Ricin inhalation toxicity

Griffiths, G.D., Rice, P., Allenby, A.C., Bailey, S.C., Scawin, J.W., Rice, P., Upshall, D.G. (1995a). Inhalation toxicology and histo-pathology of ricin and abrin toxins. Inhal. Toxicol. 7 269-88. Griffiths, G.D., Rice, P., Allenby, A.C., Bailey, S.C., Scawin, J.W., Rice, P., Upshall, D.G. (1995b). Protection against inhalation toxicity of ricin and abrin by immunisation. Hum. Exp. Toxicol. 14 155-64. 

Documented cases of human poisoning by ricin aerosol exposure are unknown. Cautious inferences may be drawn from observations of NHP exposed to ricin under controlled laboratory settings. Human toxicity from ricin inhalation would be expected to occur after a latency period of 24—72 h that may be characterized by loss of appetite and listlessness. Based on extrapolation from NHP studies, other signs and symptoms expected in humans after ricin inhalation may include listlessness, high fever, dyspnea, and coughing or bloody sputum that is delayed for 4—8 h after exposure, as well as bilateral abnormalities on chest radiographs, arterial hypoxemia, neutrophilic leukocytosis, and elevated protein levels in bronchial aspirates (Balint, 1974 Wilhelmsen and Pitt, 1996 Franz and Jaax, 1997). 

Griffiths GD, Lindsay CD, Allenby AC et al. (1995b). Protection against inhalation toxicity of ricin and abrin by immunisation. Human Exp Toxicol, 14, 155-164. 

Ricin is a large, moderately toxic, protein dichain toxin from the bean of the castor plant, Ricinis communis. It can be produced easily in relatively large quantities. Ricin was developed as a biological weapon by the United States and its allies during World War II. Although ricin is toxic by several routes, when inhaled as a respirable aerosol, it causes severe necrosis of the airways and increased permeability of the alveolar-capillary membrane. The inhalational route... 

Abrin, a potent toxin, is extracted from the seeds of the rosary pea (Abrus precatorius). Due to its easy availability and preparation, this toxin is an attractive option for weap-onizing in poor countries, and thus has also been included in the Sch ule 1 of the CWC. The mechanism of action of abrin is very similar to that of ricin however, in mice, abrin is 75 times more toxic than that of ricin (0.04 pg/ kg for abrin is equivalent to 3pg/kg of ricin). Similar to ricin, inhalation of abrin is found to be more toxic than ingestion. However, abrin ingestion has reported to be toxic to the liver, unlike ricin. At the cellular level, abrin is a potent toxalbumin known to cause cell death by inhibiting protein synthesis (namely, type 2 ribosomal inhibitory protein). Further, abrin is also known to induce endothelial cell damage leading to an increase in cell permeability, fluid and protein leakage, and tissue edema. 

Caution Ricin is extremely toxic to cells and acts by inhibiting protein synthesis. After aerosol exposure, signs and symptoms would depend on the dose inhaled. Humans can be expected to develop severe lung inflammation with progressive cough, dyspnea, cyanosis, and pulmonary edema. 

Movement of the biological material ricin with soil-size fractions are shown in Figures 4.6 and 4.7. Studies on peanut (Arachis hypogaea) seed lectin show similar results (Zartman et al. 2005). These lectin data are similar in distribution to published values (Ravi et al. 2004). The inhalation of dust generated from ricin-contami-nated soils could pose a serious hazard to war fighters. Work of A. H. Corwin cited in Lamanna (1961) stated that ricin particles with a median diameter of 2 /(ui are 2.75 times as toxic as particles with a maximal particle size of 4.2 pm. 

Ricin is markedly less toxic to animals by the Gl route than it is by parenteral injection or inhalation. In laboratory mice, for example, the acute LD50 for ricin exposure intragastrically or orally (p.o.) has been reported to be 1-20 mg/kg (Parker et al., 1996), which is 100- to 1000-fold less toxic than by... 

It is is the third most toxic substance known after plutonium and botulism it is a protein toxin that is extracted from the castor bean (Ricinus communis). The USA Centers for Disease Control (CDC) considers 500 pg to be the lethal dose of ricin in humans if exposure is from injection or inhalation. Ricin is poisonous if inhaled, injected, or ingested, acting by the inhibition of protein synthesis. While there is no known antidote, the US military has developed a vaccine. 

A. Characteristics. Ricin is a glycoprotein toxin from the seed of the castor bean plant. Altering ribosomal RNA blocks protein synthesis, thereby killing infected cells. Ricin s significance as a potential biological warfare agent relates to its availability worldwide, ease of production, and extreme pulmonary toxicity when inhaled. 

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... 

Toxicity of ricin also varies with route of challenge. In laboratory mice, the approximate dose that is lethal to 50% of the exposed population (LD50) and time to death are, respectively, 3 to 5 pg/kg and 60 hours by inhalation, 5 pg/kg and 90 hours by... 

As is the case in toxicity and pathogenesis of intoxication, the route of exposure is important in relation to possible modes and their likelihood of success of prophylaxis and therapy. For oral intoxication, supportive therapy includes activated charcoal administration and intravenous fluid and electrolyte replacement. For inhalational intoxication, supportive therapy to counteract acute pulmonary edema and respiratory distress is indicated. Symptomatic care is the only intervention presently available to clinicians for the treatment of incapacitating or lethal doses of inhaled ricin. Positive end-expiratory ventilatory therapy, fluid and electrolyte replacement, antiinflammatory agents, and analgesics... 

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