Preventing skin cancer: Slip and slap are better than slop

Will "Slip Slop Slap," a southern hemisphere campaign to prevent skin cancer, have to be rethought?

The slogan, running especially in Australia and New Zealand, urges the public to slip on a shirt, slop on sunscreen and slap on a hat to protect themselves from ultraviolet (UV) rays that age skin and cause skin cancer.

But, according to a review of the evidence published online Thursday by the British health journal The Lancet, skin protection is a rather more complex business than this.
Wearing thick garments -- and avoiding direct exposure to the sun in the first place -- are smarter than wearing loose-weave clothing and applying sunscreen, it says.

Sun-protection strategies around the world were assessed by Swiss dermatologist Stephan Lautenschlager of Zurich's Triemli Hospital.

His team found that tightly woven, thick clothing made of denim, wool and polyester offers the best protection, while cotton, linen and acetate are far less effective.

Clothes that have shrunk after washing -- and thus are denser -- are also better than materials which are wet or have been stretched or bleached, according to Lautenschlager's team.

The review says that many people are confused or misinformed about how to use sunscreen, such as how much to apply (a liberal dose is recommended by far) and how frequently to reapply it.

There is not even a standardised method to measure the effectiveness of UV blocking, it says.

This is important, given "our global, outdoor society," it says.

"The sunscreen market -- crowded by numerous products -- shows various differences worldwide," it notes. "(...) Sunscreens should not be abused in an attempt to increase time in the sun to a maximum."