(CNN) -- Ricin is a natural, highly toxic compound that is one of the byproducts of processing castor beans.
If inhaled, injected or ingested, less than a pinpoint of ricin can kill a person within 36 to 48 hours due to the failure of the respiratory and circulatory systems. There is no known cure.
One molecule of ricin will kill a cell it enters.
Ricin ingestion is not always fatal. Children are at more risk than adults.
If ingested, ricin causes nausea, vomiting and internal bleeding of the stomach and intestines, followed by the failure of the liver, spleen and kidneys, and finally death by collapse of the circulatory system.
If a castor bean seed is swallowed whole without damage to the seed coat, it will probably pass harmlessly through the system. But if the coat is chewed or broken, then swallowed, the poison will enter the body.
If injected, ricin causes the immediate death of the muscles and lymph nodes near the site of the injection. Failure of the major organs and death usually follows.
Medical experts point out that ricin is nowhere near as powerful a killer as anthrax.