Sunscreen tests are riddled with problems you probably never considered: ScienceAlert

As summer approaches, we need to start remembering to put on sun-protective clothing, apply sunscreen, put on a hat, seek shade if possible, and put on sunglasses.

When it comes to sunscreen, we all know we need to wear it to protect ourselves from the harmful effects of ultraviolet (UV) rays, which can cause skin cancer.

But what about the sun protection factor, known as SPF, that we see on our sunscreen bottles? It indicates the level of protection – but is it always what it says and how is it actually tested?

Risking human health for SPF testing

Although there have been cases of sunscreens not meeting their SPF claims, this is the exception and not the norm.

In Australia, we can take comfort in knowing that these products are strictly regulated to ensure that they are safe and meet their claimed SPF rating, according to current SPF testing methods.

However, problems arise when it comes to How? ‘Or’ What sunscreens are tested for their SPF index. Most people don’t know that the SPF value of their sunscreen bottles is determined by human testing.

Ultimately, that means we’re risking people’s health to test the effectiveness of our sunscreens – and we need to change that urgently.

How is SPF sunscreen tested?

Once a sunscreen formulation has been developed by a manufacturer, it must be tested to ensure that it contains only approved ingredients and ultimately does what it says. .

All sunscreen products available in Australia are tested to the Australian Standard to determine SPF. It’s great and it ensures safety and quality for the consumer – but the problem lies in the way these tests are carried out.

Currently, testing sunscreens on humans is the approved international standard for evaluating a sunscreen’s level of UV protection. These tests involve volunteers wearing strictly defined amounts of sunscreen and being exposed to artificial solar UV rays.

Performance is measured by determining the time it takes for erythema or redness to appear. It’s basically a sunburn; based on this, an SPF rating is assigned.

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Why is SPF human testing a problem?

If sunscreens only contain approved ingredients that we know are safe, is it really a problem that they are tested on humans?

Unfortunately yes. Human testing involves exposing people to harmful UV rays, which we know can cause skin and eye damage, as well as being the leading cause of skin cancer. This alone is unethical and unjustifiable.

There are also other issues associated with testing sunscreen on humans. For example, using erythema to determine the effectiveness of sunscreen is very subjective and can differ from person to person, even for those with the same skin type. This makes the reliability of these test methods questionable.

In addition, the tests are only carried out on a small number of people (a minimum of ten people is required in Australia). This is great for exposing as few people as possible to harmful UV rays to determine a product’s SPF rating – but not so good when it comes to inclusivity.

Testing such a small number of people is not representative. It does not include all skin types and poses real challenges in achieving reproducible results in different labs testing the same product.

The tests themselves are also very expensive. This adds to the already high cost of buying sunscreens and potentially prevents manufacturers from developing new, better products.

These, and many other issues, underscore the urgency of developing non-human (in vitro) methods of testing sunscreen effectiveness.

Humanless SPF testing technology is under development

Although efforts have been made to develop non-humane testing methods, several challenges remain. These include the materials used to simulate human skin (also called substrates), the difficulties of applying sunscreen to these substrates, the reproducibility of results, and ensuring that results are the same as seen with testing. on the man.

However, scientists at RMIT University, with support from the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) and Cancer Council Victoria, are working on a solution to this problem.

So far, they have developed a prototype sensor that changes color when exposed to UV light. This sensor could be customized for non-human sunscreen testing, for example.

Reliable in vitro testing methods will mean that in the future, sunscreen manufacturers will be able to manufacture and test new and better sunscreens quickly, without being limited by the time and cost constraints of testing. on the man.

So the next time you shop for a bottle of sunscreen, look to buy the top rated SPF 50+ sunscreen – and know that work is underway to achieve that more ethically rated rating.The conversation

Sarah Loughran, Director Radiation Research and Advice (ARPANSA) and Adjunct Associate Professor (UOW), University of Wollongong and Sylvia Urban, Professor of Chemistry, School of Science (Applied Chemistry and Environmental Science), RMIT University.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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