Castor oil taken internally is not toxic. It has been used in the US as a folk remedy for any number of complaints. In fact, I was given large amounts in a smoothie to assist in natural childbirth inducement.
What you may have heard is that the castor bean itself IS toxic. In fact, it contains the deadly poison ricin. However, the oil has been refined to take out the ricin and is a perfectly safe purgative laxative.
I can tell you from personal experience that it is POWERFUL!