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A 22-year-old with a history of allergic rhinitis and childhood asthma presents to your office for evaluation. He noticed a flulike illness with low-grade fever, congestion, watery itchy eyes, and dry cough 1 week earlier soon after he arrived at work. The symptoms resolved by midweek and he felt fine through the weekend. On Monday morning he noticed the same constellation of symptoms, but this time he developed hives and by midafternoon he felt quite short of breath. He works as a maintenance worker at a local manufacturer of castor oil for the automotive industry. His job involves removing the mash residual following processing of the castor plants. He has no significant cardiac history and is a nonsmoker. Because he was frankly wheezing and very dyspneic, you referred him to the local emergency room. You inform the ED that you suspect he may be having an allergic reaction to or even frank ricin intoxication from his work. As neither you nor the ED is familiar with this syndrome, you recommend that the attending contact the Poison Control Center regarding diagnostic testing and treatment.

Ricin is a protein derived from Ricinus communis, a plant whose bean produces a natural laxative “castor oil” long known for its medicinal value and the bane of American school children through much of the 20th century. Ricin’s toxic properties were first identified in the 19th century. After castor oil is extracted from the bean, ricin remains in the residual mash and can easily be separated out. Ricin is not found in castor oil itself. Each year, approximately a million tons of castor beans are involved in industrial uses primarily to extract the oil for use as a lubricant in aerospace machinery. Such a figure represents an annual availability of 50,000 tons of industrial ricin byproduct and making it a viable BCN threat.

Ricin has played valuable roles both in the development of medical knowledge and as a therapeutic agent. At the end of the 19th century, experimentation with ricin laid the groundwork for understanding the mechanisms of immune response in regards to antibody stimulus and specificity. Ricin, owing to its antitumor effect, has been used as a chemotherapeutic agent. In recent years it has been of interest in the development of monoclonal antibodies in cancer treatment, as well as for treatment of chronic pain syndromes. Processing of castor plants industrially is also associated with occupational illness and disease. Castor bean dust or castor oil are organic compounds and may induce a typical allergic syndrome consisting of upper airway irritation, urticaria or rashes, and even reactive airways or frank asthma. Occupational exposure to plant mash also puts workers at risk for the toxic syndromes to be summarized in the following sections.

Ricin has a notorious history as a weapon of war and espionage as well. Ricin can be manufactured cheaply and easily, and it is a highly potent phytotoxin. Ricin first became of interest at the ...

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