Jan. 12, 2004 -- For years, rumors have circulated on the Internet that antiperspirant use causes breast cancer, despite a complete lack of scientific evidence to support the claim. Cancer experts say there is no cause for concern, but a group of researchers in the U.K. aren't so sure.
The investigators report finding preservatives commonly used in antiperspirants and other cosmetic products in breast tumors. Their earlier work also implicated the preservatives, known as parabens, as weak promoters of estrogen-dependent breast cells.
Although they are not saying that parabens cause breast cancer, lead researcher Philippa Darbre, PhD, and colleagues are hoping the findings will lead to larger studies.
"Our research certainly does not prove causality, but we believe that in a few of these tumors the level of this chemical was high enough to promote breast cancer cell growth," Darbre tells WebMD. "We don't know, however, if parabens can cause normal cells to become cancer cells."
Little Support for Controversial Idea
Darbre says she is convinced antiperspirants can cause breast cancer but has received little support from the scientific community to test the hypothesis. If she gets funding, the researcher says she hopes to study whether aluminum, which is the active ingredient in most antiperspirants, is also present in breast tumor tissues and whether these chemicals are present in healthy breast tissue.
"I have no doubt that if chemicals in underarm cosmetics are involved in breast cancer, some people will be more susceptible to this than others," she says. "These products may be perfectly safe for some but not for others."
In an editorial accompanying the study, published in the January issue of the Journal of Applied Toxicology, toxicologist Philip W. Harvey, PhD, also calls for more research into the safety of parabens and other chemicals in cosmetics that may promote the growth of estrogen-dependent tumors.
"Absence of evidence is not evidence of absence of a harmful effect," he tells WebMD in an interview. "These chemicals are being directly applied daily, by very large numbers of people, and the long-term health effects of exposure are essentially unknown."
'Risk Is Minuscule'
But American Cancer Society epidemiologist Michael Thun, MD, says even if the parabens do promote estrogen-dependent tumor growth, the risk from cosmetic use is "minuscule" compared with other known tumor promoters.
In his editorial, Harvey cited animal studies suggesting that paraben exposure is 500 to 10,000 times less potent as a tumor promoter as taking oral estrogen or being obese.
"The risk at an individual level is tiny, compared to other known risks," Thun tells WebMD.
Thun says people should not worry about using antiperspirants, but he says that the findings must be taken seriously by regulators who are responsible for assessing the safety of consumer products.
"If this substance is in multiple cosmetics and is being absorbed through the skin, it needs to be looked at more closely," he says.