How Biological and Chemical Warfare Works

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 and missiles. Buildings, factories or entire cities get destroyed.

Despite the appearance of anarchy, warfare between modern nations does have rules. These rules, like the Geneva Conventions, 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 or bacteria -- 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 world.

The unfortunate problem is that terrorists and rogue leaders don't pay attention to significant international treaties.

Charles Taylor, the former president of Liberia, is one such rogue leader. Among many crimes, he is on trial for violating the Geneva Conventions during the Liberian civil war. The charges include having soldiers kill peacekeepers and rape and murder civilians [source: Crane].

Signatories have also ignored the Biological Weapons Convention. The Soviet Union signed the treaty, then secretly built a massive arsenal of biological weapons [source: New York Times].

The Chemical Weapons Conventions have been disregarded as well. Although Iraq was a signatory, Saddam Hussein rained mustard gas and sarin on Kurdish civilians in Iraq, killing thousands, during the Iran-Iraq war [sources: Burns, Chivers].

And states that don't sign the treaties, like North Korea, posses whatever they like. North Korea has sarin and anthrax weapons and is suspected of being armed with smallpox [source: Kristof].

That is where the threat of chemical and biological weapons used in random attacks on innocent civilian populations comes from.

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 Weapons

A 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 sarin gas, a nerve gas, in the Tokyo subway. Thousands were wounded and 12 people were killed. No giant bombs or missiles were involved -- the terrorists used small exploding canisters to release the gas in the subway.

Although the attack wasn't intentional, Blackwater Worldwide, contracted by the U.S. to protect officials in Iraq, accidentally dropped canisters of CS, a gas similar to tear gas, on soldiers and civilians at a checkpoint to clear the road for a convoy in 2005 [source: Risen].

Biological Weapons

A 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 of 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.

An effective chemical attack would use chemicals that are extremely toxic to people in small quantities. From least to most threatening, the most commonly feared agents are:

Not all feared chemical weapons attack the nerves. Blistering agents, like mustard gas, blister the skin, destroy lung tissue and can kill people. But they are less deadly than nerve agents.

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 coverings 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.

There are many ways to implement a biological attack, but these are some of the most feared agents, from least to most threatening:

It would also be possible to cause significant problems by targeting the food supply. For example, foot-and-mouth disease has been a huge problem in Europe. Spreading the disease to the United States would be relatively easy and very disruptive.

The previous sections listed 11 of the most-feared chemical and biological agents. There are dozens of others that aren't as 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 discussed:

Here are some ways the U.S. is protecting civilians against attacks:

Chemical and biological weapons are huge, ever-changing subjects. To learn more about them, follow the links on the next page.