The oil of castor bean seeds is used as a laxative, in the preparation of some foods and to make paints for artists. The castor bean seeds themselves are extremely poisonous. The poison, ricin, needs to be removed from the seeds before the oil can be used.
Heating the oil from castor bean seeds will also destroy any ricin that remains.
Women have also used castor bean seed oil as contraception, and it's been employed since ancient times to dress wounds. It's used in perfumes and soaps, and it is also applied as a lubricant in the motors of cars and aircraft, although it's been largely replaced by synthetic oils.