A CHEMICAL found in some sunscreens may increase the risk of cancer, an Oxford academic has claimed.

Dr John Knowland, a dermatologist at Pembroke College, said his research had so far been conducted in a test tube and had produced evidence only of changes that precede cancer.

But he told the American Association for the Advancement of Science's annual meeting, in Philadelphia, that he would not use a sunscreen containing Padimate-O.

In sunlight, Padimate-O may generate free radicals, known to attack the body's DNA, causing mutations that can lead to cancer.

Sunscreen chemicals work by absorbing UV energy before it gets to the skin but sunscreens cannot destroy that energy and Dr Knowland is worried that the energy may fuel undesirable reactions in the skin.

He said: "If DNA cells were to be damaged by that energy the consequences could be serious. We do not know if it happens in humans using sunscreens that contain Padimate-O."

In 1935, there was a one in 1,500 chance of developing a melanoma but within two years it will reach one in 75 - a 20-fold increase.

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