Chronic Per‐/Polyfluoroalkyl Substance Exposure Under Environmentally Relevant Conditions Delays Development in Northern Leopard Frog (Rana pipiens) Larvae

Abstract

Per‐/polyfluoroalkyl substances (PFAS) are pervasive in aquatic systems globally and capable of causing detrimental effects on human and wildlife health. However, most studies are conducted under artificial conditions that are not representative of environmental exposures. Environmental exposures are characterized by multiple routes of exposure, low aquatic PFAS levels, and greater environmental variability than laboratory tests. Determining whether these factors influence toxicity is critical for understanding the effects of PFAS on aquatic life, including amphibians. Our goal was to assess the impact of PFAS on an amphibian under semirealistic conditions. We reared northern leopard frog (Rana pipiens) larvae in outdoor mesocosms containing sediment spiked to low, medium, and high levels (nominally 10, 100, or 1000 ppb dry wt) of perfluorooctanesulfonic acid (PFOS) or perfluorooctanoic acid (PFOA) for 30 d. Larvae in all PFOS treatments and the medium‐PFOA treatment were approximately 1.5 Gosner stages less developed than control animals after 30 d. Notably, these developmental delays were observed at PFOS concentrations in the water as low as 0.06 ppb, which is considerably lower than levels associated with developmental effects in laboratory studies. Our results suggest that deriving toxicity values from laboratory studies examining aquatic exposure only may underestimate the effects of environmental PFAS exposure. Environ Toxicol Chem 2021;40:711–716. © 2020 SETAC

Bioaccumulation, Biodistribution, Toxicology and Biomonitoring of Organofluorine Compounds in Aquatic Organisms

“…Similarly, in tadpoles of R. pipiens exposed for 40 days to three different concentrations of PFOS, PFHxS, PFOA, and 6:2 fluorotelomer sulfonate (6:2 FTS) the PFOS, showed higher accumulated levels with BCF ranging from 19.6 to 119.3 while other PFAS had BCF < 1.0 [66]. A similar trend was observed also for BAF and BSAF recently calculated on R. pipiens larvae where PFOS bioaccumulated at a higher rate than PFOA and where BSAF was up to two orders of magnitude lower than BAF [90].…”

Sublethal Effects of Dermal Exposure to Poly‐ and Perfluoroalkyl Substances on Postmetamorphic Amphibians

“…In conclusion, the present study demonstrates that PFAS have sublethal effects on postmetamorphic amphibians. When combined with PFAS studies on larval amphibians (Palmer and Krueger 2001; Ankley et al 2004; Hoover et al 2017; Brown et al 2020; Flynn et al 2020), this research underscores that PFAS can affect both aquatic and terrestrial life stages of amphibians. Future studies should examine exposure throughout the life cycle, from larvae through adults, to determine the long‐term effects of PFAS exposure on amphibian fitness.…”

Assessing the Ecological Risks of Per‐ and Polyfluoroalkyl Substances: Current State‐of‐the Science and a Proposed Path Forward

“…In American bullfrogs, 96-h LC50 values for PFOS were an order of magnitude lower than for PFOA and effects of the two chemicals in combination appeared additive (Flynn et al 2019 (Foguth et al 2019). An experiment using semi-natural exposure conditions (mesocosms) reported a PFOS 30-d LOEC of 0.06 µg/L based on developmental delays, much lower than that reported for the same species under controlled conditions (10 µg/L) (Flynn et al 2020). A 72-d exposure of American bullfrogs to PFOS, PFOA, and a mixture of the two chemicals showed effects that varied markedly by endpoint.…”