Sunscreen

The main chemical used in sun lotions to filter out ultraviolet light may be TOXIC, particularly when exposed to sunshine.

Octyl methoxycinnamate (OMC), which is present in 90 per cent of sunscreen brands, was found to kill mouse cells even at low doses in a study by Norwegian scientists.

It is not certain that the effects on mice are repeated in human beings, although the findings reported in New Scientist magazine suggest that human cells could be damaged if a sunscreen containing OMC penetrates the outer layer of dead skin and comes into contact with living tissue.

Terje Christensen, a biophysicist from the Norwegian Radiation Protection Authority, near Oslo, said her research showed that sunscreens should be treated with caution, and used only when it was impractical to stay indoors or to shield the skin from the sun with clothes.

The chemical is used as a filter for the more harmful UVB light. In Dr Christensen's study, mouse tissue grown in culture was treated with a solution of OMC at five parts per million - a much lower concentration than in sunscreens. Half the cells treated with OMC died, compared with fewer than 10 per cent in a control experiment.

When researchers shone a lamp for two hours to simulate midday sunshine, more cells died. Dr Christensen suggested that the reaction between OMC and sunlight created an effect that was twice as toxic as the chemical alone.

The Sunday Times (London) Mark Henderson, Science Correspondent