Hormone-disrupting chemicals found in breast milk and infants' urine

Endocrine-disrupting chemicals (EDCs) that interfere with hormones were found in breast milk and in the urine of children from birth up to 6 months, according to a study being presented Saturday at ENDO 2026, the Endocrine Society's annual meeting in Chicago, Ill.

Breast milk is the optimal nutritional source for any child and must be protected as it is a vehicle of environmental contaminants. Infancy represents a critical window of exposure since effects are magnified at this age with damage becoming evident after many years."

Maria Elisabeth Street, M.D., Ph.D., associate professor and Director of the Division of Pediatric Endocrinology, University of Parma and University Hospital of Parma, Parma, Italy

Street and colleagues used data from 336 mother-infant pairs enrolled in the LIFE-MILCH project. Samples were collected one month, three months, and six months after birth.

The researchers measured exposure to more than 50 different chemicals, including bisphenols (BPA), polycyclic aromatic hydrocarbons, phthalates and metabolites, parabens, polar pesticides and pyrethroids.

BPA was commonly found in breast milk one month after birth (51.2%) and at six months postpartum (49.8%). Nearly a third of the infants had BPA in their urine samples following birth. The number increased to 67.6% when the infants were 6 months old.

Bisphenol S (BPS) was found in breast milk one month after birth (10.7%), at six months after birth (18.3%), and in infant urine samples at birth (22.4%) and at six months after birth (41.2%).

Most polycyclic aromatic hydrocarbons were rarely detected in breast milk, but several were consistently found in urine (up to 27.7%).

Methylparaben (MePB) and ethylparaben (EtPB) were most commonly found one month (51.2%; 42.3%) and six months postpartum (56.2%; 52.6%) in breast milk, and increased in urine samples over time.

Glufosinate was detected in breast milk one month after birth (27.4%) and three months (31.9%) after birth, and in urine samples at birth (44.7%) and at six months of age (38.2%).

Phthalates, including dibutyl phthalate (DBP), were found in 90.2% of breast milk samples at one month postpartum and 86.5% at six months postpartum. Levels in urine samples increased from 30.3% at birth to 79.4% at 6 months of age.

Most EDCs found in breast milk and urine samples are associated with nutrition habits and products used for personal and household care, Street said.

Studies found exposure to these chemicals were linked to neurodevelopmental issues, hormonal activation at birth, and androgenization, or the development of male reproductive characteristics. EDC exposure also can alter growth, weight and obesity, Street said.

The study findings have led to a prevention campaign with results currently under evaluation, and several stakeholders have signed agreements to monitor and reduce these chemicals in their products in Italy, Street said. The researchers urge public health officials to reduce exposure to EDCs and create preventive strategies to protect breast milk in a changing world.