The umbrella had been modified to inject a small pellet that contained a lethal toxin. In 1978 Gyorgi Markov, a Bulgarian journalist, was stabbed in the thigh with the tip of an umbrella while waiting at the Waterloo Bridge bus station in London. Markov became ill by evening and died several days later. At autopsy, the pathologist found a sphere with drilled holes, about the size of the head of a pin, embedded in the tissue. The pellet presumably contained ricin. The Cold War had taken another victim by assassination.
The castor bean plant, Ricinus communis, originated in Asia and Africa but has spread to many regions around the globe and is the source of ricin. These perennial shrubs have large, deep-green, divided leaves and produce spiny fruits with mottled seeds resembling an engorged tick. Whereas the outermost shell casing of the plant is used to make castor oil, it is the crushed inner seeds that contain the toxin ricin.
As a toxalbumin, ricin inhibits protein synthesis, thus producing widespread destruction of tissues and organs. Historically ricin has been used in chemical warfare and as an agent for assassination. Ricin can be prepared as a rudimentary plant extract or in powdered, crystalline, or liquid forms, and weapons-grade ricin, made as a payload in artillery shells, was a threat in the Middle East.
Another toxalbumin, abrin, works with the same mechanism as ricin but is more potent. The source of the toxin abrin is the rosary pea or jequirity pea (Abrus precatorius), common to many tropical locations. While all parts of the plant are poisonous, the seeds (bright orange with a small black cap) are primarily implicated in poisoning.
Abrus means “beautiful” and precare means “to pray,” so these seeds or beads were used for ornamental purposes—jewelry, prayer beads—or in maracas (Mexican shaker). The seeds were also utilized historically for weighing gold and jewels in Southeast Asia (1 carat =2 seeds) because of their uniform size. And due to their availability in specific geographic regions, they were unfortunately utilized as a means of suicide in some countries.
However, many poisonings with jequirity peas (and castor beans) are unintentional due to ingesting seeds (or beans). Patients who ingest the crushed jequirity pea seed (whole seeds often pass through the GI tract intact) develop vomiting, diarrhea, and upper abdominal pain. As the abdominal pain progresses, patients produce bloody diarrhea. Central nervous system symptoms include an altered sensorium, seizures, and diffuse cerebral edema with raised intracranial pressure. In later stages, patients present with toxic hepatitis, acute renal failure, and hemolysis.
Abrus precatorius and Ricinus communis are plants with an interesting history. They can be decorative, and even medicinal if prepared correctly. But avoid necklaces, rosaries, and other “jewelry” made with jequirity peas because these can cause unintended poisoning, especially in children. And by all means, beware of anyone following you with an umbrella in hand. The results could be fatal.