A peer-reviewed study published Sunday found that breast milk samples from mothers in Seattle contained hormone-disrupting chemicals at levels that prior research has linked to developmental harm in infants, adding to a growing body of evidence on widespread chemical contamination in the U.S. food and consumer product supply.
Researchers with the nonprofit Toxic Free Future tested 50 samples for a range of plasticizers and antimicrobials used across the economy. About 92% of the samples were contaminated with at least one of the compounds, the study found. The chemicals detected included bisphenol A (BPA), bisphenol S (BPS), melamine, cyanuric acid, and triclosan.
The study is among the first to detect melamine along with multiple other classes of endocrine-disrupting chemicals in breast milk, the authors said.
Ryan Babadi, a lead author of the study and senior scientist with Toxic Free Future, said the chemical mixture poses particular risks to infants.
“This pertains to the most vulnerable group when it comes to health effects — infants and children — who are undergoing rapid stages of development that are orchestrated by the endocrine system,” Babadi said.
The research found BPA in 74% of samples and BPS in 78%. Epidemiological studies have linked BPA to impaired neurodevelopment, asthma, and obesity, and BPS has been associated with lower weight in young children, according to the researchers. Triclosan appeared in 62% of samples, and melamine was detected in 92%.
Babadi said the results are “concerning for a number of reasons,” but emphasized that breastfeeding remains the healthiest choice for infants when possible, because it is the most nutritious and generally safest option. Many of the same chemicals are also found in infant formula, he noted.
The endocrine-disrupting compounds are added to everyday products across the economy for a range of purposes, the study said. Triclosan serves as an antimicrobial in personal care products. Melamine, BPA, and BPS are used as resins that prevent products from sticking to packaging, help give plastic its form, or provide UV protection.
The same milk samples that Babadi’s team analyzed had previously been found to contain PFAS “forever chemicals” and flame retardants, which are also endocrine disruptors.
The study’s authors acknowledged several limitations, including a small sample size and a participant pool that was broadly more educated and higher-income than the general population. Some of the compounds were found at levels below the World Health Organization’s tolerable daily intake, the study noted, but still at concentrations that previous research has shown may cause disease.
Babadi said individual consumers have limited options for avoiding the compounds because they are so widely used in consumer goods.
“People cannot shop their way out of this,” Babadi said.
The findings come as the Trump EPA pursues a multi-pronged effort to roll back chemical regulations. The agency has moved to undo limits on toxic chemicals and carcinogens in consumer goods and water and has sought to weaken the regulatory process. Congress is considering legislation to overhaul the nation’s toxic chemical laws.
Babadi said the study’s findings underscore the need for stronger protections.
“That would make the exposures we see in this paper worse, and it would worsen the health of not only children but adults, workers and communities,” Babadi said.