Ricin is a highly potent toxin that is produced in the seeds of the castor oil plant, Ricinus communis. It is a poison that can be made from the waste left when castor beans are made into castor oil. Ricin is a lectin, which is a carbohydrate-binding protein. The median lethal dose (LD50) of ricin for mice is around 22 micrograms per kilogram of body weight via intraperitoneal injection. Oral exposure to ricin is far less toxic, and an estimated lethal oral dose in humans is approximately 1 milligram per kilogram of body weight.

Ricin can be in the form of a powder, a mist, or a pellet, or it can be dissolved in water or weak acid. It is a stable substance and does not break down easily in typical indoor or outdoor temperatures. Ricin can be used to poison people by putting it in food or water, and if liquid or powdered ricin is released into the air, people could be poisoned by inhaling it. If it’s mixed with a solvent, it can be absorbed through the skin. Ricin can also be used to poison an individual person by injecting it.

Symptoms of ricin poisoning depend on the route of exposure. Within a few hours of inhaling significant amounts of ricin, the likely symptoms would be respiratory distress (difficulty breathing), fever, cough, nausea, and tightness in the chest. Heavy sweating may follow, as well as fluid building up in the lungs (pulmonary edema). This would make breathing even more difficult, and the skin might turn blue. Finally, low blood pressure and respiratory failure may occur, leading to death. If someone swallows a significant amount of ricin, he or she would develop vomiting and diarrhea that may become bloody. Severe dehydration may result, followed by low blood pressure. Other signs or symptoms may include hallucinations, seizures, and blood in the urine. Within several days, the persons liver, spleen, and kidneys might stop working, and the person could die. Ricin in powdered or mist form can cause redness and pain of the skin and of the eyes.

There is no cure or antidote for ricin poisoning. Prompt medical care is essential, and care could include such measures as helping victims breathe, giving them intravenous fluids, giving them medications to treat conditions such as seizure and low blood pressure, flushing their stomachs with activated charcoal (if the ricin has been very recently ingested), or washing out their eyes with water if their eyes are irritated.