2-Ethyl-Hexyldiphenyl Phosphate (EHDPP) Induces Cytotoxicity by Activation of Autophagy Process in HepG2 Cells

Organophosphate flame retardants (OPFRs) are extensively used in the electronics industry, plastics, textiles, and other sectors to reduce flammability and enhance fire safety. However, excessive OPFR use has led to significant environmental accumulation, increasing ecological stress and potential human health risks. This study investigates the effects of 2-ethylhexyldiphenyl phosphate (EHDPP) on HepG2 cells, demonstrating that EHDPP exposure impairs normal cellular function through excessive autophagy, ultimately reducing cell viability. Our findings reveal a concentration-dependent decline in cell survival, with an LC₅₀ of 120 μM. While lower concentrations (0, 1, 5, 10, and 50 μM) exerted minimal effects, 50 μM EHDPP significantly reduced cell viability. Further analysis confirmed that EHDPP exposure upregulates autophagy-related genes (ATG5, ATG12, VPS34, Beclin1, FIP200, ATG13, and ATG3), leading to an increased LC3-II/I ratio and a decrease in p62 levels, indicative of enhanced autophagic activity. Transmission electron microscopy (TEM) imaging confirmed a substantial increase in autophagosome formation at 50 μM EHDPP. These results provide new insights into the cytotoxic mechanisms of EHDPP, emphasizing its role in triggering excessive autophagy in hepatic cells.