Exposure to Common Preservative During Pregnancy May Increase Breast Cancer Risk

Low doses of propylparaben–a chemical preservative found in food, drugs, and cosmetics–can alter pregnancy-related changes in the breast in ways that may lessen the protection against breast cancer normally conveyed by pregnancy hormones, according to research conducted at the University of Massachusetts Amherst. The findings suggest that propylparaben is an endocrine-disrupting chemical that interferes with the actions of hormones and can potentially affect the mammary glands, according to the study authors.

“We found that propylparaben disrupts the mammary gland of mice at exposure levels that have previously been considered safe based on results from industry-sponsored studies. We also saw effects of propylparaben after doses many times lower, which are more reflective of human intake,” said the study's senior author, Laura Vandenberg, PhD, in a press release. “Although our study did not evaluate breast cancer risk, these changes in the mammary tissue are involved in mitigating cancer risk in women.”

The researchers examined the mammary glands of mice 5 weeks after exposing them to environmental doses of propylparaben during pregnancy and breastfeeding. The exposed mice had mammary gland changes not typical of pregnancy compared to pregnant mice who had not received propylparaben. They had increased rates of cell proliferation, which is a possible risk factor for breast cancer, as well as less dense epithelial structures, fewer immune cell types, and thinner periductal collagen, which is the connective tissue in the mammary gland.

“This chemical is so widely used, it may be impossible to avoid entirely,” said co-lead author Joshua Mogus in the press release. “It is critical that relevant public health agencies address endocrine-disrupting chemicals as a matter of policy.”

Mogus suggests future studies should focus on analyzing whether pregnant women exposed to propylparaben are actually more susceptible to breast cancer. The hormones produced during pregnancy are partly responsible for reducing the risk of breast cancer in women who give birth at a younger age, according to the study.

REFERENCE

Exposure to common chemical during pregnancy may reduce protection against breast cancer [news release]. EurekAlert; March 16, 2021. Accessed March 18, 2021. https://www.eurekalert.org/pub_releases/2021-03/uoma-etc031621.php