Per‐ and poly‐fluoroalkyl substances (PFAS) are a broad class of environmentally persistent chemicals that include thousands of potentially toxic synthetic organic molecules. Some PFAS have been shown to cause adverse health effects including decreased total cholesterol, birth weight, and reproductive success in laboratory animals; however, a lack of chronic toxicity data exists for PFAS in avian ecological receptors. The present study reports on the chronic toxicity of perfluorooctane sulfonic acid (PFOS) and a mixture of PFOS and perfluorohexane sulfonic acid (PFHxS) to northern bobwhite quail (Colinus virginianus) via oral exposure from drinking water. Female weight gain was adversely affected at an average daily intake (ADI) of 3.10 × 10−3 ± 0.15 × 10−3 mg PFOS:PFHxS (1.2:1) mixture × kg−1 body weight × d−1. Successful liberation from the shell once pipped was adversely affected at an ADI of 2.45 × 10−3 ± 0.01 × 10−3 mg PFOS x kg−1 body weight × d−1. These values are comparatively much lower than the current dietary avian toxicity reference value (TRV) derived from birds that were exposed via feed, suggesting the need for updated avian TRVs. Relationships between test chemical (PFOS) and test substance (PFOS:PFHxS) showed that PFOS and PFHxS have possible interacting effects in avian receptors and likely differing mechanisms of toxicity depending on chemical co‐occurrence and dose. Both the single‐chemical and mixture exposures produced similar and possibly additive toxicity values. Environ Toxicol Chem 2020;39:1101–1111. © 2020 SETAC

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To further characterize avian toxicity to environmental levels of select per‐ and poly‐fluoroalkyl substances (PFAS), we established species‐ and tissue‐specific PFAS chronic toxicity values (CTVs) associated with a lowest‐observable–adverse effect level (LOAEL) threshold previously established for northern bobwhite quail (Colinus virginianus) chronically orally exposed via drinking water to either perfluorooctane sulfonate (PFOS) or a simple PFAS mixture. Aided by advances in analytical techniques, the novel avian oral PFAS CTVs reported in the present study are lower than the previously reported toxicity reference values (TRVs) estimated for birds chronically exposed via feed. Thus, current avian PFOS TRVs may not be fully protective of wild avian populations at PFAS‐impacted sites. Also, likely due to differences in bioavailability, bioaccessibility, and toxicokinetics among individual PFAS between oral exposure types, we found higher bioaccumulation factors in all assessed tissues from birds exposed via water versus feed. Thus, we propose that future characterization of chemical toxicity due to ingestion exposure initially include a full examination of all probable sources of oral exposure for the most accurate derivation of TRVs and a more complete picture of ecological risk. The avian PFAS LOAEL CTVs established in the present study can be modified with the use of uncertainty factors to derive site‐specific avian TRVs for ecological risk assessment at PFAS‐impacted sites. From differences observed in the behavior of PFOS when administered as either a single chemical or part of a binary mixture with perfluorohexane sulfonate (PFHxS), we verified that PFOS was absorbed and distributed differently when coadministered with PFHxS and that PFOS likely interacted with PFHxS differently among tissues, helping to explain the differences observed in avian toxicity between exposures. Environ Toxicol Chem 2021;40:899–909. © 2020 SETAC

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Terrestrial toxicology data are limited for comprehensive ecotoxicological risk assessment of ecosystems contaminated by per‐ and polyfluoroalkyl substances (PFAS) partly because of their existence as mixtures in the environment. This complicates logistical dose–response modeling and establishment of a threshold value characterizing the chronic toxicity of PFAS to ecological receptors. We examined reproduction, growth, and survival endpoints using a combination of hypothesis testing and logistical dose–response modeling of northern bobwhite quail (Colinus virginianus) exposed to perfluorohexanoic acid (PFHxA) alone and to PFHxA in a binary mixture with perfluorooctane sulfonic acid (PFOS) via the drinking water. The exposure concentration chronic toxicity value (CTV) representative of the lowest‐observable–adverse effect level (LOAEL) threshold for chronic oral PFAS toxicity (based on reduced offspring weight and growth rate) was 0.10 ng/mL for PFHxA and 0.06 ng/mL for a PFOS:PFHxA (2.7:1) mixture. These estimates corresponded to an adult LOAEL average daily intake CTV of 0.0149 and 0.0082 µg × kg body weight–1 × d–1, respectively. Neither no‐observable–adverse effect level threshold and representative CTVs nor dose–response and predicted effective concentration values could be established for these 2 response variables. The findings indicate that a reaction(s) occurs among the individual PFAS components present in the mixture to alter the potential toxicity, demonstrating that mixture affects avian PFAS toxicity. Thus, chronic oral PFAS toxicity to avian receptors represented as the sum of the individual compound toxicities may not necessarily be the best method for assessing chronic mixture exposure risk at PFAS‐contaminated sites. Environ Toxicol Chem 2021;40:2601–2614. © 2021 SETAC

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A variety of veterinary pharmaceuticals and pesticides are used on beef cattle feed yards to enhance growth and health of cattle and to control unwanted pests and parasites. Because growth promoters and antibiotics have recently been detected on particulate matter emanating from feed yards, we examined wildflowers collected near feed yards in the Southern Great Plains for the occurrence of antibiotics, β-agonists, other feed yard-related agrochemicals, and neonicotinoids used on regionally grown row crops. Wildflowers contained detectable concentrations of moxidectin, abamectin, monensin, ractopamine, and neonicotinoids (imidacloprid, thiamethoxam, and clothianidin). All wildflower samples contained at least one target analyte, while the majority (82%) contained multiple pharmaceuticals and/or pesticides, including 12% of wildflowers containing moxidectin, monensin, ractopamine, and a neonicotinoid. This preliminary survey demonstrates the potential for insect pollinators occurring near feed yards to become exposed to mixtures of agrochemicals derived from beef cattle feed yards and pesticides from row crop-based agriculture.