The sunscreen scandal shocking Australia - the world's skin cancer hotspot

Australians have a complicated relationship with the sun: they love it, but they also fear it.

Effective public health messaging – which has drilled "Slip, Slop, Slap" into their heads – competes with a beauty culture which often idolises bronzed skin.

The country has the highest incidence of skin cancers in the world and it is estimated that two out of three Australians will have at least one cut out in their lifetime.

So when Choice Australia released its damning report in June, it immediately made waves. The group had tested 20 sunscreens in an independent accredited Australian lab, finding 16 did not meet the SPF, or skin protection factor, rating listed on the packet.

Ultra Violette's Lean Screen SPF 50+ Mattifying Zinc Skinscreen, a facial product that Rach says she used exclusively, was the "most significant failure" identified. It returned a result of SPF 4, something that shocked Choice so much it commissioned a second test that produced a similar reading.

Other products that did not meet their SPF claims included those from Neutrogena, Banana Boat, Bondi Sands and the Cancer Council - but they all rejected Choice's findings and said their own independent testing showed their sunscreens worked as advertised.

While there are clear guidelines as to what you are looking for, Dr Wong says there is still a lot of variability. That is down to skin texture or tone, or even the colour of the walls, and "different labs get different results".

But she says results are also quite easy to fake, pointing to a 2019 probe by US authorities into a sunscreen testing laboratory which resulted in the owner being jailed for fraud.

Many sunscreen brands from all over the world use the same manufacturers and testing labs - and so this issue is unlikely to be isolated to Australia, she adds.

"Until someone goes out and tests a whole bunch of sunscreens in other countries, we just don't know the extent of it."

She says the scandal is a reminder that regulations are only as good as they are enforced.

But while it has touched a nerve for many people who are at high risk for skin cancer simply by virtue of being Australian, Dr Wong said she felt the panic triggered by the investigation was blown out of proportion.

She points to the world's largest clinical trial of sunscreen, done in the 90s, which found that the daily use of an SPF 16 sunscreen dramatically dropped skin cancer rates.

"95% of the sunscreens tested [by Choice] have high enough SPF to more than halve the incidence of skin cancer," Dr Wong said.

"Some of the SPF testing, I feel, has become a bit more of a marketing exercise than a real reflection of efficacy."

The most important thing you can do when choosing a sunscreen, she says, is actually wear enough of it – a full teaspoon at least for each part of your body, face included.

And ideally you should apply it about every two hours, especially if you have been sweating a lot or swimming.

Experts also advise that you combine the sunscreen with other safety methods, such as wearing protective clothing and seeking out shade.