Hydroquinone-d4 (Quinol-d4) is the deuterium labeled Hydroquinone (HY-B0951). Hydroquinone (Quinol, 1,4-Benzenediol) is an antioxidant that can be used as a dye, an engine fuel, and a synthetic intermediate in the production of oil. Hydroquinone is a major benzene metabolite. Hydroquinone is able to enhance carcinogenic risk by generating DNA damage. Hydroquinone promotes tumor cell growth and suppresses the immune response. Hydroquinone induces apoptosis in neutrophils and eosinophils via the mitochondrial apoptosis pathway (Caspase 9/3). Hydroquinone shows increased toxicity for aquatic organisms, being less harmful for bacteria and fungi[1].