There's a notable absence of studies showing evidence of harm after 40 years of widespread use 😉 Beyond that, the EU safety assessments are very reassuring - this was cut from the final piece since I could probably write 50,000 words on sunscreen, but the allowed limits are pegged to extremely small effects in animals e.g. even if you applied 220% oxybenzone sunscreen all over, every day, you still shouldn't have enough to cause a reduction in spermatocytes in a male fetus you were carrying. I have an article on my website that delves into this in more detail called "US Sunscreens Aren’t Safe in the EU? The Science"
I do love UV protective clothing! But sunscreens do have their place as well, for places where it's impractical to wear clothing (face, ears and hands, mostly). Aussies are big fans of the rash vest - we have some pretty fashionable designs now, and I love never missing a spot on my back!
The popularity of rash guard-style swimwear is such a lifesaver as a parent with young kids! If I had to slather every inch of them, we probably just wouldn’t go swimming that often.
These are great answers, but most people spend a ton of time indoors these days. It would be helpful to note when sunscreen is actually needed: i.e. before going outside for 10 minutes, an hour, or three hours? I am usually in the sun for a total of half an hour a day, do I need to spend a fortune coating myself every morning? Also, when does the effectiveness of the sunscreen wear off?
This is a complicated question, I've had to tackle aspects of this over multiple articles 😅 In short:
For skin cancer protection in light skin, Australian guidelines recommend using the full suite of sun protection (including sunscreen) if outside for more than an hour total (including incidental exposure) at UV index 3 or higher. For darker skin tones (Fitzpatrick 3 or above) the advice is a bit more nuanced...
If you're indoors, you only really need sunscreen if the sun is directly shining on you
When it wears off depends on how much activity you're doing
I am also wondering this. In addition, is sunscreen only needed when the UV Index is at a certain level, or should I truly be reapplying every single time I leave my house to be outside for more than 5 minutes?
My question (which I never see addressed in Consumer Reports or elsewhere)...how well do sunscreens retain their effectiveness in the bottle? If I have a half-used bottle of sunscreen from last summer, or two (or more) summers ago...is it still good?
In addition to what Natalie said, the expiry date assumes storage under ideal conditions - if it's been in the sun, in a hot car etc, I'd buy a new bottle.
In the US at least, FDA regs require sunscreen to last for at least 3 years in the bottle. I suspect most people use them up (or just lose the bottle) before that, which might be why it’s hard to find other data.
Yaaaaay, you worked with Dr Wong on this! So glad you did, she’s fabulous! I’m not on instagram anymore; her videos are the some of the ones I miss the most.
Thank you! I try to also crosspost my short videos to YouTube and TikTok 😊 I also do a roundup on my Substack newsletter (although I'm really not good at remembering to update!)
I had the same thought Pam! YLE and Dr Wong have been my top 2 go-to science/health communicators for years and I'm totally fangirling on this collab 😍
If you take any medication as your pharmacist to look up whether it causes photosensitivity. Many antidepressants do.
One of the considerations in sunscreen choices and use is individual vulnerability. I lived in high altitude desert for decades. I could get a real sunburn in 15 minutes. I am fair but even dark-skinned people can burn.
I have worn sunsleeves and a broad-brimmed hat outdoors for years. I have sun balaclavas and a hood. For a time I even had a golfer’s nose guard. I have several sun protective long sleeve shirts. In the summer I got tan even while wearing all of the above. Ten year old sun shirts and sleeves still work!
Agree that individual circumstances are a huge consideration! The latest Australian sun exposure guidelines take into account skin tone, along with UV index which has been in the guidelines for over 20 years 😊 It's a pity the rest of the world have been a bit slow to adopt them...
Quite a few skincare ingredients also cause photosensitivity! Mainly chemical exfoliants (alpha hydroxy acids and the like). Learned that the hard way once. 😬
Thank you for this excellent piece. You write: "They confirmed what leading coral scientists stated when the original 2015 study was published: the impacts of sunscreens pale in comparison to far more significant stressors, like warming weather." As an avid snorkeler and nurse, I take a harm reduction approach. My snorkeling of the Great Barrier Reef, the Caribbean, and, most recently, Indonesia, has shown me that the reefs are being stressed and sometimes destroyed by global warming that is heating up the seas. Add additional stressors such as may occur from the use of oxybenzone, avobenzone, and octinoxate could accelerate their demise, I fear.
This was cut from the final version of the article, but the National Academies report actually found that zinc oxide is more harmful to marine organisms than a lot of chemical sunscreens, so even with a harm reduction approach, switching to mineral sunscreens doesn't make sense. Add this to the environmental impacts of zinc mining - mineral sunscreens are really not the environmentally friendly option! My friend Jen Novakovich of The Eco Well has some great posts on this - she's actually doing a PhD on environmental misinformation 😊
Yes, the best sunscreen for people who are going to be snorkeling or swimming in the vicinity of coral reefs is NO SUNSCREEN! Instead, cover up using a dive skin or a long sleeved rash guard plus full length swim pants, combined with a Lycra or neoprene hood! Not only does that protect you from sunburn, it protects you from stinging organisms such as fire coral or sea lice or abrasions from accidentally scraping against rocks. If when you are snorkeling or swimming the only part of your body that is left uncovered by UV protective swimwear is your face you are going to get much in the way of a sunburn, because your face is facing down into the water almost all the time when you are in the water.
“Both types of sunscreen largely work by sitting on the skin's surface, where they absorb UV radiation and convert it into heat.”
Well TIL how sunscreen actually works! That did make me wonder, mostly academically - does that mean sunscreen makes our skin feel hotter? Or is it a small enough change that we don’t really notice?
This is very helpful. I have wondered about the difficulty of getting good effectiveness studies. It would also be handy to have studies that showed no other harms to the body from daily sunscreen use--I can feel some fear, knowing that things on the skin get absorbed into the rest of the body. Thanks for this assessment of the science--my dermatologist would thank you also.
What about mineral sunscreens that have no white cast? Are they as effective as the ones with a white cast? I found a mineral sunscreen that with a bit of rubbing in has no white cast.
Alba Botanical sheer mineral broad spectrum spf 50. Not sure how much I apply but when it’s on my skin it’s white and as I rub it in the whiteness disappears.
It has 24% zinc oxide which makes me suspect you might not be applying enough (or you might just be relatively pale-skinned!) - it's recommended that you apply one teaspoon per limb, and 1/4 teaspoon for your face alone to get the protection on the label. It also contains an SPF booster Butyloctyl Salicylate - this is essentially a chemical sunscreen (very similar structure to octisalate), so it's leaning on chemical sunscreen technology to achieve its protection rather than just mineral actives 🤨
Do sunscreens actually expire on the date listed on the bottle/tube/can? If the sunscreen has been stored inside, like my non-sport daily face sunscreens, can they be used beyond the date listed? How much longer? A couple months? 6 months? A year?
I expect that any sunscreen that has spent time in extreme temps, such as at the beach or in a car, to expire by the date listed.
There's a notable absence of studies showing evidence of harm after 40 years of widespread use 😉 Beyond that, the EU safety assessments are very reassuring - this was cut from the final piece since I could probably write 50,000 words on sunscreen, but the allowed limits are pegged to extremely small effects in animals e.g. even if you applied 220% oxybenzone sunscreen all over, every day, you still shouldn't have enough to cause a reduction in spermatocytes in a male fetus you were carrying. I have an article on my website that delves into this in more detail called "US Sunscreens Aren’t Safe in the EU? The Science"
I'm glad you included what we might call cloth sunscreens, which have no known harmful effects and are very easy to apply evenly.
I do love UV protective clothing! But sunscreens do have their place as well, for places where it's impractical to wear clothing (face, ears and hands, mostly). Aussies are big fans of the rash vest - we have some pretty fashionable designs now, and I love never missing a spot on my back!
The popularity of rash guard-style swimwear is such a lifesaver as a parent with young kids! If I had to slather every inch of them, we probably just wouldn’t go swimming that often.
My family used to go river rafting in lightweight muslin suits - no sunburn.
These are great answers, but most people spend a ton of time indoors these days. It would be helpful to note when sunscreen is actually needed: i.e. before going outside for 10 minutes, an hour, or three hours? I am usually in the sun for a total of half an hour a day, do I need to spend a fortune coating myself every morning? Also, when does the effectiveness of the sunscreen wear off?
This is a complicated question, I've had to tackle aspects of this over multiple articles 😅 In short:
For skin cancer protection in light skin, Australian guidelines recommend using the full suite of sun protection (including sunscreen) if outside for more than an hour total (including incidental exposure) at UV index 3 or higher. For darker skin tones (Fitzpatrick 3 or above) the advice is a bit more nuanced...
If you're indoors, you only really need sunscreen if the sun is directly shining on you
When it wears off depends on how much activity you're doing
This article covers it with links to longer pieces, although I haven't managed to tackle the skin tone guidelines yet! https://labmuffin.com/answering-almost-all-your-sunscreen-questions-with-video/
Great article thanks! It's good to get info from someone who isn't a sunscreen manufacturer 😊
I am also wondering this. In addition, is sunscreen only needed when the UV Index is at a certain level, or should I truly be reapplying every single time I leave my house to be outside for more than 5 minutes?
My question (which I never see addressed in Consumer Reports or elsewhere)...how well do sunscreens retain their effectiveness in the bottle? If I have a half-used bottle of sunscreen from last summer, or two (or more) summers ago...is it still good?
In addition to what Natalie said, the expiry date assumes storage under ideal conditions - if it's been in the sun, in a hot car etc, I'd buy a new bottle.
In the US at least, FDA regs require sunscreen to last for at least 3 years in the bottle. I suspect most people use them up (or just lose the bottle) before that, which might be why it’s hard to find other data.
Thank you so much for the reply, Natalie! This is very helpful.
Yaaaaay, you worked with Dr Wong on this! So glad you did, she’s fabulous! I’m not on instagram anymore; her videos are the some of the ones I miss the most.
Thank you! I try to also crosspost my short videos to YouTube and TikTok 😊 I also do a roundup on my Substack newsletter (although I'm really not good at remembering to update!)
Squeeeeee! I do YouTube! Will check it out!
I had the same thought Pam! YLE and Dr Wong have been my top 2 go-to science/health communicators for years and I'm totally fangirling on this collab 😍
If you take any medication as your pharmacist to look up whether it causes photosensitivity. Many antidepressants do.
One of the considerations in sunscreen choices and use is individual vulnerability. I lived in high altitude desert for decades. I could get a real sunburn in 15 minutes. I am fair but even dark-skinned people can burn.
I have worn sunsleeves and a broad-brimmed hat outdoors for years. I have sun balaclavas and a hood. For a time I even had a golfer’s nose guard. I have several sun protective long sleeve shirts. In the summer I got tan even while wearing all of the above. Ten year old sun shirts and sleeves still work!
Agree that individual circumstances are a huge consideration! The latest Australian sun exposure guidelines take into account skin tone, along with UV index which has been in the guidelines for over 20 years 😊 It's a pity the rest of the world have been a bit slow to adopt them...
Quite a few skincare ingredients also cause photosensitivity! Mainly chemical exfoliants (alpha hydroxy acids and the like). Learned that the hard way once. 😬
Thank you for this excellent piece. You write: "They confirmed what leading coral scientists stated when the original 2015 study was published: the impacts of sunscreens pale in comparison to far more significant stressors, like warming weather." As an avid snorkeler and nurse, I take a harm reduction approach. My snorkeling of the Great Barrier Reef, the Caribbean, and, most recently, Indonesia, has shown me that the reefs are being stressed and sometimes destroyed by global warming that is heating up the seas. Add additional stressors such as may occur from the use of oxybenzone, avobenzone, and octinoxate could accelerate their demise, I fear.
This was cut from the final version of the article, but the National Academies report actually found that zinc oxide is more harmful to marine organisms than a lot of chemical sunscreens, so even with a harm reduction approach, switching to mineral sunscreens doesn't make sense. Add this to the environmental impacts of zinc mining - mineral sunscreens are really not the environmentally friendly option! My friend Jen Novakovich of The Eco Well has some great posts on this - she's actually doing a PhD on environmental misinformation 😊
Yes, the best sunscreen for people who are going to be snorkeling or swimming in the vicinity of coral reefs is NO SUNSCREEN! Instead, cover up using a dive skin or a long sleeved rash guard plus full length swim pants, combined with a Lycra or neoprene hood! Not only does that protect you from sunburn, it protects you from stinging organisms such as fire coral or sea lice or abrasions from accidentally scraping against rocks. If when you are snorkeling or swimming the only part of your body that is left uncovered by UV protective swimwear is your face you are going to get much in the way of a sunburn, because your face is facing down into the water almost all the time when you are in the water.
Great piece! Hit all the big points so well! Thank you!
“Both types of sunscreen largely work by sitting on the skin's surface, where they absorb UV radiation and convert it into heat.”
Well TIL how sunscreen actually works! That did make me wonder, mostly academically - does that mean sunscreen makes our skin feel hotter? Or is it a small enough change that we don’t really notice?
No real difference! I did an experiment where I looked at different sunscreens through a thermal camera - the amount of heat was undetectable, probably because skin is full of water which is a great heat sink https://labmuffin.com/do-we-need-to-worry-about-heat-from-sunscreens-with-video/
Neat!
Just here to say how much I adore Dr. Michelle Wong. This is so helpful.
Thank you!
This is very helpful. I have wondered about the difficulty of getting good effectiveness studies. It would also be handy to have studies that showed no other harms to the body from daily sunscreen use--I can feel some fear, knowing that things on the skin get absorbed into the rest of the body. Thanks for this assessment of the science--my dermatologist would thank you also.
What about mineral sunscreens that have no white cast? Are they as effective as the ones with a white cast? I found a mineral sunscreen that with a bit of rubbing in has no white cast.
Which one and how much are you applying? I haven't heard of one without white cast yet - but I'm open to the concept in theory...
Alba Botanical sheer mineral broad spectrum spf 50. Not sure how much I apply but when it’s on my skin it’s white and as I rub it in the whiteness disappears.
It has 24% zinc oxide which makes me suspect you might not be applying enough (or you might just be relatively pale-skinned!) - it's recommended that you apply one teaspoon per limb, and 1/4 teaspoon for your face alone to get the protection on the label. It also contains an SPF booster Butyloctyl Salicylate - this is essentially a chemical sunscreen (very similar structure to octisalate), so it's leaning on chemical sunscreen technology to achieve its protection rather than just mineral actives 🤨
Thank you!
I am fair skinned.
I’m sure I apply more than 1/4 teaspoon to my face.
Thank you so much for this. It's super helpful.
Excellent, thank you.
I would truly like to know how to tap into the grey market that was mentioned. Anyone know how?
Skincare forums and influencers often discuss retailers 👀
Thanks!
Do sunscreens actually expire on the date listed on the bottle/tube/can? If the sunscreen has been stored inside, like my non-sport daily face sunscreens, can they be used beyond the date listed? How much longer? A couple months? 6 months? A year?
I expect that any sunscreen that has spent time in extreme temps, such as at the beach or in a car, to expire by the date listed.