Trends and Patterns of Perfluoroalkyl Substances in Blood Samples of Bald Eagle Nestlings in Wisconsin and Minnesota, USA.

We analyzed concentrations and trends of perfluoroalkyl substances (PFAS) in blood plasma samples of bald eagle (Haliaeetus leucocephalus) nestlings at 6 study areas in the upper Midwest of the United States, 2006 to 2015, and long-term trends at 2 Lake Superior sites, 1995 to 2015. Nestling blood plasma concentrations of the sum of 15 PFAS analytes (∑PFAS) differed among study areas and were highest at the 3 industrialized river sites: Pools 3 and 4 of the Mississippi River (Pools3+4; geometric mean [GM] =754 μg/L; range = 633-2930), the Mississippi National River and Recreational Area (MISS; GM = 687 μg/L; range = 24-7371), and the lower St. Croix National Scenic Riverway (LSACN; GM =546 μg/L; range = 20-2400). Temporal trends in ∑PFAS in nestling plasma differed among study areas; concentrations decreased at Pools3+4, MISS, and LSACN, but not at the most remote sites, the upper St. Croix River and Lake Superior. Overall, perfluorooctanesulfonate (PFOS) was the most abundant analyte at all study areas, and perfluorodecanesulfonate (PFDS) the second-most abundant at industrialized river sites though not at Lake Superior; concentrations of both these analytes declined from 2006 to 2015 over the study area. In addition, nestling age significantly influenced plasma concentrations of ∑PFAS and 7 of the 12 analytes. For these analytes, concentrations increased 1 to 2% per day as nestlings grew, indicating that age should be considered when using nestling plasma to assess PFAS. This article is protected by copyright. All rights reserved.