Nature has created some of the deadliest poisons ranging from botulinum neurotoxin and anthrax to ricin. In the fall of 2001, anthrax spores were discovered in the U.S. mail and ultimately resulted in the deaths of five people. This incident raised awareness to the possibility of a terrorist attack using potent, naturally occurring toxins.

Since the fall of 2001, more and more reports of such events have appeared in the media, the latest being the discovery of ricin in a hotel room in Las Vegas in February 2008. Although not new to the world, the use of chemical and biological poisons has raised concerns among law enforcement and forensic laboratories of how to handle and examine potentially contaminated samples.

SOURCES AND PHYSIOLOGICAL EFFECTS
Ricin is a peptide uniquely present in the seed of Ricinus communis (castor oil plant), with a molecular weight between 60-65 kDa, depending on the degree of glycosylation. It is considered the most toxic, plant-derived protein, and is only superseded by the protein botulinum toxin from the bacterium Clostridium botulinum. Despite its toxicity, the perennial shrub Ricinus communis has spread from its indigenous Mediterranean and Eastern African regions throughout the tropical areas of the world, and is widely used as a decorative plant in parks and other public areas. It can be found in the Southern and East coast of the United States (Figure 1). The oil, which is derived from the seeds of the castor oil plant (Photo 1), is widely used as a surfactant and skin conditioning agent in cosmetics. In the process of deriving the oil, ricin is a side product which accumulates in the waste material. A recent study concluded that the use of the seed oil is safe for both cosmetic and medicinal applications.³ Ricin toxicity results from its potent irreversible inhibition of protein synthesis and direct cell damage.⁴ It is water soluble and remarkably stable over a wide pH and temperature range, requiring rigorous conditions (pH below 4 or above11; 80º C for 1h) for its inactivation. Radiation as performed by the postal service does not inactivate ricin and only has a limited effect on the compound. Due to its easy accessibility, potential for mass production, and various routes of dissemination, ricin was considered a chemical warfare agent as early as 1918, and has been associated with bioterrorism attacks around the world. One famous example of ricin poisoning was the assassination of Georgi Markov in 1978 in Great Britain.⁵ Markov was a Bulgarian journalist who criticized the Bulgarian communist regime and had defected from Bulgaria to Great Britain. His death has been attributed to a pellet containing ricin that was shot from the tip of an umbrella. The lethal dose (LD50) of ricin depends on the way it enters the body. The LD50 after oral ingestion is between 1-20 mg/kg or the equivalent of eight castor beans. Although not clearly determined in humans, after both injection and inhalation, the LD50s are much lower at 1-1.75 µg/kg and 21-42 µg/kg, respectively. The symptoms of ricin poisoning are initially nonspecific and include fever, abdominal pain, or chest tightness depending on the route of ingestion. After inhalation, ricin causes cell death in the respiratory system and eventual respiratory failure. If ingested, it can cause severe lesions in the digestive system resulting in abdominal pain, nausea, vomiting, and diarrhea. Eventual complications include cell death in the liver, kidney, adrenal glands, and central nervous system. Injection of ricin causeslocal cell death in muscles, tissue, and lymph nodes at the site of injection. Whichever route of exposure, death results generally within three to five days. If a victim survives this period of time, there is a good chance of survival but with the possibility of permanent organ damage. There is currently no known antidote for ricin poisoning. Symptomatic treatments include fluid compensation, vasopressors, or activated charcoal in case of ingestion. If the poisoned person does not die within three to five days, survival with impaired organ functionality is likely. A vaccine has recently been successfully tested in animals and human volunteers⁶ and might be given to military personnel where biological warfare agents are a potential threat.