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Monday’s medical myth: SPF50+ sunscreen almost doubles the protection of SPF30+

SPF50+ only increases protection by 1.3%. Flickr/the half blood prince

It’s likely Australia’s sunscreen regulations will change this summer, enabling manufacturers to label their products as SPF50+.

The sunscreen industry has championed the proposed change, led by Standards Australia, because the SPF50+ label will prompt many Australians to buy new product, thinking they’re getting significantly higher protection from the sun.

But what does SPF50+ actually mean? And will it provide better protection?

The Sun Protection Factor (SPF) indicates the amount of UVB radiation that can reach the skin (and cause sunburn) with sunscreen, compared with no sunscreen.

In other words, SPF ratings indicate the multiples of time you could spend unprotected in the sun without burning, assuming the UV rating was constant.

But no sunscreen offers full protection from the sun. And the increment in UVB filtering between SPF30+ and SPF50+ is small, increasing protection from 96.7% to 98%. That’s a 1.3% increase, not almost double, as many people may think when making a purchasing decision.

Whether it’s SPF30+ or 50+, sunscreen alone isn’t enough to protect you against skin cancer. Flickr/Liberalthug

Many sunscreens contain a combination “inorganic” (minerals, produced using chemical processes) and “organic” (chemical) ingredients.

Inorganic ingredients both absorb and reflect UV radiation, whereas organic ingredients only absorb. This means the energy from the UV radiation is used to convert the organic chemical into another form. But you wouldn’t feel any heat produced from such a change.

As our understanding of sunscreen’s role in protecting consumers from skin cancer evolves, sunscreen manufacturers are offering other protections. “Broad spectrum” sunscreens now protect against UVB and UVA radiation, which we now know contributes to the development of skin cancer.

Inorganic ingredients, such as titanium dioxide and zinc oxide, may offer a broad spectrum protection but they simply reflect the UV. They also tend to be gentler on the skin.

So what’s likely to happen if and when SPF50+ comes on to the market?

My concern is that consumers will think the increased SPF factor offers significantly better protection than the products they’re accustomed to. And if this leaves Australians using less sunscreen and neglecting other protection behaviours, we’re likely to see a future spike in skin cancers.

Australia has one of the highest rates of skin cancer in the world due to our climate and large fair-skinned population. More than 10,300 Australians are diagnosed with a melanoma each year and an estimated 434,000 people are treated for one or more non-melanoma skin cancers.

Despite the popular slip, slop, slap campaign from the 1980s, more than 1,830 Australians die from a skin cancer each year. Even though it’s largely preventable.

Skin cancers form when skin cells are damaged by UV radiation penetrating the skin. Tanning without burning can still cause damage – if you’ve been exposed to enough UV to cause tanning, sufficient damage has been done to cause cancer.

It doesn’t matter whether you use SPF30+ or SPF50+ sunscreen, the best way to protect yourself from skin cancer is with a combination of clothing (slip), sunscreen (slop), hat (slap), sunglasses (slide) and shade (seek), whenever the UV index reaches three or above.

Tips for applying sunscreen:

  • Make sure your sunscreen is at least SPF30+, water resistant and broad spectrum, which protects you from UVB and UVA;

  • Apply 20 minutes before you go outdoors and reapply every two hours;

  • Use at least one teaspoon of sunscreen for each limb, your face and the front and back of your body;

  • Check the use-by date;

  • Never rely on sunscreen – whether it’s SPF30+ or SPF50+ – as your only defence against the sun.

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