Impact of early-life F-53B exposure on skeletal development of zebrafish offspring

Per- and polyfluoroalkyl substances (PFAS), especially the newly adopted chlorinated polyfluoroalkyl ether sulfonate (6:2 Cl-PFESA, trade name F-53B), have raised significant concerns because of their environmental persistence and potential toxicity. This has prompted the need to evaluate their effects on vertebrate development, particularly skeletal formation. The aim of this study is to investigate the impact of early-life exposure to F-53B on the skeletal development of zebrafish offspring. Initially, we established the median lethal concentration (LC₅₀) of F-53B at 15.21 μg/mL through a 96-hour exposure experiment. Based on this, we set a maximum treatment concentration of 10 μg/mL for further investigations. Subsequently, zebrafish embryos exposed from fertilization exhibited marked developmental deformities at 10 days post-fertilization (dpf), including a 23.3% incidence of spinal curvature and stunted growth. Alcian blue and alizarin red staining showed significant reductions in cartilage and bone development compared to controls. Reactive oxygen species (ROS) staining revealed a significant increase in ROS fluorescence intensity compared to the control group. Quantitative real-time PCR (qPCR) indicated downregulation of oxidative stress genes (cat, mt2, and sod1), osteogenic genes (alp, ocn, and runx2a), and chondrogenic genes (sox9b, col1a1a, and col2a1a) in treated groups. These findings indicate that early-life exposure to F-53B can induce developmental abnormalities in zebrafish offspring, particularly spinal curvature, and adversely affect both cartilage and bone development. This may be related to F-53B inducing dysregulation of gene expression in offspring zebrafish skeletal development through oxidative stress. Future research should further elucidate the underlying molecular mechanisms and long-term implications of such exposure on skeletal health.