Danielle Crowley investigates mankind’s history of chemical and biological warfare.


Chemical and biological warfare (or CBW for short) isn’t new. The Byzantines created the world’s first flame thrower through the use of Greek fire, a highly volatile substance (the exact components of which have been lost). It could burn on water and was so feared that fully armoured soldiers would rather throw themselves overboard to drown rather than face it in battle. The Romans dumped dead animals into the water supplies of their enemies, and the Mongols catapulted the bodies of plague victims into the besieged city of Caffa in 1346. From the battlefields of World War I to modern day terrorists, from James Bond to BBC’s Sherlock and many science fiction stories in between, CBW has haunted the popular imagination.

But what is the difference between them? What makes them so effective? And are they as dangerous as we have been led to believe?

Firstly, some definitions. Chemical warfare relies on man-made chemicals to kill people. Biological warfare uses bacteria, viruses or toxins to kill people, as the Romans and Mongols did by using corpses. Either way, they are both nasty ways to die.

“Biological warfare has moved on from flinging disease ridden corpses over a wall in the hope that it might infect someone.”


One of the most well-known large scale uses of chemical warfare was during World War I, when mustard gas (first synthesised in 1860) was first used by the Germans in 1917. It affected the eyes (sometimes leading to blindness), caused blisters to erupt on the skin, irritated the respiratory system and induced diarrhoea, vomiting, fever and abdominal pain. Mustard gas, or sulphur mustard, is a blister agent or vesicant, meaning that it damages skin and mucous membranes, which are found in your nose and throat. And if that wasn’t bad enough, it’s also an alkylating agent, which means that the chemicals present within it can destroy DNA and cells and liquefy tissue. Mustard gas wasn’t the only chemical the Allies had to worry about. Chlorine gas, small amounts of which are bubbled through swimming pool water to kill bacteria, was used in 1915 and killed 5000 soldiers by burning the lining of their throats and asphyxiation.

Chlorine and mustard gas are ranked medically as “lethal gases”, meaning that they can cause disablement and death. One other infamous member of this club of killers is sarin. Sarin hit the headlines in 1995 when the Aum Shrinrikyo group released it in the Tokyo metro, resulting in the deaths of thirteen people. Sarin is a nerve agent, meaning that it attacks the nervous system. Specifically, it causes a build up of acetylcholine which leads to overstimulation of nerve cells. This in turn means that the affected person cannot control their breathing, and unless an antidote is administered, death by asphyxiation follows. Even a non-lethal dose can result in permanent damage if medical help isn’t sought out immediately.

The good news is that not all gases used in chemical warfare are lethal. The “Gay Bomb” was envisioned as a non-lethal way to disrupt fighting by using female sex pheromones to make the opposing side sexually attracted to eachother. However it never came out. The group known as “harassing agents” don’t kill (usually) but are used to disrupt enemy soldiers. Or protesters. Or rioters. Or crazy football fans. Tear gas includes an agent that stimulates the hormones that produce tears. Chemical burns, coughing and vomiting may occur. So next time you feel like getting involved in a protest, it would be worthwhile to remember this.

Biological warfare, on the other hand, has moved on from flinging disease ridden corpses over a wall in the hope that it might infect someone. The first “bioterrorism” attacks in the US took place in 2001, where anthrax spores were hidden in envelopes. Five people, four of which were not deliberately targeted, died. A biological weapon using a particularly virulent bacterial or viral strain has the potential to kill thousands, either through aerosol dispersal or through ingestible products like food or medicines. And the natural world has provided us with thousands of toxins which are as fascinating (to scientists at least) as they are deadly.

Botulinum toxin, found in the bacterium Clostridium botulinum, is one of the deadliest substances known to man. It causes paralysis by preventing communication between nerve cells. It is one of the components of Botox and can only survive in the absence of oxygen, such as in soil and sealed jars of meat. Bacteria living in jars of duck paste sandwiches caused the deaths of guests in a Scottish hotel in 1922.

Toxins can severely damage victims’ minds. The year 944 was known as The Great Fear in France due to a fungus called claviceps purpurea, which produces ergot toxin. This toxin killed 40,000 people and as well as causing symptoms such as gangrene, victims also experienced hallucinations and temporary insanity, or permanent insanity depending on how long it took to kill them. LSD is derived from this toxin and was involved in various military experiments in the 1950s aiming to use it as a psychochemical weapon.

“Llamas could be our saviours.”  

But it’s not all doom and gloom. Large scale chemical warfare has been banned since 1925 and biological warfare since 1972. Deadly toxins can be used to heal as well as kill. Ricin and alkylating agents are used in the fight against cancer. Botulinum is used to cure patients of uncontrollable muscle spasms. And if all else fails, llamas could be our saviours.

Llamas (as well as camels and sharks) have incredibly strong, resilient antibodies. Scientists are aiming to develop a whole range of sensors from these antibodies to detect the first signs of biological warfare. Medical treatments for hardy and resistant diseases are becoming better and better all the time. If we are faced with a biochemical threat in the future, we should be better equipped to fight against it.

Humans are great at coming up with newer and more inventive ways of killing each other. Hopefully, one day in the future, chemical and biological warfare shall be relics of a distant, more primitive past.