All chromates (chromium(VI) or hexavalent chromium) are hazardous materials with great non-cancer human health risks associated with occupational exposure. Certain chromates are known human carcinogens when inhaled. There are three important metabolic reactions involving chromates that can occur in the human body, absorption, reduction, and precipitation. Only doubly charged dissolved chromate ions can be absorbed through epithelial cells (skin, alveoli, erythrocytes, and the small intestine) via non-specific ion channels. Reduction, the conversion of chromate (CrO4 -2) to the non- toxic chromium+3 is favored at lower pHs and in the presence of organic materials such as saliva and mucous and occurs in all organs. Precipitation may occur in the stomach. Epidemiological and toxicological results strongly support the theory that chromates do not cause cancers other than in the lung and lung cancers are associated with the inhalation of insoluble chromates, which are retained in the lung. Includes references, tables.