Combined developmental toxicity of organophosphorus flame retardant TCEP and lead on zebrafish

The rise in electronic waste from the electronics industry has increased environmental and health risks. Pollutants like tris(2-chloroethyl) phosphate (TCEP) and lead (Pb) are particularly concerning for their harmful effects on aquatic life and human health. In the current study, zebrafish were exposed to Pb (190 μg/L) and TCEP (350, 3500, 35000 μg/L) from 4 to 120 hours post-fertilization. Mortality, hatching rate, spinal curvature, and spontaneous movement were observed. qRT-PCR was used to detect neurodevelopmental gene expression. Neurotransmitter levels (serotonin, dopamine, acetylcholine) were measured by ELISA, Pb absorption by ICP-MS, and metabolic changes by metabolomics. Our results indicated that lower doses of TCEP and Pb had no significant effect on spinal curvature or movement. However, high-dose TCEP (35000 μg/L) combined with Pb (190 μg/L) significantly increased spinal curvature (P < 0.001), inhibited movement (P < 0.05), decreased body length (P < 0.01), and reduced heart rate (P < 0.01). Gene expression related to spinal and neurodevelopment was downregulated (P < 0.05), and 5-HT levels increased (P < 0.05). The combined effect of Pb and TCEP was synergistic. Metabolomics showed differential metabolites in lipid pathways, with significant increases in pld1 and pld2 gene expression (P < 0.05). In conclusion, High-dose TCEP combined with Pb exposure synergistically affects early zebrafish development, particularly the spine and nervous system, potentially through glycerophospholipid metabolism and the phospholipase D signaling pathway.