← What's That Rash?
What's That Rash?
Sunscreen spectacular: UV protection, SPF drama, endocrine disruptors
00:22:17
There have been many discussions this year about sunscreen, its effectiveness and its ingredients. Whil there are some unknowns, what we’re sure of is sunscreen’s ability to protect us from the sun’s ageing and cancer-causing rays. Norman and Tegan slip, slop, slap some questions about sunscreen: SPF scandal, endocrine disruptors and vitamin D concerns. References: How does sunscreen work? - Cancer Council Sunscreen: a brief walk through history We tested the SPF claims of 20 sunscreens. 16 failed - CHOICE TGA statement on CHOICE SPF sunscreen findings Safety Review of Seven Active Sunscreen Ingredients – July 2025 Daily sunscreen application and betacarotene supplementation in prevention of basal-cell and squamous-cell carcinomas of the skin: a randomised controlled trial Mineral vs chemical sunscreens Can your sunscreen expire? If you enjoyed this episode, check these out! Is there such thing as TOO much sun protection? We all need a daily dose of sunlight — but how much...
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- [00:02]
A
When the holidays start to feel a bit repetitive, reach for a Sprite Winter Spiced Cranberry and put your twist on tradition. A bold cranberry and winter spice flavor fusion Sprite Winter Spice Cranberry is a refreshing way to shake things up this sipping season, and only for a limited time. Sprite obey your thirst. ABC Listen, podcasts, radio, news, music and more. How wary are you of the amount of sun that you get each day, Norman?
- [00:35]
B
I'm reasonably aware of it. I mean, I've got olive skin, so I'm slightly less susceptible than Irish skin. But, you know, when I go on my bike in the morning, I make sure I'm well covered and the exposed areas are well covered with sunscreen.
- [00:48]
A
You're such a good man.
- [00:49]
B
Yeah, when I grew up in Glasgow, it wasn't such a big deal.
- [00:52]
A
Yeah, there's a lot of different things that go into that, but definitely Australia is the skin cancer capital of the world. Hopefully we can shift that to being the sunscreen capital of the world instead.
- [01:01]
B
But it has changed. I mean, I've got, you know, a Super 8 film of my middle brother when we were. Remember, I grew up in Scotland and we had a rare holiday in Italy and this shows him swimming around in a fountain with his back completely blistered with sunburn. I mean, that was what was tolerated a wee while ago.
- [01:21]
A
A mere wee while ago. Well, that is what we are talking about today. Not giant blisters on your brother's back, but sunscreen here on what's that Rash.
- [01:28]
B
The show where we answer the health questions that simply everyone is asking.
- [01:36]
A
This week. Norman, we have had so many different questions about sunscreen, quite literally everyone is asking about it that I'm going to talk you through the questions later. But I actually thought that we should start with just a bit of a primer on sunscreen and as a setup to the questions that I will deliver to you for you to answer in rapid fire form later. I think it would be useful to kind of start with like, what is sunscreen and how on earth does it actually work?
- [02:01]
B
Sunscreen is a technology that stops ultraviolet B and ultraviolet A light getting through to the skin. Ultraviolet B is the form of radiation that causes the burn and is also carcinogenic. But UVA doesn't cause the burn. But UVA is thought to go deeper under the skin and be much more potent in terms of cancer causation. So both are important. And sunscreen, broad spectrum sunscreens lock both UVA and uvb.
- [02:32]
A
How can something that is clear be Protecting us against light.
- [02:37]
B
Well, they're not all clear. So it depends on which sunscreen you use. If you use a mineral sunscreen with titanium dioxide or zinc oxide, that tends to be white, you know, you've got it on the skin, it's thick, it's a bit gunky.
- [02:52]
A
But some of those formulations are designed to disappear into the skin.
- [02:55]
B
So they have, over the years they've developed nanoparticle versions of the mineral sunscreens which are less obvious when you're wearing them. That's true.
- [03:04]
A
So sometimes, yeah, like you're saying, sometimes they are visible. They're literally blocking, physically blocking the light. But for those nanoparticle mineral sunscreens and for chemical sunscreens, how are they able to get rid of that light when they appear invisible?
- [03:19]
B
The mineral versions, zinc oxide and titanium dioxide, they absorb the ultraviolet light, but they also reflect it back. The non mineral sunscreens, some of which by the way, can contain some zinc oxide or titanium dioxide. But basically those other ones that are invisible are ones where the chemicals filter the UV light out.
- [03:42]
A
It is so interesting. With sunscreen. The thing as often surprises me whenever we sit down to do some WhatsApp rash research is how old and also how recent the history of sunscreen is. Like, people have known that the sun burns our skin for millennia. But then on the other hand, the link between sun exposure and skin cancer and the development of mineral based sunscreens is so recent, like just in the last century. It's really crazy how old and how recent this history story is here, but.
- [04:14]
B
It'S cultural as well. So the original use is thought to be nothing to do with sunburn, but to actually keep your skin white. Because even in regions where skin colour is brown or black, the less brown, the less black you are, the less prejudice you experience, because it was an.
- [04:34]
A
Indicator of where you worked or didn't work. So naturally, in a culture where working in the fields or working outside in the sun is considered to be less desirable, the complexion that goes along with that is seen to be less desirable. It's funny cause it swung back the other way. I'll tell you that story in just a second. But I was really interested to see the various ways that humans have attempted to protect themselves from the sun over the millennium.
- [05:00]
B
Go on, take us a walk through this history.
- [05:05]
A
So the oldest one that we, at least that I was able to turn up was naturally the ancient Egyptians, they put things like rice bran and jasmine on the skin. I'm not really sure how effective that was. That's sort of up to 5,000 years ago that we're talking here. A bit more recently than that. Two and a half, 3,000 years ago. The ancient Greeks used your favorite Mediterranean diet ingredient, Norman.
- [05:31]
B
Extra virgin olive oil.
- [05:33]
A
Extra virgin olive oil. They put olive oil on their skin to protect it from the sun. And I associate oil in the sun with, like, a tanning thing. It actually does.
- [05:43]
B
Yeah. It's a basting thing.
- [05:45]
A
Well, it actually does have an SPF. It's very low. But olive oil has an SPF rating of between 2 and 8, which isn't nothing.
- [05:55]
B
No, it's not nothing. It's close to nothing, but it's not nothing.
- [05:58]
A
It's not nothing. So that's interesting. The other thing that I loved was women of fair skin in Europe in the 1600s used these things. Have you heard of a Vizard before?
- [06:10]
B
This is not Steve Visard.
- [06:12]
A
Not Steve Vizard. It's a face covering made of velvet. You've got to look up a photo on the Internet. They look cooked. They just look like someone has a black oval over their face. Sometimes they've got eyes cut out of it, sometimes they don't. They were made of velvet. For some reason, I'm like, if you just want to shield your face from the sun, surely you could find a less uncomfortable fabric than just wearing an oval of velvet on your face.
- [06:36]
B
But they also used cosmetics that contained lead. You know, stain the skin white.
- [06:42]
A
Anyway. Just shimmying right through history here. Okay, this is something I wanted to ask you about, Norman. So there was A German doctor, Dr. Hammer of Stuttgart, who recommended the use of chemical sunscreens.
- [06:55]
B
The Hammer of Stuttgart.
- [06:56]
A
The Hammer of Stuttgart. He recommended chemical sunscreens and he used quinine, which stood out to me because I thought that quinine, at least when you take it orally, made you more sensitive to the sunlight.
- [07:08]
B
So the answer is yes. I mean, in fact, it was one of the first photosensitizers ever discovered. So I'm not sure Dr. Hammer was on a winner.
- [07:14]
A
Well, there you go. And then there was a different German physician, Dr. Paul Unner, who came up with a term that he called semenschaltkarsinom. What do you reckon that meant?
- [07:27]
B
Semen. Well, there are two meanings to the word semen. I'm assuming that they're talking about something naval, so sailors. And carcinom is presumably something to do with cancer. The bit in the middle, I'm not so sure.
- [07:40]
A
Sailor's skin. Carcinoma. Simonschalt. Carcinom. He was the first well, the first that we could find anyway to describe an association between sun exposure and skin cancer and that was in 1896. Cause that, that was the thing I was really interested about is, of course we've known for millennia that your skin burns in the sun because it happens so quickly afterwards. But I was wondering how long it would have taken us to make that association between long term sun exposure and that later cancer and turns out 1896.
- [08:10]
B
Yeah. Because you've actually got to have these observations of a reasonably large number of people over a significant space of time.
- [08:16]
A
And then coming to the little tease that I gave you before as to when it became popular to have slightly darker skin again, at least among some groups. Coco Chanel, credited with being the person to effectively invent sunbathing.
- [08:30]
B
Yeah. She was on a boat with her friend, Prince Jean Louis de Faussigny. Lucine.
- [08:36]
A
Oh, beautiful.
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B
On a boat in the Mediterranean.
- [08:38]
A
And the reason why tanned skin became sought after is really the same reason that pale skin was sought after previously. It's because it indicates what you do with your time. And instead of perhaps being indoors working in a factory, you have leisure time and you are outdoors on a boat in the Mediterranean. So either way, our skin colour has been a class indicator for a really long time.
- [09:01]
B
And then there was the glacier cream, because of course, people at high altitudes got a lot of sunburn.
- [09:07]
A
Yeah. Because you're getting less protection from the atmosphere, but also you're getting that glare off the glacier. I was, it turns out glacier cream, this cream that was invented in the 1960s, glacier creme. Glacier creme has roughly the same SPF rating as olive oil. It's 2.1.
- [09:25]
B
Yeah. Not, you know, you wouldn't go to town on that one anyway. You wouldn't go to the beach on that one, I should say.
- [09:30]
A
Let's just sort of fast forward a bit. The. The last thing that I really wanted to kind of call out was, well, two things. One, how recently it is that we've had SPF ratings that kind of mean something. It's from 80s and 90s we started to have the idea of SPF ratings 15, 30 and then up from there. The other thing that you should just.
- [09:51]
B
Explain what an SPF rating is.
- [09:52]
A
Yeah, sorry, go for it.
- [09:53]
B
This is a sun protection factor. So the factor is how many times more ultraviolet light you need when you've got one of these sunscreens on to cause early burning, early sunburn compared to having nothing on. So an SPF of 15 means that you need 15 times more time out in the sun to get some burning compared to no cream at all. Now that could be, you know, 15 times sounds great, but it could be the difference between 15 minutes and one minute. So it's not necessarily a notation of safety, but the idea is you want that SPF rating to be as high as possible.
- [10:33]
A
Right. So I mean, sunscreen equals good. I feel like that is the overarching theme here. Are there any other reasons that you wanted to call out?
- [10:42]
B
No, I think I'm done here. Have I missed something in my starter for 10 here? Well, and sorry, and just a little bit in the history is that they've refined the chemistry of sunscreens over the years. So they've got rid of things like para amino benzoic acid, which was there, which causes a lot of skin sensitization and other problems.
- [11:01]
A
That's what the PABA free means.
- [11:02]
B
PABA free. And you've now got sunscreens which do both UVA and UVB broad spectrum. And there's about six or seven chemicals that are common to a lot of different sunscreens.
- [11:15]
A
So now that we've sort of established sunscreen broadly equals good, let's go through some of these questions that we got from you, our beloved audience. First up, Norman and I am putting you on notice as usual. This is a rapid fire round. Some nuance may be lost in the process. Beth and Michael want us to talk about the sunscreen scandal. So this is the news story that came out earlier this year where Choice tested some of the top sunscreens in Australia to see how they advertised SPF related to their actual SPF. And almost all of them failed.
- [11:48]
B
Yeah, 16 failed. So what do we mean by failed? Well, if you were buying a sunscreen that said SPF 50, they didn't actually meet that standard of sun protection factor of 50. They were a lot less than that. Some of them were down incredibly low. There was a zinc skin screen which returned an SPF of 4 and that was cross checked in another lab and it came back as five. So essentially when they failed, they weren't meeting the SPF that they had on the label.
- [12:20]
A
And that was a real outlier, that one. There were a handful of them in the. There were a handful of them in the 30s. There were a couple of them in the 40s. I think what this story really highlighted is just how hard it is to know that you're getting what it says on the tin.
- [12:35]
B
So let me just give the caveat here, which is what I think the Therapeutic Goods Administration said. But I mean, they've got a problem here because these are therapeutic substances and they come under the regulatory egos of the Therapeutic Goods Administration. This has happened on their watch. Some of these sunscreens were tested by the same lab and the assumption is that the way they tested it was not satisfactory. Now, what the TGA said, and there is some truth to this, is that most of them came in over 20. And when you look at some of the Queensland research that's been done on sunscreens, they found that if you actually had an SPF of 16 or over, you still got significant protection. So it's not good. Even buying 50 and it's only a 24, for example, that's not great. But even a 24, you have been getting significant protection.
- [13:29]
A
So our next question comes from Kestrel. Kestrel's asking about hormone disruptors and says, I've been an avid sunscreen wearer my whole life. It seemed like a pretty easy decision. But then I had a baby once. She was past that first six months where they say not to use sun creams. I was expecting we'd just slather her with any of our well tested high UV protecting products. But then I started reading about hormone blockers and damage to coral and sea life from chemicals in sunscreen. Should we all be using zinc based physical sunscreen instead?
- [13:59]
B
So the story with endocrine disruptors is that the therapy good administration in July of this year did publish a review of the seven commonest chemicals in sunscreens. And the two that they pulled out for concern were homosalate or homosalate and oxybenzone, and that they did have some effect because they were absorbed through the skin and in animal studies seemed to have an effect which looked a bit like endocrine disruption. Now, the caveat here is that their margin of safety is based on using these sunscreens to the whole body 240 days of the year.
- [14:44]
A
Right.
- [14:45]
B
So they estimate that the chemicals that are used in sunscreens, assuming that you're mostly using them on your face and arms and probably not 240 days of the year, and that the concentration of homosylate or oxybenzone is low in the product, then the margin of safety is going to be much higher. But those are the two that they felt required regulation. Experts in the area take a pragmatic view of this and they say that these chemicals have been in products now for many, many years without any significant safety signal.
- [15:22]
A
Okay, so I'm curious, Norman. I just feel like this year you have been very switched on about endocrine disruptors. And so I'm surprised that you haven't brought this up.
- [15:30]
B
Paranoid.
- [15:31]
A
Paranoid Norman, you're stumbling through the parbor free. Paranoid Norman, talk to me about this.
- [15:37]
B
So like everything, it's risk versus benefit. Okay? I've changed over to glassware and as you say, cast iron cookware and so on based on no evidence. Effectively, you know, the PFAS is true. Well, it's not quite no evidence. The pfas.
- [15:52]
A
I knew it was a flex. I knew all this time it was just a giant flex. It wasn't health related at all.
- [15:57]
B
Yeah, it was just neurosis. But the, you know. So you're doing it on the precautionary principle. The difference with sunscreen is that we actually know the damage that sun does and we know that sunscreen blocks it. And therefore sunscreen would have to be really dangerous for you to say I'm not going to have it. And there's no evidence of things being really dangerous, particularly the way we use it commonly. So even those two substances we talked about, homosolate and oxybenzone, at the level that they are being used, they're not really much of a worry either. So I'm much more relaxed about sunscreen.
- [16:32]
A
Okay, alright, that's good. Your justification stands.
- [16:35]
B
The other aspect of sunscreen is there's probably not a sunscreen manufacturer in the country who says that this is the only form of protection you should take. So if you've got a child, they should be wearing a rashi. They should be wearing clothes that are proven to block sunlight, not all clothes do. And so the child is almost fully covered. And it's just the child's head and neck and hands and you know, their feet that are covered and that is the safe way to go. And playing under a rated umbrella. So you've got shade as well.
- [17:10]
A
Yep. Slip, slop, slap and slide on some sunglasses and seek shade. It's all, it's, it's only 1/5 of the campaign on how we stay safe in the sun. Well, going to our next question, Sasheena has asked us whether sunscreen blocks vitamin D. Especially in the context of people.
- [17:25]
B
With darker skin, they probably block it a little bit. But most people who are interested in vitamin D and sun say that in a practical sense, none of us use sunscreen to the extent that it's significantly going to block vitamin D. So we're imperfect in our use. And I suppose if you were perfect and you're doing it 365 days a year, then you've got a problem. So most cancer councils now on their websites will give you the sort of sun exposure that you need to make sure that your vitamin D levels are high and it's head and shoulders for a few minutes a day, depending on.
- [18:04]
A
The season and depending on your skin.
- [18:06]
B
Colour and depending on your skin color.
- [18:09]
A
Well, we actually answered this question back in January 2024. You can listen back to that episode of Whatsat Rash. It's called Is there Such Thing as Too Much Sun Protection? And also our wonderful Whatsat Rash producer Shelby Traynor also wrote an article for the ABC News website called We All Need a Daily Dose of Sunlight, but how much? So if you want to do some further reading, we'll point you in that direction.
- [18:30]
B
Yeah. Just in our show notes, Rob is.
- [18:32]
A
Asking, as we pull out tubes of previous year's sunscreen, how concerned should we be about using sunscreen that's past its use by date?
- [18:41]
B
You should be reasonably concerned. So it's not just the expiry date. Have you left it in the glove box in your car? And it's been boiling away there and the car while you're at the beach? It could be within your expiry date, but you've actually overheated it and when you squeeze it out, it looks a bit watery and it's not the nice creamy consistency that you would expect for sunscreen. Chuck it out and buy another one. A lot of this is about the associated chemicals that go into sunscreen to preserve it. And you should. Yes. Follow the expiry dates.
- [19:14]
A
One more question. This one's from Linda. Should sunscreen be removed from your skin at the end of each day? There are many times I have not and I don't know if it's important.
- [19:25]
B
Well, the answer is. We don't know the answer to that question. We've had a previous. What's that rash on? Can you get away with skipping your daily shower? And you should refer back to that again. The link will be in our show notes. The extent of absorption of sunscreen is limited. So, for example, mineral sunscreens have very limited absorption into the body. The ones that are invisible with these seven chemicals that we talked about, broad spectrum sunscreens, those ones do get absorbed into the layer underneath the skin, but once it's there, probably showering doesn't make a lot of difference and then they just deteriorate or they're taken out by metabolism. So I'm not sure that it's that important to remove it at the end of the day.
- [20:06]
A
I'm thinking about days that I'm in the sun and I'm wearing a lot of sunscreen. It's not the sunscreen's fault that I need to shower at the end of the day. I've been out in the sun. I'm pretty sweaty. Washing it off is probably not a bad idea.
- [20:16]
B
Bottom line here is we're coming into summer.
- [20:19]
A
Slip, slop, slap, slip, slop, slap, seek, slide. Stay safe. Well, thank you all so much for your questions. It has been a lot of fun going down sunscreen lane today. You can email your questions to us anytime. Our email address is thatrashbc.net au and.
- [20:35]
B
Keep the olive oil for the Mediterranean diet.
- [20:39]
A
So this is usually the part of the show where I would read our mailbag. Norman. But I want to do something different today because we are now well into the holiday. I would love people to send us their the interesting health claims they have been hearing at Christmas parties and family dinners.
- [20:59]
B
Yeah. And how much disagreement there has been about it.
- [21:03]
A
Yeah. I want to hear your interesting relatives and colleagues claims around health that you think you would like us to have a look at in the new year. I think we could have a lot of fun with this.
- [21:12]
B
Yeah. Your uncle Fred on COVID vaccine. Let's hear it.
- [21:15]
A
Just gives it to us that rashbc.netu is where you should send those beefs and questions and we will have a fun digging into that mailbox after Christmas.
- [21:25]
B
See you then.
- [21:26]
A
See you then.