This data package constitutes the ecotoxicology evidence used to assess contaminant loads in the breast muscle tissues of hunter-harvested migratory waterfowl collected in the Northeast Atlantic Flyway during the 2021-2022 hunting season. This package contains three folders: (1) Waterfowl Sample (Field) Collection Metadata Folder, (2) Analytical Chemistry Data Folder, and (3) Final Contaminant Data Folder. Content in the Waterfowl Sample (Field) Collection Metadata Folder was produced while obtaining samples of wild waterfowl from hunters across the study area. Content in the Analytical Chemistry Data Folder was originally compiled, curated, and provided by contracted analytical facilities to the Wildlife Health Laboratory at Cornell University (CWHL), after which CWHL did minimal data cleaning (converted formats, removed redundant columns). Specifically, analytical chemistry data on mercury (Hg) originated from raw data provided by the New York State Department of Environmental Conservation Analytical Services Unit at the Hale Creek Field Station (Gloversville, New York); polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs) originated from raw data provided by Pace Analytical (Minneapolis, Minnesota); and polychlorinated biphenyls (PCBs), E1 and E2 organochlorine pesticides (OCPs), and per- and polyfluoroalkyl substances (PFAS) originated from raw data provided by SGS AXYS (Sidney, British Columbia). Content in the Final Contaminant Data Folder was processed according to our specific project decisions regarding concentrations (see below and annotations in code for details) for publication in Dayan et al. (in preparation).