Common chemicals in plastics, personal care products, and food packaging may drive the onset, growth, and spread of breast cancer—the second-leading cause of cancer deaths in women, new research suggests.

Breast cancer is one of the most common and deadly cancers worldwide, causing more than 42,000 deaths in the U.S, with particularly high rates among Black women. Only 5 to 10 percent are inherited, meaning most arise from environmental and lifestyle factors.

The findings, published this month [September 2025] in Ecotoxicology and Environmental Safety, suggest phthalates hijack the body’s hormone systems, activate cancer-promoting genes, and make tumors easier to form. and harder to treat. The study raises new questions about the safety of chemicals that millions of Americans encounter every day in air, food, and water.

“Phthalates are pervasive environmental toxicants that influence the initiation, progression and metastasis of breast cancer,” said the scientists, led by Dr. Michal Toborek at the University of Miami’s Leonard M. Miller School of Medicine.