4631 Hydroquinone Hydroquinone, also benzene-1,4-diol, is an aromatic organic compound which is a type of phenol. Hydroquinone is commonly used as a biomarker for benzene exposure. The presence of hydroquinone in normal individuals stems mainly from direct dietary ingestion, catabolism of tyrosine and other substrates by gut bacteria, ingestion of arbutin containing foods, cigarette smoking, and the use of some over-the-counter medicines. In human medicine, hydroquinone is used as a topical application in skin whitening to reduce the color of skin. In 2006, the United States Food and Drug Administration revoked its previous approval of hydroquinone and proposed a ban on all over-the-counter preparations. The FDA stated that hydroquinone cannot be ruled out as a potential carcinogen. This conclusion was reached based on the extent of absorption in humans and the incidence of neoplasms in rats in several studies where adult rats were found to have increased rates of tumours, including thyroid follicular cell hyperplasias, anisokaryosis, mononuclear cell leukemia, hepatocellular adenomas and renal tubule cell adenomas. Numerous studies have revealed that hydroquinone can cause exogenous ochronosis, a disfiguring disease in which blue-black pigments are deposited onto the skin, if taken orally; however, skin preparations containing the ingredient are administered topically. The FDA has classified hydroquinone currently as a safe product, as currently used. (Wikipedia) 123-31-9 785 C6H6O2 110.11 Hydroquinone is a white granular solid at room temperature and pressure. 172.3 °C 286°C (546.8°F) 72.0 mg/mL at 25 °C 3, not classifiable as to its carcinogenicity to humans. (L135) Hydroquinone has a variety of uses principally associated with its action as a reducing agent which is soluble in water. It is a major component in most photographic developers where, with the compound Metol, it reduces silver halides to elemental silver. In human medicine, hydroquinone is used as a topical application in skin whitening to reduce the color of skin. 2014-09-05T17:10:15Z 2026-05-14T19:06:26Z Hydroquinone C00530 17594 236-TRICHLOROHYDROQUINONE DB09526 HQE true OC1=CC=C(O)C=C1 C6H6O2 InChI=1S/C6H6O2/c7-5-1-2-6(8)4-3-5/h1-4,7-8H QIGBRXMKCJKVMJ-UHFFFAOYSA-N 110.1106 110.036779436 Exogenous Solid 0.59 HMDB02434 CHEMBL537 764 Miyanohara, Isao; Yanagihara, Tadahisa. Hydroquinone. Jpn. Kokai Tokkyo Koho (1977), 4 pp. CHEM003537 DTXSID7020716 NS00004421 benzene-1,4-diol 40.46 30.0198 10.751706760439284 0 2 2 9.676283592749463 -5.887165947200477 0 1 0.71 -0.06 9.55e+01 g/l