Researchers at Rutgers University in the United States tested four common skin creams on gene-altered, hairless mice exposed to heavy doses of cancer-causing UV light.
The scientist who led the study, however, cautioned that rodent skin is more sensitive than human skin, while other experts said they had reservations about the relevance of the study's conclusions.
Rates of non-melanoma skin cancers increased between 24 and 95 percent compared to control mice not treated with creams, the researchersfound.
Non-melanoma skin cancer is very common in humans, and is curable surgically. In very rare cases, however, it can prove fatal. When the scientists, led by Allan Conney, repeated the experiments with a made-to-order cream missing several suspect ingredients - including mineral oil and sodium lauryl sulfate - the cancer rates dropped sharply.
Rodent skin differs from human skin
Conney said that further studies were needed to test the impact of topical creams on people, as rodent skin, usually covered by fur, is thinner and more permeable than human skin.
His findings were published in the Journal of Investigative Dermatology, which forms part of the Nature Publishing Group in Britain.
Experts familiar with the study doubted its significance for humans. "The UV source used to pre-sensitise the mice is a very poor surrogate for sun exposure," commented Brian Diffey, an emeritus professor at Newcastle University in Britain.
What's more, the dose the rodents received exceeds what most people would experience in a lifetime, he said.
Doubt about relevance of study
Gordon McVie, a senior consultant at the European Institute of Oncology, said: "This has no relevance to causation of human skin cancer and does not prove in any way whatsoever that moisturising creams are cancer-causing in humans."
The four creams analysed in the study were: Dermabase, manufactured by Paddock Laboratories in Minneapolis, Minnesota; Dermovan, made by Healthpoint Ltd. in Fort Worth, Texas; Eucerin Original Moisturising Cream, made by Beiersdorf Inc. in Wilton, Connecticut; and Vanicream, made by Pharmaceutical Specialities, Inc. in Rochester, Minnesota. – (Sapa-AFP)
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