The Link Between Breast Cancer, Pregnancy and a Common Food Additive

Propylparaben: It is a common preservative in U.S. food, drugs and personal care products. And now scientists have  linked it to an increased risk for breast cancer in women exposed to this chemical at even low doses during pregnancy.  Why? Because this endocrine-disrupting chemical additive (EDC) can alter pregnancy-related changes in the breast in ways that may lessen the protection against breast cancer that pregnancy hormones normally convey*.

*Endocrine disrupting chemicals, as scientists have already confirmed, can affect organs sensitive to hormones, including the mammary gland in the breast that produces milk.  Hormones produced during pregnancy not only allow breast tissue to produce milk for the infant, but also are partly responsible for a reduced risk of breast cancer in women who give birth at a younger age.

Study overview

Scientists tested whether propylparaben exposure during the vulnerable period of pregnancy and breastfeeding adversely alters the reorganization of the mammary gland. They examined the mothers’ mammary glands five weeks after they exposed the female mice to environmentally doses of propylparaben during pregnancy and breastfeeding.


The mammary gland is a hormone sensitive organ that is susceptible to endocrine disrupting chemicals (EDCs) during the vulnerable periods of parous reorganization (i.e. pregnancy, lactation, and involution). Pregnancy is believed to have long-term protective effects against breast cancer development, however, it is unknown if EDCs can alter this effect. We examined the long-term effects of propylparaben, a common preservative used in personal care products and foods, with estrogenic properties, on the parous mouse mammary gland.

Results overview

Compared with pregnant mice that had not received propylparaben, the exposed mice had mammary gland changes not typical of pregnancy, the researchers report. These mice had increased rates of cell proliferation, which is a possible risk factor for breast cancer. They also had less-dense epithelial structures, fewer immune cell types and thinner periductal collagen, the connective tissue in the mammary gland.

“Because pregnant women are exposed to propylparaben in many personal care products and foods, it is possible that they are at risk…pregnant and breastfeeding women should try to avoid using products containing propylparaben and other parabens.”

-Joshua Mogus, researcher, coauthor of study, and Ph.D. candidate

Journal Reference: Mogus, J.P. et al.  Exposure to propylparaben during pregnancy and lactation induces long-term alterations to the mammary gland in mice, Endocrinology, bqab041, Published:16 March 2021. Summary.