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Synonyms: Ricinus communis lectin, ricin D, ricin toxin
Contaminant Type: Chemical

Ricin is a potent protein that acts as a toxin if inhaled, injected, or ingested. Ricin can be used as a chemical warfare agent and has been weaponized in the past; however, it is not considered practical nor likely to be a significant threat in drinking water. [1275]

Ricin has a molecular weight of about 63,000 Da and consists of two polypeptide chains (termed A and B) linked through a single disulfide bond. [1319]  Ricin inhibits protein synthesis. The B-chain binds to cell surface receptors and the toxin-receptor complex is taken into the cell. The A-chain then inhibits DNA replication and protein synthesis.

Ricin is easily extracted from castor-oil manufacturing waste material left from processing castor beans (Ricinus communis). Waste materials are approximately 3% to 5% ricin by weight [1306]. Ricin is easily purifed from this waste using simple chromatographic techniques. Approximately 1 million tons of castor beans are processed annually; precursor materials for ricin are readily available in large quantities throughout the world. Purified ricin can be in the form of powder, a mist, or a pellet, which can be dissolved in water. Ricin can be used as a chemical warfare agent in the past.

When ingested, ricin can cause severe gastrointestinal symptoms including nausea, vomiting, and diarrhea, followed by vascular collapse and possible death [1312].

Ricin is inactivated much more readily than other biochemical agents, such as botulism and anthrax. (The protein changes structure and becomes less toxic). Because ricin is significantly less toxic by oral ingestion than by other routes, it is a less credible threat in drinking water [1275].

Although ricin is easy to produce, it is not considered practical nor likely to be used in drinking water as a weapon to cause significant military or civilian casualties. Ricin is not regulated by USEPA in drinking water. Little is known about ricin occurrence in drinking water sources.

Date of Literature Search: June 2009

1275 Burrows, W. and Renner, S.; 1999; Biological warfare agents as threats to potable water; Environ Health Perspect; 107:12:975
1306 Franz, D.; 1997; Defense Against Toxin Weapons; Medical Aspects of Chemical and Biological Warfare; Chapter 30. pp 603-619.
1312 Salem, H., Whalley, C., Wick, C., Gargan, T., Burrows, D., Romano, J. (Ed.), Lukey, B. (Ed.) and Salem, H. (Ed.); 2008; Chemical Warfare Agent Threat to Drinking Water ; Chemical Warfare Agents: Chemistry, Parmacology, Toxicology and Therapeutics; Chapter 3. pp. 51-70. CRC Press, Boca Raton.
1319 Yamasaki, N., Hatakeyama, T. and Funatsu, G.; 1988; Denaturation of ricin D in frozen aqueous solutions; Agricultural and Biological Chemistry; 52:10:2547