Surprised at how sunscreen is tested? Take comfort that people are working to fix the problem

New technology being developed by researchers at RMIT, Australia, could be used to reduce reliance on human testers in sunscreen efficacy trials.

Current international practice involves using ultraviolet (UV) rays to test whether a product is effective. Of course, it’s that very UV radiation that causes the cancer that sunscreens are designed to provide protection against.

Human sunscreen testing therefore grapples with that ethical issue. It’s particularly challenging for countries like Australia that have a high incidence of skin cancer from UV exposure.

Explainer: How sunscreen is tested.

As the Australian Radiation Protection and Nuclear Safety Agency’s (ARPANSA) assistant director for UVR Exposure Assessment, Dr Stuart Henderson emphasises, it’s something that needs to change.

“It’s not the only way you can test sunscreens, but it’s the way that it’s made it into international standards,” explains Henderson. “The difficulty is in the way [sunscreen] interacts with the skin and the way it’s applied – it’s very difficult to simulate.

“That’s the reason behind human testing being considered the ‘gold standard’ and having made it [as the] international standard.

“Even though human volunteers are used to test the sunscreen, every little bit of UV exposure is adding to their chances of developing skin cancer, it’s a big health issue for the country.”

It’s why a project being developed at RMIT is promising: within a decade, the use of human subjects in sunscreen testing could be minimised, at least in Australia.

People are surprised when they learn how sunscreens are tested

When Professor Vipul Bansal first learnt of the international standard for sunscreen testing, he was too. But a new type of sensor technology being developed by his team at RMIT’s Sir Ian Potter NanoBioSensing facility (Bansal is the facility director), could provide a chance to get humans out of the lab.

“What we are trying to do is replace that skin with a skin-mimicking sensor that can provide a single response,” explains Bansal.

A prototype sensor developed by Bansal’s team changes colour when exposed to UV radiation. If they can modify the sensor to mimic human skin, then real skin may no longer be required.

While it’s still a way off – a decade is the timeframe Bansal is working to – it could solve the issue of exposing volunteer sunscreen testers to the very thing the products are meant to guard against.

First Australia, then the world?

If the sensor technology can be successfully adapted to substitute human for simulated skin, it would likely be trialled locally first.

From there, its expansion to the rest of the world would be outcome-reliant: that means having evidence that not only is the sensor an adequate replacement for human skin, but that the technology actually demonstrates sunscreen effectiveness.

It’s an opportunity with plenty riding on the outcome, which is why the project is being implemented without involvement from product manufacturers.

That level of independent rigour, says Bansal, will help build support in the technology. “The Australian government wants to develop this technique in collaboration with us,” he says. “So it’s an independently, regulatory-validated method.

“It doesn’t have any potential influence of the [sunscreen product] manufacturer, so once it comes out it will reduce the barrier to the market’s adoption.

“Once there is scientific evidence that the new method is as good or better than the existing, then other countries would start adopting it.”

Is simulated skin enough to replace the real thing?

It’s unclear, at this stage, of the extent to which sensor technology could replace a human subject in sunscreen testing processes. After all, a textured skin-like layer designed to respond as the real thing, still isn’t the real thing. And the sensor isn’t designed to test for the safety of the materials used to make this guardian goop – they would still need to be assessed. 

But what Henderson hopes is that at the least, sensor technology will help regulators avoid the current ethical issue of exposing people to UV.

“What we’re hoping is that we’ll take out the element of human testing that involves exposing people to ultraviolet radiation – it’s a known carcinogen, that’s what we want to get away from,” Henderson says.

“Purely from the UV side of it, that’s the aim.”