The raw castor beans are the most toxic part of this plant, due to its presence of ricin. The leathel dose in adults is considered to be 4-8 seeds, due to this it is sometimes known as the most poisonous plant in the world.
Symptoms of an overdose from ricin, can include nausea, diarrhea, tachycardia, hypotension and seizures persisting for up to a week. If ingested, symptoms may not occur for at least 36 hours although they do commonly begin within 2-4hours.Symptoms of ingestion can include a burning sensation in mouth and throat, abdominal pain, purging and bloody diarrhoea. Within several days severe dehydration may occur, a drop in blood pressure and a decrease in urine. Unless treated, death can be expected to occur within 3–5 days, however in most cases a full recovery can be made.
Poisoning occurs when animals, including humans, ingest broken seeds or break the seed by chewing: intact seeds may pass through the digestive tract without releasing the toxin. Toxicity varies among animal species: four seeds will kill a rabbit, five a sheep, six an ox or horse, seven a pig, and eleven a dog.