Evaluation of Castor Oil Samples for Potential Toxin Contamination

Castor oil and its derivatives are widely used as a chemical feedstock for production of lubricants and greases, engineering plastics, plasticizers and surfactants. It also has wide application in consumer goods such as lipstick, deodorants and medicinal uses. Due to concerns about the possible presence of the ricin toxin in the oil, we have tested a collection of castor oils processed using different approaches, including cold‐pressed, US Pharmaceutical (USP) grade, and neutralized oils. Water soluble proteins were extracted from oil samples into phosphate‐buffered saline containing 0.05 % bovine serum albumin (PBSB) and analyzed for potential ricin contamination by ELISA. Our results indicate that only the cold‐pressed castor oil contained measurable levels of the toxin, estimated to be 35 ± 13 μg/l. A normal oral dose of castor oil for laxative use is 14 ml, so even cold‐pressed castor oil would be well below the toxic level of 1–5 μg/kg body weight. However, the presence of the toxin indicates that other soluble proteins, including allergens, may be present in cold‐pressed castor oil.