Ricin

CAS RN: 9009-86-3

Exposure Summary

Ricin's production and use in research in the treatment of cancer may result in its release to the environment through various waste streams. Its illicit use as a bioterrorism weapon will result in its direct release to the environment. Ricin is a glycoprotein consisting of two polypeptides, termed A and B chains, which are linked by disulfide bonds. The A chain contains 265 amino acids and the B chain contains 260 amino acids. Ricin is present in the seeds of Ricinus communis (Castor bean) and Croton tiglium (Purging croton). Ricin comprises approximately 1 to 5% of the weight of the castor bean mash that remains after oil extraction. The castor plant occurs in practically all tropical and subtropical countries and is also grown annually from seed as an ornamental and as cultivated plants in temperate zones. If released in air, low micron-sized particles may stay suspended in undisturbed air for many hours and resuspension of settled low micron-sized particles from disturbed surfaces can occur. Ricin has a UV max of 280 nm and, therefore, is not expected to be susceptible to direct photolysis by sunlight. Ricin is very stable and to a great extent not affected by extremes in heat or cold environmetnal temperatures. Ricin is soluble in water and stable over a wide range in pH. Under both the 1972 Biological and Toxin Weapons Convention and the 1997 Chemical Weapons Convention, ricin is defined as a Schedule One controlled substance which is toxic by ingestion, inhalation, and injection. An accidental exposure to ricin is unlikely. The general population may be exposed to ricin by ingestion or inhalation as the result of an act of bioterrorism. (SRC)
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