomised trial that found that sunscreens protect from invasive melanoma, by seventy three percent (Green AC et al. 2011). That’s huge. So definitely use sunscreens to protect yourself from melanoma. I will say that there are some forms of melanoma which are not related to UV, but that’s very rare. Ninety five percent of melanomas are related to sunburns and UV.
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