The exposure and effects of perfluoroalkyl substances (PFASs) were studied at eight locations in Minnesota and Wisconsin between 2007 and 2011 using tree swallows (Tachycineta bicolor). Concentrations of PFASs were quantified as were reproductive success end points. The sample egg method was used wherein an egg sample is collected, and the hatching success of the remaining eggs in the nest is assessed. The association between PFAS exposure and reproductive success was assessed by site comparisons, logistic regression analysis, and multistate modeling, a technique not previously used in this context. There was a negative association between concentrations of perfluorooctane sulfonate (PFOS) in eggs and hatching success. The concentration at which effects became evident (150-200 ng/g wet weight) was far lower than effect levels found in laboratory feeding trials or egg-injection studies of other avian species. This discrepancy was likely because behavioral effects and other extrinsic factors are not accounted for in these laboratory studies and the possibility that tree swallows are unusually sensitive to PFASs. The results from multistate modeling and simple logistic regression analyses were nearly identical. Multistate modeling provides a better method to examine possible effects of additional covariates and assessment of models using Akaike information criteria analyses. There was a credible association between PFOS concentrations in plasma and eggs, so extrapolation between these two commonly sampled tissues can be performed.

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Preferential biomagnification of 14 dioxin-like polychlorinated biphenyls (PCBs) was determined in lower-trophic-level organisms of the Lake Michigan, USA, food web. Bioaccumulation of these coplanar, aryl hydrocarbon hydroxylase (AHH)-inducing PCB congeners and total PCBs in phytoplankton, zooplankton, Mysis relicta, and Diporeia sp. were studied for two locations in Lake Michigan over time. The results indicate that both total PCB and AHH-inducing PCBs biomagnify with increasing food web trophic level, with biomagnification of the AHH-inducing PCBs occurring to a greater degree. The biomagnification factors (BMFs) of the AHH-inducing PCBs suggest that they are highly conserved relative to other PCB congeners. The concentrations expressed as dioxin toxic equivalencies (TEQ concentrations) indicate that the biomagnification of AHH PCBs causes greater concentrations, and thus greater toxicity risk, with increasing trophic level.

A great blue heron (Ardea herodias) colony on Pig's Eye Island on the Mississippi River near St. Paul, Minnesota, USA, is located near several potential perfluorinated compound (PFC) sources. The PFC concentrations in great blue heron eggs reported from a 1993 collection from the Pig's Eye colony were among the highest measured in bird eggs worldwide. The objective of this investigation was to determine whether PFC concentrations in great blue heron eggs at the Pig's Eye colony have changed since 1993. Total PFC concentrations in great blue heron eggs collected at the Pig's Eye colony in 2010 and 2011 (geometric mean=340 and 492 ng/g wet wt) were 60% lower than the 1993 collection (1,015 ng/g wet wt). Among PFCs, perfluoroalkyl sulfonate concentrations were lower and perfluoroalkyl carboxylate concentrations were higher in the 2010 and 2011 collections. Two of 20 (10%) of the eggs analyzed from Pig's Eye in 2010 and 2011 were >1,000 ng PFCs/g wet weight and the maximum PFC value (2,506 ng PFCs/g wet wt) measured in 2010 and 2011 was among the highest PFC concentration reported in bird eggs. These high concentrations are at levels associated with physiological and neurological effects in birds.