Benchmark Dose\nEstimation from Transcriptomics Data\nfor Methylimidazolium Ionic Liquid Hepatotoxicity: Implications for\nHealth Risk Assessment of Green Solvents

Ionic\nliquids (ILs), traditionally considered environmentally benign\nsolvents, have shown potential toxicity to organisms, raising concerns\nabout their safety. Among them, 1-octyl-3-methylimidazolium (M8OI)\nhas been detected at high concentrations in soils and exhibits hepatotoxic\nproperties. To uncover the molecular mechanisms underlying this toxicity,\nwhole-transcriptome sequencing was performed, coupled with benchmark\ndose (BMD) modeling, to derive transcriptomic points-of-departure\n(tPOD) through dose–response analysis. The transcriptomic analysis\nidentified 425, 667, and 567 differentially expressed genes (DEGs)\nfollowing low (10 μmol/L), medium (50 μmol/L), and high\n(200 μmol/L) doses of M8OI exposure, respectively. Enrichment\nanalysis revealed significant perturbations in pathways related to\ncytokine–cytokine receptor interaction and IL-17 signaling.\nBMD modeling yielded tPOD values of 1.51 μmol/L (median of the\n20 most sensitive genes, omicBMD<sub>20</sub>), 2.98 μmol/L\n(tenth percentile of all genes, omicBMD<sub>10th</sub>), 6.83 μmol/L\n(mode of the first peak of all gene BMDs, omicBMD<sub>mode</sub>),\nand 5.9 μmol/L for pathway-level analysis. These transcriptomics-derived\ntPODs were at least 105-fold lower than M8OI’s hepatotoxic\nconcentration, as indicated by its EC<sub>50</sub> of 723.6 μmol/L\nin HepG2 cells. Functional analysis of the transcriptomic data identified\nlegionellosis, rheumatoid arthritis, and transcriptional misregulation\nin cancer as the most sensitive pathways affected by M8OI. These findings\nhighlight the molecular mechanisms driving M8OI-induced hepatotoxicity\nand underscore the utility of transcriptomics in deriving sensitive\nand quantitative toxicity thresholds. The results provide critical\ninsights for guideline-driven toxicological evaluations and regulatory\ndecision-making, supporting a more comprehensive assessment of IL\nsafety.