Pesticide chemicals may increase breast cancer risk, study finds

A new study published in Environmental Health Perspectives by the Silent Spring Institute suggests that chemicals used in pesticides may increase the risk of breast cancer. Researchers analyzed over a dozen US government databases to identify primary sources of exposure to chemicals linked to breast cancer.

The findings highlight a regulatory gap regarding pesticide formulations. While safety assessments often focus solely on the ‘active ingredient,’ the study notes that individuals are exposed to the entire formulation. Of the 485 chemicals identified in these formulations, only about one-third (145) are registered as ‘active ingredients’ by the US Environmental Protection Agency (EPA).

Dr. Jennifer Kay, the lead author, and medical experts such as Professor Uğur Coşkun have noted that many of these substances can disrupt hormones like estrogen or progesterone, which play roles in breast cancer development. This research follows a 2024 study that identified over 900 chemicals capable of causing breast tumors or hormonal disruption in animals.