Title: Cadmium
CAS Registry Number: 7440-43-9
Literature References: Cd; at. wt 112.411; at. no. 48; valence 2. Group IIB (12) element. Abundance in earth's crust: 0.1 to 0.2 ppm. Naturally occurring isotopes (mass numbers): 114 (28.73%); 112 (24.13%); 111 (12.80%); 110 (12.49%); 113 (12.22%), T½ 9.3 ´ 1015 yrs, b-emitter; 116 (7.49%); 106 (1.25%); 108 (0.89%); known artificial radioactive isotopes: 97-105, 107, 109, 115, 117-122, 124, 126. Found in zinc ores; also as CdS, greenockite; CdCO3, otavite. Obtained in vapor form when roasting zinc ores, as sludge from zinc sulfate purification. Lab prepns from CdSO4: Treadwell, Helv. Chim. Acta 4, 551 (1921). Implicated as causative agent in Itai-Itai ("ouch-ouch") disease in Japan: Flick et al., Environ. Res. 4, 71-85 (1971); Fassett, Annu. Rev. Pharmacol. 15, 425-435 (1975). Review: Aylett "Group IIB" in Comprehensive Inorganic Chemistry vol. 3, J. C. Bailar Jr. et al., Eds. (Pergamon Press, Oxford, 1973) pp 187-328; D. S. Carr in Kirk-Othmer Encyclopedia of Chemical Technology vol. 4 (John Wiley & Sons, New York, 4th ed., 1992) pp 748-760; N. Herron, ibid. 760-776. Review of carcinogenic risk: IARC Monographs 11, 39-74 (1976); and toxicity: Cadmium in the Human Environment: Toxicity and Carcinogenicity, IARC Scientific Publ. 118, G. F. Nordberg et al., Eds. (1992) 469 pp; of toxicology and human exposure: Toxicological Profile for Cadmium (PB99-166621, 1999) 439 pp.
Properties: Silver-white, blue-tinged, lustrous metal; distorted hexagonal close-packed structure; easily cut with a knife; available in the form of bars, sheets or wire or a gray, granular powder. mp 321°. bp 765°. d25 8.65. Specific heat at constant pressure (25°) 6.22 cal/mole deg. Slowly oxidized by moist air to form CdO. E° (aq) Cd/Cd2+ 0.4025 V. Insol in water. Reacts readily with dil HNO3; reacts slowly with hot HCl; does not react with alkalies. Other reactions similar to those of zinc. Solns of cadmium salts and H2S or Na2S yield a yellow ppt insol in excess Na2S.
Melting point: mp 321°
Boiling point: bp 765°
Density: d25 8.65
CAUTION: Overexposure to cadmium and cadmium compounds has been associated with acute and chronic toxicity. Potential symptoms of acute poisoning from the inhalation of cadmium dusts or fumes include headache, chest pains, cough, metal fume fever, weakness. Potential symptoms of acute poisoning from ingestion of cadmium salts are GI disturbances, headache, muscular cramps, vertigo, convulsions. Chronic inhalation may cause pulmonary emphysema and chronic bronchitis. See Clinical Toxicology of Commercial Products, R. E. Gosselin et al., Eds. (Williams & Wilkins, Baltimore, 5th ed., 1984) Section II, p 99; Section III, p 77-84. Potential toxic effects due to chronic overexposure by inhalation or ingestion are anemia; kidney damage; osteomalacia and osteoporosis. Itai-itai disease is a skeletal disease associated with a cadmium-induced renal disorder and is attributed to high oral intake of cadmium in food and water; characterized by progressive bone demineralization with painful joints and bones. See Patty's Industrial Hygiene and Toxicology vol. 2C, G. D. Clayton, F. E. Clayton, Eds. (John Wiley & Sons, New York, 4th ed., 1994) p 1954-1967. See also NIOSH Pocket Guide to Chemical Hazards (DHHS/NIOSH 97-140, 1997) p 44. Cadmium and cadmium compounds are listed as known human carcinogens: Report on Carcinogens, Eleventh Edition (PB2005-104914, 2004) p III-42.
Use: Batteries, including Ni-Cd storage batteries; coating and electroplating steel and cast iron; pigments; plastic stabilizers; constituent of low melting or easily fusible alloys, e.g., Lichtenberg's, Abel's, Lipowitz', Newton's, and Wood's metal; electronics and optics; soft solder and solder for aluminum; reactor control rods; hardener for copper; catalytsts.
Therap-Cat-Vet: Many cadmium salts, especially the oxide and anthranilate, are used or have been suggested as anthelmintics in swine and poultry. |