Sun lotions are not all they claim to be
Sun lotions give 'one twentieth of the protection they claim'
Popular sun lotions offer as little as one twentieth of the protection from sunburn and skin cancer advertised on the labels, says a study.
Scientists have shown that manufacturers calculate sunscreen Sun Protection Factors using a formula that assumes sunbathers cover themselves with four times as much cream as they actually do.
SPFs are supposed to be a simple guide for users. A SPF of ten means someone can stay in the sun ten times longer than normal without burning.
But the study found that most people apply sunscreen so thinly they don't get the full protection.
In practice a sunscreen cream advertising a SPF of 16 actually offers a protection factor of two.
Lead researcher Professor Hans Christian Wulf, of the University of Copenhagen, said: 'The factor on the bottles is more a level you may get if you did what they are doing in the test situation, but people are not doing that.
'Our results show that people who use sunscreen are less protected than they believe they are.'
European manufacturers work out the SPF by assuming 2mg of lotion is applied to every square centimetre of skin.
But when Professor Wulf's team carried out research on beaches in Denmark, they found the average amount applied by sunbathers was 0.5mg per cm squared.
To test the effect of this much lower dose, they rubbed Garnier Ambre Solaire SPF four to four patches of skin on the backs of 20 volunteers in doses of 0.5, one, two and four mg per square cm.
After exposing them to a sunlamp, and seeing how long it took for their skin to start to burn, they worked out the real SPFs.
They also used UV filters to simulate the effects of stronger sun creams.
They found that an advertised SPF of four, eight and 16 in reality offered a protection factor of 1.4, 1.7 and 2 respectively when sunbathers applied the average amount used. The results were published in the British Journal of Dermatology.
A spokesman for L'Oreal, which makes Garnier Ambre Solaire, said: 'It is very difficult to draw a conclusion from this small study, however we clearly state on our sunscreens that they should be applied generously and frequently.'
In May researchers working for Which? identified sun blocks made by M&S, Malibu and Tesco as claiming an SPF of 15, but having actual rating of 7.1, 10.2 and 12, even when sufficient cream was used. All three have challenged the findings.
By David Derbyshire of the UK Dail Mail