The major component of most suncreams and lotions is oxybenzone, a chemical that acts as a broad-range UVA filter and partially filters UVB. Now Professor John Wood, from the biomedical sciences department at Bradford, and his wife and fellow researcher, Professor Karin Schallreuter, have discovered that when worn on skin in the sun, oxybenzone is broken down into different chemicals, some of which destroy or inhibit the skin's natural defence system against sunlight.
Sunlight is dangerous to skin because it releases free radicals - unstable groups of atoms with spare electrons which harm skin cells and are thought to be partially responsible for ageing. In the presence of UVB, large amounts of an enzyme called thioredoxin reductase migrate into the nucleus of skin cells to protect their DNA from these free radicals. But the break- down of oxybenzone makes thioredoxin reductase "commit suicide", leaving skin cells increasingly vulnerable to sunlight.
The researchers point out that it is too early to say whether this reaction may have a long- term effect on the skin, or whether the protection offered by suncream itself, in absorbing UV rays, cancels out any potential for damage, and that further research is needed before anyone panics. "Our results on the direct fate of oxybenzone in the human epidermis of different skin types strongly suggest that the use of this widespread UVA filter warrants careful reassessment," advises Professor Schallreuter.
Previous research has only looked at the effect of suncream on skin cultured in the laboratory - not on a live human being in the sun. The Bradford team was able to carry out research on a human volunteer, using laser Ramen spectroscopy, a relatively new technology. Shone directly on to the skin, the laser can give the chemical signature for every substance on the skin without harming the volunteer. "It's a wonderful step forward," says Professor Wood. "The sensitivity of this technique has just got to stage where you can look [at the skin's surface]."
Leading suncream manufacturers have expressed concern at the Bradford findings and a willingness to collaborate in further research. However, they all declined to speak to the Independent.