Ricin inhalation, effects

Candidate vaccines under development are immunogenic and confer protection against lethal aerosol exposures. Recent animal studies have shown that either active immunization or passive prophylaxis may be effective against intravenous or intraperitoneal intoxication with ricin (Poh et al, 1994). In the case of inhalational exposure, active immunization or prophylactic administration of aerosolized specific anti-ricin antibody may also be effective (Poli et al, 1994). Unfortunately, these applications may not be clinically available since they are still under investigation. 

There is normally a delay of several hours between the exposure to ricin and the onset of clinical symptoms, but the cytotoxic effects may not occur until two to five days after ingestion. In contrast, certain individuals may display allergic reactions almost immediately after exposure, and this is presumed to be related to the glycoproteins that the beans contain. Episodes of asthma have been linked to the inhalation of ricin dust at castor bean mills — in one incident in 1952 at Bauru in Brazil, 150 people living close to a bean mill were affected by sudden asthma attacks. 

Ricin is more toxic by inhalation than by ingestion. The symptoms from inhaling aerosolized ricin are weakness, fever, cough and pulmonary edema. Such effects may onset after a latent period of 8 hours. Death can result in 36 to 72 hours from severe respiratory distress. The toxin binds... 

Specific effects of ricin poisoning depend on whether ricin was inhaled, swallowed, or injected. 

No antidote exists for ricin. Ricin poisoning is treated by giving the victim supportive medical care to minimize the effects of the poisoning. The types of supportive medical care would depend on several factors, such as the route by which the victim was poisoned (that is, by inhalation, ingestion, or injection). Care could include such measures as helping the victim breathe and giving him or her intravenous fluids and medications to treat swelling. 

Ricin is not an infectious agent but rather is a potent protein toxin produced from castor beans (Figure 3.5). Castor beans are common worldwide and the toxin is easy to produce. It makes a good bioweapon (better for assassination than for mass exposure) because it is stable and can be administered by several routes (inhalation, oral, or injection). Although ricin is not as deadly as some toxins, the ease of its production makes it attractive as a weapon. It has been especially attractive for small terrorist organizations that lack funds for obtaining more deadly weapons. Aerosol would be the most effective delivery method, but it is difficult to produce ricin particles in the 5-micron range so it is less useful for mass exposures. 

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