Toxicity Effects of Dibutyl Phthalate on Embryonic and Juvenile Stages of Japanese Medaka (Oryzias latipes)
Dibutyl phthalate (DBP) is a ubiquitous environmental pollutant posing potential risks to aquatic ecosystems. This study assessed the developmental toxicity of DBP in Japanese medaka (Oryzias latipes) embryos. Embryos were exposed to gradient DBP concentrations (1, 5, 50, 500 μg·L−1, and 5 mg·L−1) for 15 days. Endpoints included embryonic heart rate, hatching time, survival rate, larval swimming behavior, and expression of genes related to cardiovascular, nervous, thyroid, antioxidant systems, and estrogenic effects. Results showed that 5 mg·L−1 DBP significantly reduced embryonic heart rate (P < 0.0001), leading to hatching failure and mortality. Exposure to 500 μg·L−1 DBP significantly reduced hatching rate (P < 0.01) and survival rate (P < 0.0001). DBP exposure caused developmental delay, cardiovascular hemorrhage, spinal curvature, yolk sac edema, and inhibited larval swimming behavior. At the molecular level, DBP significantly altered expression of atrap, dkk1, bnpa, fx, and dvl mRNA, affecting cardiovascular development; downregulated trha, mbp, and elavl3 mRNA, indicating endocrine disruption and neurotoxicity; upregulated cat, gpx2, and gsta mRNA, inducing oxidative stress; and upregulated vtg1, erβ1, and chgl mRNA, demonstrating estrogenic effects. This study demonstrates that DBP exposure adversely affects growth, development, hatching, survival, swimming behavior, and gene expression in Japanese medaka embryos, highlighting ecological risks of DBP pollution in aquatic environments.