Sun-lovers Sloppy At Safety

Sun-seekers typically apply only enough sunscreen to obtain one-third of the protection stated on the product, experts say.

This mismatch may be one contributing factor to why sunscreens have been reported to be a risk factor in melanoma, the authors said in a letter to the British Medical Journal (22 June).

The authors, a New Zealand GP and a British medical physics professor, suggested a simple dose guide using the ‘rule of nines’, which divides the body into 11 areas, each of 9%.

Sunscreen could be applied to each area at a dose of 2mg per square centimetre – the equivalent of about two strips of sunscreen measured from the crease of the palm to the fingertips of the index and middle fingers.

However, the authors said people were unlikely to use such a large amount of cream.

Instead, they proposed applying one full finger of sunscreen, which would give about half the protection stated, then reapplying the same amount within half an hour of the initial application “in order to achieve optimal protection”.

Terry Slevin, director of education and research with the Cancer Foundation of WA, said people usually applied sunscreen quickly, and there was clear evidence from Australia and the UK that they generally did not apply enough to achieve the stated levels of protection.

“It is one of the reasons we always suggest that sunscreen should be considered a last line of defence when it comes to sun protection,” he said.

Australian Doctor, 28 June