5. Castor Oil
Any big fan of the hit television series Breaking Bad would probably know that castor beans can be used to make ricin, a particularly potent poison. In fact, one single castor bean contains enough ricin to kill more than 1,000 people! Although castor oil is normally prepared properly and does not contain any poison, be cautious of manufacturers that do not have a proven track record of producing a safe product. One little slip-up when working with castor beans could easily end up being fatal.