New Study Finds Hormone-Disrupting Chemicals in Breast Milk and Babies' Urine

Breast milk remains the best source of nutrition for babies, but new research suggests it may also carry traces of hormone-disrupting chemicals that infants continue to accumulate during their first six months of life.

A new study presented at ENDO 2026, the Endocrine Society's annual meeting, found that several endocrine-disrupting chemicals (EDCs) were commonly detected in both breast milk and the urine of infants from birth to six months of age.

The study analyzed 336 mother-infant pairs participating in the LIFE-MILCH project. Researchers collected breast milk and urine samples one, three, and six months after birth and tested them for more than 50 environmental chemicals, including bisphenols, phthalates, parabens, pesticides, and polycyclic aromatic hydrocarbons.

One of the most frequently detected chemicals was bisphenol A (BPA), which appeared in about half of breast milk samples at both one and six months after delivery. BPA was also found in nearly one-third of infant urine samples shortly after birth, rising to almost 68% by six months. Similar increases were observed for bisphenol S (BPS) and several phthalates, chemicals commonly used in plastics and consumer products.

Researchers also detected preservatives known as parabens and the herbicide glufosinate in a substantial number of breast milk and infant urine samples. While most polycyclic aromatic hydrocarbons were rarely found in breast milk, several were consistently detected in infants' urine.

According to the researchers, many of these chemicals are linked to everyday exposures through food packaging, personal care products, household items, and dietary habits. Previous studies have associated endocrine-disrupting chemicals with altered growth, obesity, hormone disruption, and neurodevelopmental problems, although this study did not examine health outcomes directly.

The researchers emphasize that the findings should not discourage breastfeeding. Instead, they say the results underscore the importance of reducing environmental contamination and limiting exposure to hormone-disrupting chemicals.

REFERENCE: EDCs found in breast milk and infant urine up to age 6 months; https://www.endocrine.org/news-and-advocacy/news-room/2026/street-press-release-endo-2026