Endocrine-disrupting chemicals found in breast milk and infant urine up to age 6 months

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 presented at ENDO 2026, the Endocrine Society’s annual meeting in Chicago.

“Breast milk is the optimal nutritional source for any child and must be protected as it is a vehicle of environmental contaminants,” said Maria Elisabeth Street, M.D., Ph.D., associate professor and director of the Division of Pediatric Endocrinology at the University of Parma and University Hospital of Parma in Parma, Italy. “Infancy represents a critical window of exposure since effects are magnified at this age, with damage becoming evident after many years.”

Street and colleagues used data from 336 mother-infant pairs enrolled in the LIFE-MILCH project. Samples were collected 1 month, 3 months and 6 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 1 month after birth (51.2%) and at 6 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 1 month after birth (10.7%), at 6 months after birth (18.3%), and in infant urine samples at birth (22.4%) and at 6 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 at 1 month (51.2%; 42.3%) and 6 months postpartum (56.2%; 52.6%) in breast milk, and increased in urine samples over time.

Glufosinate was detected in breast milk 1 month after birth (27.4%) and 3 months after birth (31.9%), and in urine samples at birth (44.7%) and at 6 months of age (38.2%).

Phthalates, including dibutyl phthalate (DBP), were found in 90.2% of breast milk samples at 1 month postpartum and 86.5% at 6 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 nutritional habits and products used for personal and household care, Street said.

Studies found exposure to these chemicals was 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.

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Sadie Harley

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