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A multi-omics approach was utilized to identify altered biological responses and functions, and to prioritize contaminants to assess the risks of chemical mixtures in the Maumee Area of Concern (AOC), Maumee River, OH, USA. The Maumee AOC is designated by the United States Environmental Protection Agency as having significant beneficial use impairments, including degradation of fish and wildlife populations, bird or animal deformities or reproduction problems, and loss of fish and wildlife habitat. Tree swallow (Tachycineta bicolor) nestlings were collected at five sites along the Maumee River, which included wastewater treatment plants (WWTPs) and industrial land-use sites. Polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), polycyclic aromatic hydrocarbons (PAHs), polychlorinated dibenzo p dioxins and furans (PCDD/Fs), and chlorinated pesticide concentrations were elevated in Maumee tree swallows, relative to a remote reference site, Star Lake, WI, USA. Liver tissue was utilized for non-targeted transcriptome and targeted metabolome evaluation. A significantly differentially expressed gene cluster related to a downregulation in cell growth and cell cycle regulation was identified when comparing all Maumee River sites with the reference site. There was an upregulation of lipogenesis genes, such as PPAR signaling (HMGCS2, SLC22A5), biosynthesis of unsaturated fatty acids (FASN, SCD, ELOVL2, and FADS2), and higher lipogenesis related metabolites, such as docosapentaenoic acid (DPA), docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), and arachidonic acid (AA) at two industrial land-use sites, Ironhead and Maumee, relative to WWTP sites (Perrysburg and SideCut), and the reference site. Toledo Water, in the vicinity of the other two industrial sites and also adjacent to a WWTP, showed a mix of signals between industrial land-use and WWTP land-use. PAHs, oxychlordane, and PBDEs were determined to be the most likely causes of the differentiation in biological responses, including de novo lipogenesis and biosynthesis of unsaturated fatty acids., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Tree swallows (Tachycineta bicolor) nesting near oilsands development in northern Alberta are potentially exposed to elevated levels of metals. The objective of this study was to determine whether levels of metals and metalloid elements in dietary items and tissues of nestling tree swallows inhabiting areas near oilsands mine operations were higher compared to those of reference sites. We hypothesized that if there was increased, industry-related exposure to metals, it would be via the diet. We identified the invertebrate prey in the stomach contents of nestlings. We also collected invertebrates using Malaise traps near nest boxes, and analyzed those taxa found in the nestling diet to understand potential variability in metal exposure. For most elements, we found no significant differences in concentrations in the liver, kidney, or stomach contents between sites near to and far from oilsands operations. Concentrations of five elements were positively correlated among tissues and stomach contents. For invertebrates collected from Malaise traps, location differences occurred in some absolute elemental concentrations, which were most often highest at reference sites away from mining operations. We found no evidence that nestling tree swallows accumulated metals approaching toxic levels. Tree swallows consumed relatively high quantities of terrestrial insects, possibly limiting exposure to water borne, food-web-related contaminants. We suggest that annual variability associated with elemental exposure and dietary levels of elements be considered when interpreting concentrations in bird tissues., (Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.)