ABSTRACT: Perfluoroalkyl substances (PFAS) are a class of synthetic chemicals that are persistent in the environment. Due to concerns linked with longer chain PFAS, shorter chain chemicals were used as replacements, but developmental toxicity assessments of the shorter chain chemicals are limited. The aim of this study was to compare the developmental toxicity of three perfluoroalkyl acids (PFAAs): perfluorooctanoic acid (PFOA), composed of 8 carbon (C8), perfluorohexanoic acid (PFHxA, C6), and perfluorobutanoic acid (PFBA, C4) using the zebrafish (Danio rerio). LC50s at 120 hour post fertilization (hpf) were determined to assess the potency of each PFAA by exposing developing zebrafish (1-120 hpf) to a range of concentrations. In sublethal assessments, zebrafish were exposed to 0, 4, 40, or 400 parts per billion (ppb; µg/L) of the PFAAs throughout embryonic development (1-72 hpf). Effects of the embryonic exposure on locomotor activities was completed with the visual motor response test at 120 hpf. At 72 hpf, morphological changes including total body length, head length, and head width were assessed. Additionally, transcriptomic profiles of PFOA, PFHxA, and PFBA were determined at 72 hpf to compare altered molecular and disease pathways. The LC50 ranking was PFOA > PFHxA > PFBA, which followed trend as expected based on chain length. PFOA caused hyperactivity and PFBA hypoactivity, while PFHxA did not change behavior. PFOA, PFHxA, and PFBA caused morphological and transcriptomic alterations that were unique for each chemical and were concentration dependent. Cancer was a top enriched disease for PFOA, while FXR/RXR activation was a top canonical pathway in all PFBA exposures. Overall, an embryonic exposure to PFOA, PFHxA, or PFBA resulted in morphological alterations in zebrafish eleuthero-embryos; however, only PFOA and PFBA induced neurobehavioral alterations. The transcriptomic profile of each chemical was unique indicating different toxicity mechanisms and were aligned with human adverse health outcomes supporting predictive value.
