Q: Are antiperspirants with aluminum harmful? Can they really cause breast cancer?

In short: no, this is an old myth that gave marketers a chance to introduce a new type of product – aluminum-free sweat protection.

Antiperspirants most commonly contain two types of active ingredients: aluminum chlorohydrate and aluminum zirconium tetrachlorohydrex. They work by reacting with the electrolytes in our sweat, resulting in the formation of gel-like “plugs” in the sweat gland ducts.

So why do people think sweat protection products can cause breast cancer?

As usual, it stems from studies on cell cultures (which were later not confirmed in clinical trials with live humans). For example, in one such in vitro study, scientists found that aluminum could affect estrogen receptors, suggesting a possible link to breast cancer. However, it’s important to remember that in cell studies, the substance is essentially “poured” directly onto the cells to see what happens. For aluminum to similarly affect human cells, it would need to penetrate the skin in high concentrations (and studies show that only a very small amount penetrates – just 0.012%). In a study on humans (involving 813 women with breast cancer and 793 without), no link was found between breast cancer and the use of deodorants or antiperspirants. As Dr. Rob-Nicholson, editor of Harvard Health Publishing, aptly noted: any “side effects” from estrogen-like components we get from food or cosmetics are incomparable to the effects of our own ovaries.