the gulf war, the threat of Iraqi chemical and biological
weapons felt very real, because it was known that Iraq had
done extensive research on these weapons. In the wake of the
September 11 terrorist attacks, the threat feels very real
again. A chemical or biological weapon used in a large city
would kill thousands of people.
In this edition of HowStuffWorks,
you will learn how chemical and biological weapons really
work, how they might be deployed and what the actual threats
There is an
interesting paradox when it comes to war in the modern world.
Anyone who has experienced war knows that it is about death
and destruction on a massive scale. People die one at a time
because of bullets, bayonets, hand grenades and landmines,
and they die in large groups because of cannons, bombs
Buildings, factories or entire cities get destroyed.
Despite the appearance of anarchy, warfare between modern
nations does have rules. These rules, for example, tend to
discourage the wholesale destruction of civilians, and
they govern the treatment of prisoners of war. The
rules are not always followed to the letter, and many times
are broken completely, but they do exist.
Chemical weapons were first
used in World War I, and the nations of the world quickly
and uniformly decided that these weapons went too far.
Apparently, killing people with flying metal and explosives
was one thing, but launching a cloud of deadly chemicals --
the effects of which could neither be predicted nor controlled
-- was another. Significant treaties
prohibiting biological and chemical weapons, starting as early
as the 1925
Protocol for the Prohibition of the Use in War of
Asphyxiating, Poisonous or Other Gases, and of Bacteriological
Methods of Warfare, have been signed by most nations of
The unfortunate problem is that terrorists, and rogue
nations like Iraq, don't pay attention to significant
international treaties. That is where the threat of chemical
and biological weapons used in random attacks on innocent
civilian populations comes from.
The Basics of Chemical and Biological
Like a nuclear
bomb, a chemical or biological weapon is a weapon of
mass destruction. An effective attack using a chemical or
biological agent can easily kill thousands of people.
chemical weapon is any weapon that uses a manufactured
chemical to kill people. The first chemical weapon used
effectively in battle was chlorine gas, which burns and
destroys lung tissue.
Chlorine is not an exotic chemical. Most municipal water
systems use it today to kill bacteria. It is easy to
manufacture from common table salt. In World War I, the German
army released tons of the gas to create a cloud that the wind
carried toward the enemy.
Modern chemical weapons tend to focus on agents with much
greater killing power, meaning that it takes a lot less of the
chemical to kill the same number of people. Many of them use
the sorts of chemicals found in insecticides.
When you spray your lawn or garden with a chemical to control
aphids, you are, in essence, waging a chemical war on aphids.
Many of us tend to imagine a chemical weapon as a bomb or
missile that releases highly toxic chemicals over a city. (For
example, the movie "The
Rock" featured a scenario in which terrorists tried to
launch a missile loaded with the chemical VX, a nerve
toxin.) But in 1995, the group Aum Shinrikyo released
gas, a neurotoxin, in the Tokyo subway. Thousands were
wounded and 12 people were killed. No giant bombs or missiles
were involved -- the terrorists used small exploding
cannisters to release the gas in the subway.
biological weapon uses a bacteria or virus, or
in some cases toxins that come directly from bacteria, to kill
people. If you were to dump a load of manure or human waste
into a town's well, that would be a simple form or biological
warfare -- human and animal manure contain bacteria that are
deadly in a variety of ways. In the 19th century, American
Indians were infected with smallpox through donated blankets.
A modern biological weapon would use a strain of bacteria
or a virus
that would kill thousands of people. Tom Clancy has explored
the idea of biological terrorism in two books: "Executive
Orders" and "Rainbow
Six." In both books, the source of infection is the Ebola
virus. In these plot lines, the infection is spread through
small aerosol cans (like those used by insecticide products to
create "bug bombs") released at conventions, or through
misting systems used to cool sports venues.
Feared Chemical Agents
An effective chemical
attack would use chemicals that are extremely toxic to people
in small quantities. The most commonly feared agents include:
- Sarin - Sarin is a nerve agent. This means that,
once inside your body, it affects the signaling mechanism
that nerve cells use to communicate with one another.
Sarin is a cholinesterase inhibitor -- it gums up the
which your nerve cells use to clear themselves of
acetylcholine. When a nerve cell needs to send a message to
another nerve cell (for example, to cause a muscle to
contract), it sends the message with the acetylcholine.
Without cholinesterase to clear the acetylcholine, muscles
start to contract uncontrollably, which eventually causes
death by suffocation (since the diaphragm is a muscle).
Sarin is probably the most feared chemical agent because
it has actually been used by terrorists to kill people. In
1995, the group Aum Shinrikyo released sarin
gas in the Tokyo subway, wounding thousands and killing
12 people. It is not particularly difficult to manufacture,
and about 1 milligram in the lungs will kill a person.
- VX - VX is very similar to Sarin. It works in the
same way, but is more toxic. One milligram on the skin will
kill a person. See this
page for more information.
- Mustard Gas - Mustard gas has been around since
World War I. It blisters the skin and destroys lung tissue.
About 10 milligrams in the lungs will kill a person.
- Lewisite - Lewisite, like mustard gas, is a
blistering agent, and has also been around since World War
One of the problems with these chemical agents is that
there is no easy way to protect yourself. On the battlefield,
soldiers wear gas masks and complete skin covering when
chemical or biological attack is deemed possible. If a city
were to experience a large-scale VX attack, people would have
to be wearing a waterproof and airtight suit and a gas mask at
the time of the attack in order to be protected.
Feared Biological Agents
There are many ways
to implement a biological attack, but these are some of the
most feared agents:
It would also be possible to cause significant
problems by targeting the food supply. For example, foot-and-mouth
disease has recently been a huge problem in Europe.
Spreading the disease to the United States would be relatively
easy and very disruptive.
- Anthrax - Anthrax
is a bacteria,
but it has a spore form that is very durable. If the spores
or bacteria get into your lungs, they reproduce and create a
toxin that can be fatal. See How Anthrax
Works for more information.
- Smallpox - Smallpox is a virus.
It was a major killer until it was controlled with
vaccinations in the 20th century. It has been eradicated
world-wide, but the fear is that terrorists could release
The main problem with smallpox, unlike with anthrax, is
that it is highly contagious. It spreads and kills
very quickly. Up to 40 percent of people who catch the virus
die from it in about two weeks, and there is no good
treatment for the disease. Vaccinations are the main
protection, but they must be given prior to infection in
order to work. This
page has extensive information.
- Botulin toxin - Botulin bacteria produce the
botulin toxin, and this toxin is deadly to people in
incredibly small quantities (as little as a billionth of a
gram). The toxin inhibits
the release of the chemicals in nerve cells that cause
muscle contractions, so it causes paralysis.
- Ebola virus - The Ebola
virus was popularized as a biological warfare agent by
two books written by Tom Clancy. The virus takes about a
week to kill the victim, and spreads through direct contact.
The previous sections listed
eight of the most-feared chemical and biological agents. There
are dozens of others that are less well known, either because
they are not as toxic or not as easy to spread.
There are three ways to spread a chemical or biological
agent so that it would infect a large number of people:
The most-feared scenario
is through the air. Here are the techniques most commonly
- Through the air
- Through a municipal water supply
- Through the food supply
To learn more about toxic agents, how they're spread
and methods the military uses to protect soldiers against
them, check out the links on the next page.
- A bomb or a missile explodes, spreading the chemical or
biological agent over a wide area.
- A crop-duster or other aircraft sprays the agent over a
- A car or truck drives through the city spraying a fine
mist along city streets in crowded areas.
- Small bombs or aerosol canisters are released in crowded
areas like subways, sports arenas or convention centers.
Lots More Information
Other Informative Links