Hexamethylphosphoramide-d18 is the deuterium labeled Hexamethylphosphoramide (HY-Y1155). Hexamethylphosphoramide is an orally active polar aprotic solvent, flame retardant additive, and carcinogen. Hexamethylphosphoramide undergoes cytochrome P-450-mediated N-demethylation to Formaldehyde. Hexamethylphosphoramide induces DNA-protein crosslinks. Hexamethylphosphoramide has been linked to nasal tumors (squamous cell carcinoma, adenoid squamous cell carcinoma), squamous metaplasia, rhinitis, tracheitis, and reversible and irreversible infertility[1][2][3][4][5][6][7][8].