Chronic Exposure to a PFAS Mixture Resembling AFFF Causes Decreased Body Size in Northern Leopard Frogs

<p>Per- and polyfluoroalkyl substances (PFAS) occur in the environment as mixtures, yet mixture toxicity remains poorly understood. Aqueous film-forming foams (AFFF) are a common source of PFAS. Our objective was to examine chronic effects of a complex PFAS mixture on amphibian growth and development. We tested toxicity of a five-chemical PFAS mixture summing to 10 mg/L and that accounts for >90% of the PFAS in AFFF-affected surface waters: perfluorooctane sulfonate (PFOS, 40%), perfluorohexane sulfonic acid (PFHxS, 30%), perflurooctanoic acid (PFOA, 12.5%), perfluorohexanoic acid (PFHxA, 12.5%), and perfluoropentanoic acid (PFPeA, 5%). We also included treatments to determine whether PFOS drove mixture toxicity and whether PFOS and mixture components act additively. We exposed Northern leopard frog (<em>Rana</em> <em>pipiens</em>) larvae through metamorphosis (~120 d) in outdoor mesocosms. After 21 days of exposure, larval body condition fell ~5% relative to controls in the 4 mg/L PFOS treatment and mixtures lacking PFOS. At metamorphosis, the full 5-component 10 mg/L PFAS mixture reduced mass by 16% relative to controls. We did not observe effects on development. Our results indicate that toxicity of PFOS and other PFAS mixtures typical of AFF sites act additively and that PFOS is not more inherently more toxic than other mixture components. The data structure is described in detail in the data dictionary, above.</p>