It has to do with certain underarm products that contain preservatives called parabens. These chemicals can act like the hormone estrogen in the body. Estrogen is known to fuel certain breast cancers. Many breast cancers develop in the part of the breast closest to the armpit, where antiperspirants and other underarm products are used.
Now a new study shows that yes, there is evidence of parabens in 99% of breast tissue samples taken from women with breast cancer, but many of these women did not use any underarm products. Most major brands of deodorants and antiperspirants no longer contain parabens.
So where are all the parabens coming from? Parabens such as methylparaben, ethylparaben, propylparaben, butylparaben, isopropylparaben, and isobutylparaben are also found in makeup, moisturizers, and hair care and shaving products.
The new study included 40 women with breast cancer who chose to have a mastectomy. Researchers looked at four samples of breast tissue from each woman. The tissue samples came from several locations within the breast, including the armpit region.
Fully 99% of the tissue samples had evidence of at least one paraben, and 60% showed evidence of five. Paraben levels did not seem to play a role in the cancer’s location or whether or not the cancer was fueled by estrogen.