Breast milk from dozens of Seattle-area moms carried a mix of hormone-disrupting chemicals, according to a new local study that is raising tough questions about what babies are being exposed to in their first months of life. Researchers found multiple endocrine-disrupting compounds, including several bisphenols and the antibacterial agent triclosan, in most of the 50 breast milk samples they tested. The scientists are quick to stress that breastfeeding is still considered the healthiest option for most infants, while urging stronger controls on the chemicals that are getting into parents in the first place.
What the study measured and what it found
The paper, published in the Journal of Exposure Science & Environmental Epidemiology, analyzed breast milk collected in Seattle in 2019 from 50 participants and screened it for dozens of endocrine-disrupting chemicals. According to the Journal of Exposure Science & Environmental Epidemiology, researchers detected melamine, cyanuric acid, BPA, BPS and triclosan in roughly 62–92% of samples and estimated how much of each compound infants might be ingesting daily via milk. The authors say the findings make breast milk an important exposure pathway to track, even as they note limitations from the relatively small sample size and call for more follow-up work on potential health effects.
Local experts: 'The problem is not breast milk'
Ryan Babadi, science director at the nonprofit Toxic Free Future and a co-author on the paper, told KUOW that parents should not blame themselves or breastfeeding for the chemical findings. "The problem is not breast milk," Babadi said, adding that families "cannot shop their way out" of exposures that are baked into modern supply chains. Babadi and co-authors continue to recommend breastfeeding while pushing for broader, systemic fixes that cut down the flow of these compounds into people’s bodies.
KUOW’s reporting also highlights socioeconomic and occupational exposure routes that can increase risks for some workers and communities. One example cited is thermal receipt paper handled frequently by cashiers, a common source of certain bisphenols that can disproportionately affect people whose jobs put them in constant contact with those products.
Washington's regulatory response
Washington state has already started to clamp down on several of the same chemicals identified in the study. The Department of Ecology’s Safer Products for Washington program adopted rules that restrict bisphenol epoxy can liners starting January 1, 2025, and prohibit bisphenols in thermal receipt paper beginning January 1, 2026, according to the Washington Department of Ecology. The Safer Products rules also target phthalates, triclosan in cosmetics, and PFAS in carpets and furniture as part of a broader strategy to phase out certain priority chemicals.
Advocates argue that when a state like Washington sets these kinds of rules, it nudges manufacturers to overhaul product lines in ways that can ripple far beyond state borders.
What parents should know and practical steps
Health guidance for families has not changed. Major medical groups still recommend breastfeeding, with the American Academy of Pediatrics advising exclusive breastfeeding for about six months and continued breastfeeding as complementary foods are introduced, according to the American Academy of Pediatrics.
For parents worried about chemical exposure, experts point to a few practical, low-effort steps that can help reduce contact. Those include washing hands after handling receipts, avoiding heating food in plastic containers, and leaning on fresh or minimally packaged foods when possible, while policymakers and manufacturers work on cutting contamination at its source.
The Department of Ecology has encouraged businesses to switch away from bisphenol-coated receipts and runs reimbursement programs to help small businesses pay for safer receipt systems, according to the Washington Department of Ecology.
Policy hurdles and next steps
Researchers and advocates caution that changing chemical policy is a slow grind. KUOW reports that Washington’s process for restricting new chemicals can take at least five years from start to finish, a timeline co-authors argue is too long when infants are being exposed right now. Even so, the Safer Products rules are held up as one concrete pathway for action.
Scientists say this new breast milk study underscores the need for faster evaluations, broader product restrictions, and better biomonitoring of infant exposures. The research team plans to continue follow-up work to track trends and health outcomes in larger and more diverse populations, with the goal of understanding how these early-life exposures may play out over time.
