Date of Award

January 2026

Document Type

Open Access Thesis

Degree Name

Master of Public Health (MPH)

Department

School of Public Health

First Advisor

Valery Danilack-Fekete

Second Advisor

Nicole Deziel

Abstract

Background: Per- and polyfluoroalkyl substances (PFAS), including PFOA and PFOS, may reach infants through breast milk and water used to reconstitute infant formula. However, current U.S. evidence is limited, and the absence of nationally representative breast milk PFAS data constrained estimation of early-life infant exposures.Methods: This thesis developed a state-level exposure modeling framework to estimate daily infant PFOA and PFOS intake across U.S. states at 3 and 6 months of age. Modeled intake included two feeding pathways, breast milk and formula-reconstitution water, using national maternal serum PFAS concentrations, state-level public drinking water PFAS concentrations, and infant feeding distributions. A total of eight scenarios were generated by varying high and low PFAS drinking water concentrations, serum-to-milk transfer ratios, and infant consumption rates. Associations between breastfeeding prevalence, reliance on private wells, and PFAS drinking-water policy context, and modeled infant intake were examined, and sensitivity analyses were conducted using alternative assumptions regarding WIC-based feeding allocation and private well water use. Results: Public drinking water PFAS concentration was the main driver of modeled infant intake across states. At median PFAS concentrations in drinking water, most states were dominated by the breast milk pathway, with limited variation in intake. At the 95th percentile, a smaller subset of states shifted toward formula-reconstitution water as the dominant pathway, with higher modeled intake. Exclusive breastfeeding prevalence was not strongly associated with modeled intake at median PFAS water concentrations, but a slight inverse association was observed at the 95th percentile. Private well reliance was not clearly associated with modeled intake. States with enforceable regulations or numeric limits had higher modeled PFOA intake, while PFOS associations were weaker, and region-adjusted estimates were less precise. Sensitivity analyses showed a very high agreement between WIC-based allocation and the primary estimates, while private well adjustment produced minimal changes in overall estimates. Conclusion: This thesis provided estimates that informed early-life PFAS exposure assessment and future risk assessment.

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This is an Open Access Thesis.

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