A study by British scientists suggests sunscreen lotions may not protect against skin cancer.
BBC News Online examines the findings and what they mean for sunbathers.
What did the scientists find?
Professor Roy Sanders and colleagues at the research charity Raft carried out tests on three leading sunscreen lotions.
They found that they protected the skin from burning.
However, they also found that they failed to stop the sun's damaging rays from penetrating the skin.
Why are these findings significant?
The discovery that sunscreen lotions fail to stop the sun's UVA rays from penetrating the skin raises serious questions about whether they can protect against skin cancer.
When these rays penetrate the skin, they can trigger the release of free radicals.
These agents can damage DNA, which can cause cancer.
While the scientists looked at just three brands, the findings raise questions about how effective other brands are.
These were all high factor popular creams.
The scientists say further tests are needed to found out what, if any, other brands protect against skin cancer.
Are sunscreen lotions supposed to protect against skin cancer?
According to manufacturers, their sunscreen lotions are supposed to protect against skin cancer.
Companies spend millions of pounds testing and marketing their products. Britons spend an estimated £156m on lotions largely because they believe they offer protection.
Manufacturers use a combination of chemical ingredients in their lotions.
They work by either absorbing the sun's rays or reflecting them away from the body.
Either way, they are supposed to stop rays from burning or penetrating the skin.
What are manufactures saying about these latest findings?
High street chemist Boots, which manufactures its own range of sunscreen lotions, has insisted its products are effective.
However, it agrees that people need to be sensible and should not depend on sunscreen lotions to protect them against the sun's damaging effects.
What does it all mean for sunbathers?
The findings provide more evidence of the dangers of exposing skin to the sun.
They also suggest that sun worshipers should not rely on sunscreen lotions to protect themselves from the sun's damaging rays.
Experts say they reaffirm the need to cover up when outside, by wearing hats and long-sleeved shirts, staying out of the sun when it is strongest around midday and stay in the shade.
Is there a real risk?
Yes. According to Cancer Research UK, there are almost 65,000 new cases of skin cancer or malignant melanoma in the UK each year.
The number of cases has more than doubled since the early 1980s
It now accounts for 2% of all newly diagnosed cancers.
Among people under 35, it is the third most common cancer in women and the fifth most common in men.
In the last five years, there have been 8,100 British deaths from malignant melanoma.
More Britons now die from skin cancer than in Australia.
It has the highest incidence of skin cancer in the world.
However, there is greater awareness of the disease and survival rates are better because it is spotted and treated earlier.