What is the problem?

Twenty years ago 814 new cases of malignant melanoma, the most dangerous type of skin cancer, were registered. That's an age-standardised rate of 21.2 per 100,000 of the population. In 2004, the year for which the most recent figures are available, there were 1896 new registrations - a rate of 33.2 per 100,000.

Much of the increase can be explained by the time lag necessary for melanoma to develop. Rates for those 45 years and older have climbed dramatically as baby-boomers pay for summers spent in search of the perfect tan. But in 2004 there were 82 new registrations of melanoma in 30- to 34-year-olds, a rate of 28.0 per 100,000. It was the most common cancer in 15- to 24-year-old women. These are people who grew up after the dangers of ultraviolet (UV) radiation from the sun were well known.

Given the long-running public campaign to warn people of the dangers of sun exposure, what's the problem?

Sunscreen alone is not enough

The Cancer Society of New Zealand's Dr Judith Galtry says we rely too much on sunscreen alone. Protecting yourself when UV radiation levels are at their peak - in the daylight-saving months, especially between 11am and 4pm - involves more than one strategy.

"Sunscreen shouldn't be the only (or even the first) line of defence," she says. "It's very important but it's complementary to limiting your time in the sun and using hats and cover-up clothing."

Studies have shown a reduction of two types of skin cancer in "careful and regular" sunscreen users. But many people aren't using their sunscreen to reduce their UV exposure. Instead, they use sunscreen to stay out longer in the sun without burning. Some UV rays always get through, adding to the damage your skin has already suffered.

Irresponsible claims?

We think these label claims are irresponsible because they encourage people to think they can stay out in the sun for long periods.

"SPF 70"

The Australia/New Zealand Standard allows SPF claims of no more than 30+, and the proposed US Federal Drug Administration regulations limit claims to SPF 50+ as it says this is the highest that can currently be determined by accurate and reproducible testing. Increases in SPF values above 50 provide little extra protection.

"Sunblock"

The European Commission and the proposed FDA rule ban the use of terms such as "sun block" to imply a sunscreen gives total protection. Even high SPF products let some UV radiation through.

"Daylong" and "10-hour protection"

This goes against the advice of Australasian, European and US authorities to reapply sunscreen regularly - every two hours. The European Commission says there should be no claims such as "all day prevention". Sunscreen protection diminishes over time and people simply don't apply enough.

Daylong is sold as a "Kids' Formula". In our view this is doubly irresponsible.