If you've checked out the back of your antiperspirant lately, you might have noticed something different: new labels required by the Food and Drug Administration. They point out that antiperspirants are "drugs" containing "aluminum" ingredients — that's what stops the sweat.
The aluminum is also what concerns some people, including Dr. Kris McGrath.
"I personally feel there is a very strong correlation between the underarm hygiene habits and breast cancer," McGrath tells CBS News correspondent Sharyl Attkisson.
McGrath, an immunologist and instructor at Northwestern University, has been intrigued by a potential breast cancer link since medical school.
It got personal when his wife — a frequent shaver and antiperspirant user — got breast cancer.
"She was diagnosed with breast cancer in 1987," McGrath says. "She died in 1989."
People who don't believe in a link point to this 2002 study that finds no connection.
But it didn't take into account how often a woman shaved and used antiperspirant, which McGrath considered crucial. So he did his own study of breast cancer patients and found this: The more these women shaved and used antiperspirants, the sooner they got breast cancer.
Is he trying to say all cases of breast cancer could be linked to antiperspirants and shaving?
"Absolutely not," McGrath says. "Breast cancer has existed since Hippocrates. But when you plot the sales of antiperspirant deodorants with the incidence of breast cancer in the United States, they both have grown in almost a parallel fashion."
It's not conclusive proof, but enough, McGrath says, to call for large-scale studies.
Rumors of a link between antiperspirants, shaving and breast cancer have circulated for years, but had been written off as an urban myth by most people — including the FDA's Web site which calls it a "...false...scary stories..." CBS News tried to ask the FDA whether the case really is closed, but they wouldn't let Attkisson interview any of their experts.
Instead, they seemed to shift from the "myth" status, telling CBS News: "FDA is aware of concerns that antiperspirant use (in conjunction with underarm shaving) may be associated with increased risk of developing breast cancer. FDA continues to search scientific literature for studies examining this possible adverse drug effect. Unfortunately, there are many publications that discuss the issue, but very few studies in which data has been collected and analyzed. Overall, the studies (containing data) are inconclusive in determining whether antiperspirants, in any way, contribute to the development of breast cancer. FDA hopes that definitive studies exploring breast cancer incidence and antiperspirant use will be conducted in the near future."
The billion-dollar antiperspirant industry says the products are undeniably safe.
"Has this issue been definitively laid to rest?" Attkisson asks John Bailey, a director of cosmetic chemistry as the cosmetic toiletry and fragrance association.
"I think the products are safe and I think that the best science is being applied to making that determination that they're safe," Bailey says.
"But you're not saying yes or no," Attkisson says.
"It's not a yes or no answer," Bailey replies.
The National Cancer Institute and American Cancer Society agree a link can't be conclusively ruled out. But they say there's no reason to throw out your antiperspirant in fear. Read the Cancer Institute's fact sheet.
McGrath advises his patients to consider the uncertainties. At least one of them thinks the government ought to go public and admit the breast cancer antiperspirant myth might not be a myth after all.
"I think the government should take an honest stand and say if they're not sure, so that women have the right to know and that they can make their own choice," says Michelle Bibergal.
On Tuesday's Evening News, Sharyl Attkisson will explain the difference between antiperspirants and deodorants and report on what alternatives are out there if you have health concerns.