Scientists at the Memorial Sloan Kettering Cancer Center in New York and the US Government’s Brookhaven laboratory found that sunscreens protected against sunburn and cancers like carcinoma, but not against the serious skin cancer melanoma, which has increased twentyfold in Europe and the USA since 1935.

A separate piece of research from Oxford University scientist John Knowland showed that PABA, a chemical compound found in some sunscreens, seemed to damage DNA, thus increasing the risk of skin cancer. He recommended using non-PABA products.

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An active ingredient in sunscreens, 2-phenylbenzimidazole-5 (PBSA), which is used to absorb ultraviolet B (UVB), was found to damage DNA when exposed to sunlight in a test tube. The researchers from Queen’s University in Belfast (N. Ireland) fear that if it caused similar changes to skin cells, this could lead to skin cancer.

Although there was no definite proof yet that this was occurring, the researchers recommended that an alternative UVB absorber is found.

Original research: Chemical Research in Toxicology. Publ.: The American Chemical Society (Tel.: 00 1 2028 724445, website: www.acs.org)

Margaret Schlumpf and colleagues from Zurich University’s Institute of Pharmacology and Toxicology were alarmed by some of the chemicals used in sun screens, and by the way these chemicals are accumulating in our bodies and in the environment. They warned that they have the potential to cause cancer and to interfere with the human reproductive system.

The six UVB screening chemicals they tested - benzophenone 3, honmosalate, 4-methyl-benzilidene camphor (4-MBC), octyl-methoxycinnamate and octyl-dimethyl-PABA all behaved like oestrogen in laboratory tests, i.e. they make cancer cells grow rapidly. Three of the five also caused developmental effects in animals. Concentrations of 4-MBC allowed in sunscreens, for instance, mixed with olive oil and applied to the skin of rats doubled the rate of uterine growth well before puberty.

The scientists accepted that there was no firm proof yet that the levels in sun screens will damage health but are concerned that frequent use will increase the danger as the chemicals accumulate. Margaret intended to test another 25 common sunscreen chemicals for similar hormonal activity, as well as to monitor the above rats’ offspring. She suggested that sun screens like zinc oxide are safer.