Longitudinal trends of per- and poly-fluoroalkyl substances (PFAS) in nestling bald eagles (Haliaeetus leucocephalus) from Wisconsin.

We analyzed concentrations and trends of per- and polyfluoroalkyl substances (PFAS) in 96 nestling bald eagles (Haliaeetus leucocephalus) at six study sites throughout Wisconsin from 2011 to 2017. Nestling blood plasma concentrations of the sum of 11 PFAS analytes (∑ PFAS) differed among study locations: the highest concentration was in the industrialized Green Bay region at study area: Upper Green Bay/Lake Michigan (GBLM; estimated mean = 313.18 μg/L; range = 188.3-478.9 μg/L). For study locations with only one year of data, PFAS were highest at downstream Wisconsin River sites: Lower Wisconsin State River (LWSR; estimated mean = 646.7 μg/L; range 376.0-979.8 μg/L) and Middle Wisconsin River (MDWR; 659.6 μg/L; range = 209.3-928.6 μg/L). Overall, perfluoroctanesulfonate (PFOS) was the most abundant analyte at all study locations. Perfluoroundecanoate (PFUnDA) and perfluorodecanoate (PFDA) were the second and third highest concentration analytes at most sites. Temporal trends existed for ∑ PFAS and all analytes for most of the study locations with more than one year of data - with patterns for analytes differing by study location. In addition, nestling age significantly altered plasma concentrations of ∑ PFAS and PFOS - concentrations were higher in older nestlings, ranging from 3.77 to 4.38 μg/L per day of age difference, respectively. We have illustrated that bald eagles can be useful and reliable bioindicators of PFAS exposure and environmental change. The results from this study can be used by management and conservation agencies to highlight locations of concern that could be prioritized for remediation.