Ricin is extremely toxic and can be used to make biological weapons. So why is castor still grown in large quantities?

A friend asked: Why is castor oil plant still planted even though it is a biological weapon?

I told him that except for you, probably no one would say that castor is a biological weapon. But if ricin is extracted from castor, it may become a biological weapon.

Toxicity of ricin

Ricin is a highly toxic plant protein that is mainly found in castor seeds. Its toxicity mainly damages the liver, kidneys and other organs, causing bleeding, degeneration, necrosis and other lesions, leading to failure; it can also dissolve red blood cells, inhibit and paralyze the cardiovascular and respiratory centers, and cause death.

That is to say, after ricin is injected, inhaled or ingested, the toxin enters human cells and prevents the human cell ribosomes from producing protein. Without protein, the cells will die, causing widespread organ damage and ultimately death from failure.

Unrefined castor beans are also highly toxic. Generally, children taking 2 to 7 seeds may be poisoned and die, while adults taking 20 seeds may be fatal. Different species of castor beans have different toxicity. Castor beans grown in Africa are the most toxic, and 2 seeds can kill an adult. However, there are also reports that adults can survive after eating 24 seeds. This is only an individual case, so I advise everyone not to try it.

The extracted ricin is extremely toxic. The median lethal dose for mice is 2.7μg (micrograms)/kg (kilogram body weight) for intravenous injection and 7~10μg/kg for intraperitoneal injection. In other words, just a few micrograms per kilogram of body weight can kill a person. What is the concept of micrograms? 1g (gram) is equal to 1000mg (milligrams) or 1000000μg. Usually 1 gram of a substance is about the size of a little fingernail, and 1 microgram is one millionth of a gram, which is almost invisible.

For a 70 kg adult, even if calculated at 10 micrograms per kilogram of body weight, the lethal dose is only 0.7 mg. According to some cases, it is far less than that, as long as about 0.5 mg enters the human body, it can cause death. In other words, 1 gram of ricin (about the amount of a fingernail) can kill about 2,000 people.

Many reports on the Internet believe that ricin is 6,000 times more toxic than cyanide, twice as toxic as cobra venom, and 385 times as toxic as VX. This is terrifying, but it seems a bit exaggerated.

Because cyanide is also very toxic, the oral lethal dose of sodium cyanide and potassium cyanide is 1-2 mg/kg body weight; the oral lethal dose of hydrocyanic acid is 0.7-3.5 mg/kg, and the concentration of hydrocyanic acid in the air as long as it reaches 0.3 mg/L (liter) can be fatal. Compared with the lethal dose of ricin, which is about 5 ug/kg, it is only a few hundred times, not that big a difference.

So, is ricin a biological weapon?

The so-called biological and chemical weapons include biological weapons and chemical weapons.

Biological weapons use biological warfare agents to generate lethality, resulting in the destruction and death of enemy manpower or animals and plants. Biological warfare agents are active microorganisms such as rickettsia, viruses, toxins, chlamydia, fungi, etc., which are placed in special weapons facilities and released to local camps to kill humans and animals and destroy crops and plants.

Today we will mainly talk about castor oil and will not go into details about biological weapons.

Strictly speaking, ricin can be used as a raw material for chemical weapons. Ricin is a plant glycoprotein extracted from castor beans, with a molecular weight of 66,000. It is a cytotoxic toxin and consists of two polypeptide chains, A and B, connected by a disulfide bond.

Its mechanism of action is as follows: when the toxin enters the human body, the A and B chains separate, and the A chain enters the cytoplasm by permeating the cell membrane, causing the ribosomes of the eukaryotic cells to lose activity, thereby inhibiting protein synthesis; the B chain binds to the cell surface, produces an internalization effect, and drills into the cell, prompting the A chain to enter the cytoplasm.

Due to the strong toxicity of ricin, the United States studied the use of ricin as a bullet coating during World War I. As long as the bullet hits the human body, or the bullet fragments splash the human body and scratch the epidermis, it will cause death. However, due to the violation of the declaration of the 1899 Hague Convention prohibiting the use of poisonous projectiles, this research was not used later.

However, ricin has always been favored by many countries, and they always want to use it in weapons. During World War II, some countries wanted to make ricin into poison gas bombs, but the production cost was much higher than other nerve gases, such as VX and sarin, and it was difficult to cause large-scale casualties. It had no advantages, so it was difficult to use it as a weapon of mass destruction.

But this does not mean that ricin has never been used for military purposes. Due to some of its significant advantages, such as stable toxicity and the fact that its properties and effectiveness are not affected by acid or alkali factors, many countries still have a special liking for it, and it was later mainly used as an assassination weapon in espionage warfare.

Typical cases of ricin killings

The most talked-about spy warfare case, which has been adapted into film and television many times, is the ricin murder case that occurred on the streets of London in 1978.

On September 11, 1978, BBC reporter Markov was going to work and coming home as usual. He was leisurely waiting for the bus at a bus stop to go home. Suddenly, he felt a sharp pain in his thigh. He subconsciously looked up and saw a man leaving with an umbrella. It seemed that he was accidentally touched by the umbrella. Markov did not investigate further. At this time, the bus came and he got on the bus and returned home smoothly.

But soon after returning home, Markov began to have a high fever and was immediately sent to the hospital by his family for treatment. However, his condition did not improve, but continued to worsen, and he died three days later. (There is still no effective antidote for ricin poisoning)

This bizarre death case attracted great attention from the British police. The forensic doctor conducted a detailed examination of Markov's body and found a very inconspicuous small wound on his thigh, which looked like a small bite from a small insect. However, the forensic doctor found a small hollow platinum ball in the wound, with a diameter of 1.7 mm. There were two tiny holes on the surface of the ball, and there were traces of wax seals on the holes.

The British Biological Warfare Center then participated in the investigation. After the cooperation of experts and the police, they finally found out the cause of Markov's death: ricin caused his death. The small metal ball was shot by a special air gun disguised as an umbrella. The small hole was filled with high-purity ricin. When the metal ball shot through Markov's pants and drilled into his leg muscles, the small hole sealed with wax was opened, and the venom penetrated into the body's blood, causing his death by poisoning.

Who was Markov and why was he assassinated by spies? It turned out that Markov was a famous writer in Bulgaria. Because he often criticized the authorities, he was labeled as an anti-government person and persecuted. He was forced to flee to the UK. However, the Bulgarian authorities did not let him go, but sent agents to chase him and put him to death.

After the end of the Cold War, the Bulgarian archives were declassified and it was publicly acknowledged that the assassination was carried out by agents. The agents sent out injected 0.45 mg of ricin into Markov with a special umbrella, killing him.

Cases involving ricin have been happening from time to time. Why has ricin been so popular among criminals and terrorists? This is because the raw material for making ricin is castor beans, which are easy to obtain and extremely toxic. Even a small amount can be fatal.

In 2019, a Pentagon spokesman said that two emails containing ricin were received, addressed to the Secretary of Defense and the Secretary of the Navy, but fortunately they were discovered in advance and no one was harmed; on September 19, 2020, the FBI claimed that it had intercepted an email containing ricin addressed to US President Trump and arrested several suspects for this; the British MI6 also discovered ricin and raw materials and equipment used to produce the toxin in London, and arrested six suspects from North Africa.

If ricin is so toxic, why is castor oil plant grown everywhere?

This is because castor oil plant has strong adaptability and is resistant to cold, heat, saline-alkali, barrenness, and heavy metal pollution. It can be grown almost anywhere in the world and has extremely high economic value and soil and water conservation value. It is one of the top ten oil crops in the world.

Castor oil is a high-grade industrial oil with the characteristics of severe cold and high temperature resistance. It can withstand -18℃ without freezing, and will not change, deteriorate or burn at high temperatures of 500~600 degrees. It is a high-grade lubricant in high-tech industries such as aviation, aerospace, and high-speed machinery.

Castor oil can be hydrolyzed, neutralized and separated to obtain sebacic acid, which is an important raw material for plastic heat stabilizers and can be used to produce various engineering plastics. Biodiesel prepared from castor oil produces much less pollutants such as carbon monoxide than petrochemical diesel, and is a clean energy that may replace some petrochemical energy in the future.

Castor beans are a treasure from head to toe. Their roots, stems, leaves, and seeds all have different uses and are also a very important traditional Chinese medicine. Therefore, planting castor beans can form a long industrial chain, which plays an important role in promoting social and economic development. How can humans be willing to abandon such a good plant?

Although the whole body of castor is poisonous, it is not as terrible as ricin. Castor is generally cultivated or grows wild in the wild. The most toxic part is its seeds, which are fine as long as they are not eaten by mistake. However, castor seeds are highly toxic after all, and there are reports of people being poisoned by eating a few seeds by mistake. Once again, I advise you not to try it.

Welcome to discuss, thanks for reading.

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