Source:http://linkedlifedata.com/resource/umls/id/C0005047
NCI: A grayish-red, yellowish or white colored, very toxic, crystalline aromatic amine that darkens when exposed to air and light. Benzidine has been widely used for the detection of blood and as a reagent in the manufacture of dyes. Ingestion of benzidine causes cyanosis, headache, mental confusion, nausea and vomiting. Its use is now limited because of strong association between exposure to benzidine and an increased risk of bladder cancer in humans. (NCI05)