OECD 425–Based Acute Oral LD 50 Evaluation of 4‐Methylimidazole in Female Swiss Albino Mice

ABSTRACT 4‐Methylimidazole (4‐MI) is a heterocyclic compound generated during thermal food processing and industrial applications, raising toxicological and regulatory concern due to its widespread exposure. This short communication reports the acute oral toxicity of 4‐MI in female Swiss albino mice using the OECD Test Guideline 425 (up‐and‐down procedure). Sequential dosing revealed no mortality at 175 mg/kg, whereas administration of 550 mg/kg resulted in rapid neurotoxic signs followed by death within minutes. The median lethal dose (LD 50 ) was estimated as 310 mg/kg body weight (95% CI: 175–550 mg/kg). Based on the estimated LD 50 , 4‐MI would correspond to USEPA toxicity Category II and GHS Category 4 classifications. The findings indicate the presence of rapid neurobehavioral alterations suggestive of central nervous system involvement, thereby justifying the need for further applied toxicological investigations, and also demonstrate that OECD 425 is a suitable and ethically compliant approach for acute toxicity assessment.