Sunscreen labels can be misleading

By SIMON COLLINS

Sunscreen labels can give a misleading impression of the protection offered, researchers say.

Mairangi Bay GP Steve Taylor and British medical professor Brian Diffey write in this month's British Medical Journal that sunscreen makers should tell people they need "two fingers' worth" of sunscreen on every exposed area to get the protection the manufacturers claim.

And that's not just two dobs of sunscreen on the end of the fingers, but enough to be squeezed out in a line down both fingers for your face and each arm and leg.

The two researchers say it is unlikely people will ever smear their bodies with so much sunscreen.

So they propose a more realistic "one-finger" rule - "with the corollary that the resulting protection would only be about 50 per cent of that stated on the product".

"The average person is getting a third to a quarter of the sun protection factor that they think they are getting," Dr Taylor said. "It's not only misleading, it's probably dangerous."

Every summer his Sunset Rd Family Doctors clinic is inundated with people suffering the long-term effects of sunburned ears, necks and other parts of the body which they have failed to protect adequately with sunscreen.

"Men are the worst. Ladies are fine, they are always putting creams on their faces, but trying to get blokes to put sunscreen on is a nightmare."

The Auckland region has the world's highest rate of melanoma.

The sun protection factor (SPF) on labels compares the amount of ultraviolet energy required to burn your skin when it is covered by a sunscreen to the amount required to burn you without protection.

That means a sunscreen with an SPF of 10 will allow you to take 10 times as much sun as you could normally before you start to burn.

Most people burn after about half an hour in the summer sun.

However, Dr Taylor says that does not mean wearing an SPF 10 sunscreen will allow you to stay in the sun for five hours.

For one thing, the sunscreen is washed off by sweat and washes off when you swim, and the manufacturers recommend that you should put it on again every two hours.

Dr Taylor said this meant ultra-high SPF factors such as the common "SPF 30+" were meaningless because there was no way that people could need that much protection against burning in two hours. For most people, SPF 15 would be plenty, as long as it was kept up through the day.

Moreover, most people do not use enough cream in the first place.

The sun protection factor is assessed on the basis of an internationally agreed thickness of 2 milligrams per square centimetre of skin.

Dr Taylor and Professor Diffey have calculated that this requires two fingerlengths of sunscreen on each of the 11 areas that might be exposed: (1) the head, face and neck; (2) left arm; (3) right arm; (4) upper back; (5) lower back; (6) upper front torso; (7) lower front torso; (8) left upper leg/thigh; (9) right upper leg/thigh; (10) left lower leg/foot; (11) right lower leg/foot.

But for an adult, this would mean putting on more than a quarter of a standard 120ml tube every two hours. They believe this is too much to ask.

They therefore propose that people should put one fingerlength of sunscreen on each of the 11 body areas initially, followed by a top-up after half an hour.

"The situation is analogous to painting a wall with a textured surface when two coats of paint are almost always required for satisfactory coverage," they write.

"In the same way two 'coats of sunscreen' may be required for adequate protection."

Sunscreen manufacturers backed up Dr Taylor's comments.

Deborah Higgins of Beiersdorf (Nivea) said people should put sunscreen on 20 to 30 minutes before going out in the sun, and put it on again every two hours.

"We are very aware that there is still a lot of education to be done."

"A few years ago you could apply a factor of 65, but no one should be in the sun 65 times longer than the burn time because the daylight doesn't even last that long. You can't claim over 30 because it was just getting ridiculous."

Warren Smith of Douglas Pharmaceuticals, which distributes the Ego range, said manufacturers were trying to overcome people's resistance to putting on loads of white cream by developing transparent sprays.

"We've got a spray coming out this summer. The creams are slowly disappearing."

Has the sun protection factor had its day? (bmj.com)

nzherald.co.nz/health