There may be reasons to worry—though hard proof remains elusive.
If you’ve seen the 1989 film Batman—the one with Michael Keaton and Jack Nicholson—you’ll recall that the Joker terrorizes Gotham City by slipping toxic chemicals into cosmetics: while no single item is lethal, combining deodorant with shampoo and lipstick could kill you.
It’s hard not to think of that movie while chatting with toxicologists who study the potential risk of deodorant and antiperspirant ingredients, especially parabens and aluminum. However, according to the American Cancer Society’s website, there is no “clear” or “direct” link between parabens or aluminum and cancer. The National Cancer Institute site says “more research is needed.”
The FDA, for its part, says “FDA believes that at the present time there is no reason for consumers to be concerned about the use of cosmetics containing parabens. However, the agency will continue to evaluate new data in this area. If FDA determines that a health hazard exists, the agency will advise the industry and the public.
But “absence of evidence is not evidence of absence,” says Dr. Philip Harvey, editor-in-chief of the Journal of Applied Toxicology.
Dr. Philippa Darbre, an oncologist at the University of Reading in the U.K., has published more than 30 research papers on those substances found in underarm deodorant and other personal care products. She says that many of these ingredients are concerning on their own. But the health risks of each may be greater—and more difficult to identify—when you consider the complex chemical cocktails that form when they combine.
For example, her research has detected parabens—a category of chemical that acts as a preservative in some underarm and personal care products—in women’s breast tissue, though how those parabens got there and what happens when they are in breast tissue is unknown.
In Darbre’s experiments, combining different parabens with human cells creates activity that may contribute to the development of cancer. But attempts to find these links in humans—as opposed to in petri dishes—have produced inconsistent results. One 2002 study found no correlation between underarm product use and breast cancer; a 2003 study did find ties. Darbre says both studies have flaws and leave many important questions unanswered.