Ricin is one of the most dangerous toxins found in nature. Depending on how you take up the substance, even small quantities amounting to less than a milligram is fatal.
According to the Robert Koch Institute (RKI), the toxic effect can occur orally, through the skin, the stomach and inhalation. Injected, inhaled or swallowed, the colorless and odorless poison prevents the body from producing vital proteins. Once the body is exposed to the poison, ricin binds to sugar molecules that are attached to the surfaces of the body cells.
Symptoms of poisoning like high fever, drop in blood pressure, increased heart rate, vomiting and bloody diarrhea are delayed. As a result, the central nervous system, kidneys, liver and other organs fail. Ricin can also paralyze the respiratory tract; death from cardiovascular shock or organ failure occurs within a few days.
According to RKI, the incubation period depends on the dose and the way in which one comes into contact with the poison — i.e. whether via the respiratory tract, the stomach or the skin. The first symptoms appear after only a few hours after oral intake, usually within 48 hours. So far there is no official antidote. There are only a few people in the world who are immune to ricin.
Origin of the organic weapon
The poison is found in the seeds of Ricinus communis, the castor bean or castor oil plant. Castor is indigenous to the southeastern Mediterranean Basin, Eastern Africa and India, but is widespread throughout tropical regions. The castor oil plant protects its seeds from predators with ricin.
The reddish-brown, bean-shaped seeds of the castor beans are not dangerous in themselves, even if a child has put a bean in his mouth or swallowed it, the poisoning is usually mild. This is because only a small amount of the poison is released from an intact seed. Only when the child has chewed the bean or has it in his stomach for a long time can an increased release of the poison occur.
The castor oil is actually extracted from the tree's seeds. The highly laxative oil is non-toxic and is used in medicine and cosmetic products. The poison itself is therefore more likely to be obtained from what remains from oil production. The poison can only be inhaled or injected when it is isolated and processed accordingly.
'Potential biological agent'
RKI classifies ricin as a "potential biological warfare agent." As early as World War I, the United States tested how ricin could be used as a weapon, for example whether ammunition could be prepared with the poison. In addition, experiments were conducted on how to use dust to spread ricin so that it is inhaled.
Such military experiments were only discontinued after World War II — other chemical weapons were simply even more effective. Ricin is still subject to the global biological and chemical weapons conventions. Trade and handling of the pure substance have been restricted since 1997.
Despite the efforts, ricin has been used several times as a weapon. A particularly spectacular case occurred in London in 1978, when Bulgarian dissident Georgi Markov was murdered in full public view. Markov was allegedly stabbed in the leg with an umbrella by an agent of the Bulgarian secret service. There was a pellet of the poisonous ricin in the tip of the umbrella. Three days later, Markov was dead.
What makes ricin so attractive in terms of bioterrorist attacks is the fact that it is relatively easy to obtain: more than one million castor oil seeds are to be processed every year worldwide. Accordingly, the poison has already been found in the possession of extremist outfits all over the world, including right-wing groups in the US and al Qaeda’s wing in Yemen.
The Tunisian man recently arrested in Cologne had come across security authorities because of conspicuous internet purchases. Among other things, the man bought 1,000 castor oil seeds and an electric coffee grinder from an internet mail order company.