A recent study has shown that moisturizers induced skin cancer in mice opening questions on their safety for humans. Four commonly used moisturizers Dermabase, Dermovan (a wholesale-only product discontinued in 2006), Eucerin Original Moisturizing Cream, and Vanicream were tested by researchers at Rutgers University, New Jersey, in the United States.

Study leader Allan H. Conney, PhD, Director of Susan Lehman Cullman Laboratory for Cancer Research and professor at the School of Pharmacy at Rutgers University in Piscataway, N.J said that sun related skin cancer was shown in the mice and frequent applications of each product resulted in more skin tumors as well as faster tumor growth.

"This was unexpected. We really did not expect to see the tumor-promoting activity of these creams," said Conney.

The four common skin creams were tested on gene-altered hairless mice exposed to heavy doses of cancer-causing UV light. The study leader, however, felt this could be as rodent skin is more sensitive than human skin while other experts said they had reservations about the relevance of the study's conclusions.

The study found that the rate of non-melanoma skin cancers increased between 24 and 95% when compared to mice not treated with creams.

Surgically curable, non-melanoma skin cancer is very common in humans, and only in very rare cases it can prove to be fatal. The findings published in the Journal of Investigative Dermatology, part of the Nature Publishing Group in Britain, reported that follow-up experiments with a made-to-order cream missing several suspect ingredients which included mineral oil and sodium lauryl sulfate saw the cancer rates dropping sharply. Further tests would be needed to test the effect of these creams on human skin as rodent skin which is usually fur covered is thinner and more permeable than human skin.

Brian Diffey, an emeritus professor at Newcastle University in Britain felt the dose the rodents received exceeds what most people would experience in a lifetime. The UV source used to pre-sensitize the mice is a very poor surrogate for sun exposure.

As moisturizers are classified as cosmetics, the stringent checks that drugs have to undergo by FDA ruling, do not apply to them and experts feel that this should change.

Dermatologist Keyvan Nouri, MD, director of dermatologic surgery at the University of Miami Miller School of Medicine and author of the best-selling book on Skin Cancer, said, "This study could definitely be a warning to alert these companies to consider testing moisturizing creams with some sort of assay. These creams need to be tested first before they come to market."

The four creams analyzed in the study were: Dermabase, manufactured by Paddock Laboratories in Minneapolis, Minnesota; Dermovan, made by Healthpoint Ltd. in Fort Worth, Texas; Eucerin Original Moisturizing Cream, made by Beiersdorf Inc. in Wilton, Connecticut; and Vanicream, made by Pharmaceutical Specialities, Inc. in Rochester, Minnesota.