Evaluation of castor oil samples for potential toxin contamination

Authors: McKeon, Thomas; Patfield, Stephanie; He, Xiaohua

Submitted to: Industrial Crops and Products
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/20/2015
Publication Date: 1/4/2016
Citation: Mckeon, T.A., Patfield, S.A., He, X. 2016. Evaluation of castor oil samples for potential toxin contamination. Industrial Crops and Products. 93:299-301.

Interpretive Summary: Castor oil is a key chemical feedstock with numerous applications including surfactants, engineered polymers, plasticizers, lubricants and greases, with lithium grease the most familiar of these products. The oil and its derivatives also have numerous consumer applications including as laxatives, anti-fungal compounds, cosmetics, lipsticks and deodorants. A lubricant industry publication recently suggested that products derived from castor oil may be unsafe due to the presence of toxins, and recommended use of mineral oil for lubricant applications, even though mineral oil is not biodegradeable. We evaluated samples of castor oil that had been subjected to different degrees of processing. None of the well-processed castor oil samples contained any toxin, but the cold-pressed castor oil contained trace amounts, as expected for cold-pressed oils such as peanut oil, which contains trace amounts of peanut allergens. It is therefore safe to use refined castor oils for industry and consumer applications. However, individuals sensitive to castor allergens should exercise caution when using cold-pressed castor oil.

Technical Abstract: Castor oil and its derivatives are widely used as a chemical feedstock for production of lubricants and greases, and for engineering plastics, plasticizers and surfactants. They also have wide application in consumer goods such as lipstick, deodorants and medicinal products. 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 assay. Our results indicate that only the cold-pressed castor oil contained measurable levels of the toxin, estimated to be 35 'g/l ± 13 'g/l. A standard oral dose of castor oil for laxative use is 14 ml, so even cold-pressed castor oil would be well below the toxic level. However, the presence of the toxin indicates that other soluble proteins, including allergens, are likely to be present in cold-pressed castor oil.