Apart from nuclear weapons, which remain one of the greatest threats of the modern era, chemical weapons are those which, by virtue of their power and effectiveness, have the greatest potential to harm human life.
What are we talking about?
The first chemical weapons can be considered to have been used to kill populations on a large scale on April 22, 1915 at Ypres by the Germans, using chlorine on the battlefield. Since then, however, chemical weapons have developed considerably, and we’re going to take a look at the 10 most deadly products.
An historical reminder
In 1855, during the Crimean War, British Admiral Dundonald wanted to reduce the Russian troops at Sevastopol using sulfur vapors, but he didn’t get the go-ahead from his government.
The same goes for the American Doughty, who proposed the use of chlorine gas during the Civil War: he planned to develop shells containing liquid chlorine which, when exploded on the enemy’s head, would flood them with gas. He was also refused by the authorities on moral grounds…
On the other hand, during the Boer War (1899-1902), the British used picric acid as an explosive: its incomplete combustion produced toxic yellowish fumes. The enemy protected themselves by breathing through vinegar-impregnated cloth. The results were insignificant.
So it all began during the 1st World War, when highly toxic products such as chlorine, phosgene and mustard were developed and used.
Then the situation changed little, as these weapons were not used during the Second World War: except for Germany, which developed and used Zyclon B in its gas chambers!
What are the 10 most deadly chemical weapons?
It is difficult to establish a ranking based on objective criteria, but we can take into account their effectiveness on the battlefield and the threat they pose to civilians and military personnel through their intrinsic toxicity.
Starting with the least potent products, we move on to the most lethal.
10- Yperite or mustard gas
The threat to humans is considered moderate.
First used by Germany in WW1, mustard gas is rarely lethal (mortality estimated at 2-10%, but often delayed). It is an incapacitating agent (it has been calculated that, on average, gassed soldiers came back to the front after 42 days). It causes severe burns to the skin, especially as, in its gaseous form, it can penetrate clothing.
Initial symptoms of exposure are generally considered mild to moderate and include runny nose, coughing, skin and eye irritation, sensitivity to light, temporary blindness, sneezing, abdominal pain, diarrhea, nausea, and vomiting. The after-effects are ocular, cutaneous, respiratory, psychological, and genetic.
This gas has a mustard-like odour, hence its name. Once dispersed, the gas is often referred to as a “persistent weapon”, as it remains on the ground for several days (or weeks), depending on weather conditions.
Mustard gas has been used by various states and terrorist groups over the last 100 years. These include the Soviet Union, Iran, Iraq, Sudan, Egypt, Syria and the Islamic State.
9- Benzilate de 3-Quinuclidinyl (BZ)
Developed by the USA, it was first used in 1960, and the threat to humans is considered significant.
Originally developed as a gastrointestinal drug, its side effects on the nervous system were so severe that the army took it over for militarization. Odorless, BZ is an anticholinergic that acts rapidly on the nervous system: within seconds, it causes dizziness, confusion, hallucinations, erratic behavior and loss of basic motor skills. It is a powerful incapacitating agent, acting on the nervous system to reduce intellectual capacity. In high doses, it creates delirium, making intellectual activity impossible.
Because of its ability to inhibit glandular secretions, BZ causes dry mouth and reddening of the skin. In cases of extreme exposure, coma, convulsions, tremors, acute renal failure and death are common.
It has been used on several occasions over the last 40 years, notably by the USA against the Viet Cong during the Vietnam War and by Yugoslav troops against Muslims in Bosnia and Kosovo.
8- Ricin
We have devoted an article to it in this blog [1].
Its potential threat to humans is considered significant. Ricin is a chemical weapon derived from castor beans. It is highly lethal to humans and was first developed by the US army during the First World War, vectorized by toxic bullets or powders. The Soviet Union itself produced various forms of ricin.
Profoundly affected by temperature and weather conditions, dissemination of the substance was very difficult. As a result, ricin was used more for assassinations than for large-scale attacks on troops or populations.
We have already mentioned the assassination of Bulgarian writer Georgi Markov (the so-called Bulgarian umbrella affair) and several international terrorist groups, such as al-Qaeda, have also reportedly tried to use ricin, with limited results.
Inhaled, ricin can cause severe respiratory problems, including coughing, difficult breathing, chest tightness and ultimately respiratory failure within 24 hours. Ingested, ricin symptoms vary considerably and include vomiting, inability to eat or drink, convulsions, acute renal failure, organ failure and complete central nervous system arrest. In both cases, death is common.
7- The chlorine
Its potential threat to humans is considered significant, and we’ve talked about it several times in this blog [2].
It was first used by the German army at Ypres in 1915. Classified as a suffocant, it causes severe lung damage (irreversible effects). Pulmonary edema develops, and death results from asphyxiation.
Chlorine is still used as a chemical weapon by various states and terrorist groups around the world. These include Iran, Iraq and Syria, which has repeatedly deployed this deadly gas against its own population.
6- Phosgene
The threat to humans is considered significant. It is a suffocating agent similar to chlorine, first used by the German army during the First World War.
It produces oropharyngeal pruritus, breathing difficulties followed by acute lung edema and acute respiratory distress syndrome.
Phosgene was first deployed as a chemical weapon by the French in 1915 during the First World War. The gas was also used by the German army on June 22, 1916, during the same conflict, at Verdun, mixed with chlorine, and in the form of a drifting gas wave.
This product was also used between the wars by Japan against the Chinese.
Today, exposure to phosgene is most likely to occur in industry, where it is used to manufacture various pesticides and plastics.
5- Sarin (GB)
The threat to humans is extreme. Like all organophosphates, it is a nerve agent. During the Second World War, 12,000 tonnes of GA (Tabun) and GB (Sarin) were synthesized by Germany, which did not use them.
They are all liquids at normal temperature and pressure. They are highly volatile. Tabun was first used on the battlefield by the Iraqis during the Iran-Iraq war against the Kurds. In 1995, the Aum sect spread sarin in the Tokyo subway [3].
Symptoms of contact with sarin include excessive saliva secretion (hypersialorrhea), breathing difficulties (dyspnea), constricted pupils (miosis), nausea, vomiting, incontinence, loss of consciousness and coma. Death occurs by asphyxiation after a period of convulsion. All nerve agents act by inhibiting acetylcholinesterase, leading to an accumulation of acetylcoline at synapses. The ensuing cholinergic crisis leads to organ hyperstimulation, giving rise to the symptoms described above.
4- Soman (GD)
It is also a G-series nerve agent. Developed by the Germans, this product, whose threat is considered extreme, is even more toxic than tabun and sarin. The liquid is colorless with a camphor-like odor. Highly volatile, it generally disperses within minutes of activation. The threat is immediate but short-lived, as it does not remain in the environment for long.
After contamination, the subject presents vomiting, incontinence, diarrhea, respiratory difficulties and muscular weakness. The victim, overcome by convulsions, sinks into a coma and dies of suffocation within a quarter of an hour of absorbing a lethal dose.
It seems that this product was never used, although some countries synthesized and stockpiled it, particularly during the Cold War.
3- Cyclosarin
It’s a neurotoxic organophosphate: derived from sarin, but more toxic. Unlike sarin, it is a persistent liquid that evaporates relatively slowly (around 69 times slower than sarin), increasing the risk of environmental exposure. Like sarin, cyclosarin causes hypersalivation, dyspnea, miosis, nausea, convulsions and death by asphyxiation.
To date, the only country to have used elea cyclosarin in combat is Iraq, during the Iraq-Iran war.
2- VX
Its threat to humans is considered lethal (it is 10 times more deadly than sarin). It was developed by the British in the 1950s.
Unlike other nerve agents, VX consists of an oily liquid similar in consistency to motor oil. This oily concoction is crucial to its effectiveness as a chemical weapon, as VX has one of the slowest evaporation rates of any existing chemical weapon. This enables it to contaminate a vast area for several days (or even months if conditions are relatively cold).
Symptoms are those of nerve agents, and it can cause death within minutes of exposure. VX is the most toxic nerve agent ever synthesized.
North Korea is known to possess it, since Kim Jong-nam, the brother of North Korean leader Kim Jong-un, was assassinated by this product, which soaked a handkerchief that 2 young women placed over his face.
The Russian equivalent, VR, has been synthesized and stockpiled to the tune of 15,557 tonnes, according to their declaration to the Organization for the Prohibition of Chemical Weapons (OPCW).
1- Novichok agents
Please refer to the following articles: Novichok gas. [4] A NRBCE weapon and Novichok agents: [5] a mini-review of available data.
Like VX, their threat is considered lethal. These products were developed by the Soviet Union between 1971 and 1993. Novichok means “newcomer”.
Their toxicity is around 8 times higher than soman. Novichoks are “binary” weapons. When a new toxic substance is synthesized and tested in the laboratory, its industrial production is developed in such a way that the synthesis of the compound is interrupted before the reaction giving the final product. We are therefore dealing with 2 relatively harmless compounds, stored in separate containers so that they can be transported and stored safely, then mixed just prior to military application.
Novichocks are organophosphate molecules and therefore nerve agents. On March 4, 2018, Sergei Skripal (former Russian military intelligence officer, then British spy) and his daughter Yulia Skripal were poisoned with Novitchok in Salisbury, England. In 2020, Alexei Navalny [6] was the victim of a “Novitchok” assassination attempt.
Towards sophistication
- First war = first generation: Chlorine, mustard gas (Yperite), Lewisite
- 1936-1945= série G des gaz neurotoxiques : Tabun 1936, Sarin 1939, Soman 1945
- 1952 = the V series of organophosphates (V = venom)
- Binary gases
The different classes
- Suffocants: highly volatile gases or liquids that cause serious lung damage (irreversible effects):chlorine, chloropicrin, phosgene;
- Vesicants:mustard, nitrogen mustard, lewisite, rarely fatal but very incapacitating;
- Neurotoxins: organophosphates that inhibit acetylcholinesterase. These are Agents G (for Germany) GA Tabun, GB Sarin, cyclosarin, GD Soman and Agents V (for Venomous) VX, VR , novitchoks ;
- Hemotoxic agents: hydrogen cyanide (HCN) and cyanogen chloride (ClCN); Incapacitating agents: BZ, fentanyl [7]; Irritant agents: of low toxicity, they are used in peacetime: tear gas, sternutatories, urticants;
- Toxins: botulinum toxin, ricin, staphylococcal enterotoxin.
Conclusion
As you can see, the issue of chemical weapons is still very much with us.
The classification of chemical weapons in this article has not been scientifically established, but it reflects the accumulation of a certain amount of data, such as the toxicity of the molecule (LD50), the product’s route of entry, its implementation, its volatility, its ability to persist in the external environment…
This classification can be considered as
“Incorrect but thought-provoking reasoning…”.
These products are closely monitored by the OPCW (Organization for the Prohibition of Chemical Weapons). The Convention on the Prohibition of the Development, Production, Stockpiling and Use of Chemical Weapons and on their Destruction (also known as the Chemical Weapons Convention) was opened for signature at a ceremony in Paris on January 13, 1993. Four years later, in April 1997, the Convention entered into force. One hundred and ninety-three states are committed to the Chemical Weapons Convention – 98% of the world’s population lives under the protection of the Convention – 100% of chemical weapons stockpiles declared by possessor states have been verifiably destroyed.
One state has signed but not ratified: Israel. Three states remain outside the Convention: North Korea, Egypt and South Sudan.
In the next chapter, we’ll look at how to protect ourselves from these products, how to detect them, how to recognize them on the basis of pathological signs in affected patients (toxidromes), and how to eliminate them through decontamination processes.
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