“You wouldn’t swallow a spoonful of toxic cosmetic ingredients,” wrote Time.com in 2016. “But in some ways, smearing them under your arms in the form of deodorant or antiperspirant may be worse.”

Included in the list of Time’s toxic ingredients: parabens, aluminum, and fragrances.

Concerns about parabens

“Parabens—a family of chemicals that act as preservatives—and fragrances can disrupt hormones that are linked to breast cancer,” says Robin Dodson, a scientist at Silent Spring Institute. (The nonprofit group studies how chemicals in the environment affect women’s health.)

Although parabens are not commonly used in antiperspirants and deodorants anymore, they are still used in some shampoos, conditioners, lotions, makeup, and other products.

What about aluminum?

Aluminum—the active ingredient in antiperspirants—temporarily plugs sweat ducts to reduce sweating. Deodorants have no aluminum, which is fine if you’re worried about odor, not sweat. (Tip: Ordinary baking soda also neutralizes underarm odor.)

But the evidence on cancer is weak. In the two largest studies, on a total of roughly 2,000 women, those who reported using antiperspirants (or deodorants) up to once a day had no higher risk of breast cancer than those who said they never used them.

The bottom line

There’s no strong evidence that antiperspirants cause cancer (or Alzheimer’s).

Want to avoid potential hormone disruptors? Go fragrance-free.