Ruben Meerman
Aussie's love the sun and I'm no exception, but after 30 years of surfing, I'm starting to wonder what's all that exposure to the sun been doing to my skin? 

Prof Michael Kimlin
The biggest thing that we know the sun does to our skin - specifically UV exposure to our skin - is increase our risk of skin cancers. 

NARRATION
And it's the UV that's affecting the appearance of your skin. 

Prof Michael Kimlin
UVA radiation is more responsible for this photo-ageing - that is wrinkling, premature sagging of the skin - where UVB, we are very sure that it actually causes things like sunburn, skin cancers and risk of other skin-related disorders. 

Ruben Meerman
So, what affect has all that UV had on MY skin? 

Prof Michael Kimlin
What this machine allows us to do is look at excessive pigmentation as a by-product of sun exposure. So the body's defence mechanism when we have exposure to sunlight is to produce pigment. Well, here's your standard photograph that we took. This is showing what's happening on the surface of your skin. Now we're going to have a look underneath your skin. OK. 

Ruben Meerman
(Gasps) Oh, my goodness. 

Prof Michael Kimlin
So the thing that I see first off is these pigmentation points all through your face, but evenly distributed from your forehead down to your chin. It shows me that this is actually chronic sun-exposure, lifetime sun-exposure. The other thing is looking at what we call 'photo-ageing' - premature ageing due to sun-exposure - and the classic point that I can show you here is actually these wrinkles that I can see on your forehead, also around your eyes and even started in the corner of your mouth. 

NARRATION
Professor Kimlin ran this same test on a large sample of volunteers. 

Prof Michael Kimlin
The key thing that we found was that exposure at very low levels and at early life is actually quite important for imprinting this damage that we see in our skin. So our targeted health campaigns on protecting young people's skin is actually more important than ever. 

NARRATION
Sunscreens are a major part of the campaign to protect our skin, and they fall into two main classes - those lotions based on organic UV filters and those containing metal oxides. 

Associate Prof Paul Wright
This second class block out the full range of ultraviolet A and B damaging rays, so it's much more advisable to be using a sunscreen that has the metal oxides. 

NARRATION
In this lab at RMIT University, skin cells are exposed to a dose of ultraviolet light, both on their own and with the addition of extremely small particles of metal oxides called 'nanoparticles'. So here are the results. What did you find? 

Associate Prof Paul Wright
Well, as you can see in the first panel here, this is what normal human skin cells look like in culture, and they're flat and spread out. But if you expose them to ultraviolet light - here on the right side - a day later, you can see that many of them are lifted off and died and the rest have rounded up. So this is enough UV dose - similar to that from the sun - that can cause skin cell damage. So you really need to protect against that. 

Ruben Meerman
Right. 

Associate Prof Paul Wright
This time, we added the nanoparticles, and, as you can see, there's a lot of live cells there - they're much like the normal cells. So the nanoparticles have been protective. 

NARRATION
Some people have concerns that the nanoparticles in the sunscreen could be a health risk. 

Prof Brian Gulson
We were trying to determine whether or not the nanoparticles that are in the sunscreen penetrate the skin and then finish up in blood and urine or get into the body. 

NARRATION
The researchers took 20 volunteers to the beach and applied sunscreen to their backs twice a day for five days. 

Prof Brian Gulson
What we found was that small amounts of zinc from the zinc oxide in the sunscreens got through the skin and finished up in the blood and urine. The important thing is, though, that the amounts were really quite tiny. They were about a thousandth of the amount of zinc that's floating around in our body. 

NARRATION
One surprising result was that the zinc levels in the blood continued to increase after they stopped applying the sunscreen. 

Prof Brian Gulson
So that was out to 11 days, and we only applied the sunscreen for five days. So, what we need to do now is do a longer-term study, probably over three weeks, with titanium dioxide, and with some people with compromised skin - maybe eczema or something like that. 

NARRATION
So, what happens to the nanoparticles that DO make it through the skin? 

Associate Prof Paul Wright
The immune system is responsible for getting those sort of particles out of your body, so what we did is take human immune cells, exposed them to nanoparticles, and we went to the Australian Synchrotron to see if we could visualise these nanoparticles inside the human immune cell. So that's what this picture shows on the left. And you can see that the nanoparticles are there with the human immune cell. We then used electron microscopy, and this picture on the right shows that after a couple of layers have been taken off the immune cell, the little black dots inside the cell are intact nanoparticles. So the human immune cells are doing the job that they're supposed to do. They can clear any nanoparticles like this that could get through and perform their normal function. 

NARRATION
Research into sunscreens is ongoing, but what is beyond doubt is the high risk of skin cancer and the damage that can result from exposure to ultraviolet light. 

Prof Michael Kimlin
Look, to be honest, the best way to protect your skin is through sun-avoidance. That is truly the best way to protect your skin. But unfortunately, we live in such a beautiful climate in Australia, we can't spend all day indoors, so I think we should start thinking about a combination of protection strategies - so looking at sun-avoidance combined with sun-protection with clothing, and also sunscreen as a last line of defence. 

Ruben Meerman
So the message is clear and you've heard it before - if you want to protect your skin from damage, don't expose it to too much sun.

STORY CONTACTS

Professor Michael Kimlin 
Radiation Epidemiologist
Institute of Health and Biomedical Innovation
Queensland University of Technology

Associate Professor Paul Wright 
Nano Safety Researcher
Toxicology Key Centre
RMIT University

Emeritus Professor Brian Gulson 
Environmental Scientist
Macquarie University