The Agency for Toxic Substances and Disease Registry (ATSDR) is soliciting research to commence a multi-site study on the human health effects of exposures to drinking water contaminated with per- and polyfluoroalkyl substances (PFAS). Proposed study sites must include communities using PFAS-contaminated private residential wells or public water systems. Exposure assessment will be based on measured PFAS serum levels as well as estimated PFAS serum levels derived from pharmacokinetic modeling of reconstructed PFAS drinking water concentrations over time. Specifically, grant awardees will be required to conduct historical reconstruction/water modeling in order to determine the PFAS concentration. Effect biomarkers such as lipids and tests of immune and thyroid function derived from pharmacokinetic modeling of reconstructed PFAS drinking water concentrations over time will be evaluated. ATSDR intends this research to be a two-part program consisting of (1) a mandatory core research protocol to allow ATSDR to aggregate the core data and to compare laboratory and statistical analyses across sites, and (2) each successful awardee will have the option to propose additional investigator-initiated research questions and hypotheses related to the overall goals of this NOFO.