Can propylparaben in cosmetics promote breast cancer?

What's actually in it

Propylparaben is a preservative used in lotions, deodorants, shampoos, and makeup to prevent bacterial growth. It absorbs through your skin and enters your bloodstream. Parabens have been found in breast tissue samples from cancer patients, meaning they accumulate right where breast tumors develop.

Propylparaben is an estrogen mimic. It binds to estrogen receptors in your cells and turns on the same genes that estrogen does. Breast cancers driven by estrogen are the most common type.

What the research says

A 2026 study in Ecotoxicol Environ Saf tested propylparaben's effects on estrogen-receptor-positive breast cancer cells. They used both computer modeling and lab experiments to identify exactly which cancer pathways it activates.

Propylparaben turned on multiple cancer-promoting genes in breast cells. It boosted cell growth, helped cells avoid programmed death, and activated signaling pathways that drive tumor progression.

The effects happened at concentrations that match real human exposure levels. You don't need extreme doses. The amounts that build up from daily cosmetic use were enough to switch on these cancer pathways in the lab.

The study also found that propylparaben worked through some pathways that are different from those targeted by standard breast cancer drugs. That means it could potentially fuel cancer growth even in patients receiving treatment.