Toxicity Effects of Dibutyl Phthalate on Embryonic and Juvenile Stages of Japanese Medaka (Oryzias latipes)

• • Exposure to 5 mg·L−1 DBP significantly reduced embryonic heart rate (P < 0.0001), causing 100% hatching failure and mortality, indicating a lethal threshold for early-life-stage fish. • • At 500 μg·L−1 DBP, hatching rate and survival rate were significantly reduced (P < 0.01 and P < 0.0001, respectively), demonstrating sublethal developmental toxicity at environmentally relevant concentrations. • • DBP exposure induced dose-dependent malformations including cardiovascular hemorrhage, spinal curvature, and yolk sac edema, with significant inhibition of larval swimming behavior, compromising fitness and survival. • • Molecular analyses revealed significant upregulation of oxidative stress genes (cat, gpx2, gsta) and estrogenic markers (vtg1, erβ1, chgl), alongside downregulation of neuroendocrine genes (trha, mbp, elavl3), indicating multi-system toxicity at transcriptional level.