The most successful of the bio-terrorists was the Aum Shinri Kyo, which made 20 attacks between April 1990 and July 1995. Half the attacks were with biological weapons (Botulinum toxin and Anthrax), but these only killed eight people. Most of the rest of the attacks used VX and Sarin nerve gas. Most of these attacks caused only a handful of injuries. But one Sarin attack, with gas released in five subway cars, killed twelve people and sent over 5,000 to the hospital (but only a fifth of these had noticeable nerve gas injuries.)
The Aum Shinri Kyo members included many skilled engineers and scientists, graduates of Japans best universities. Aum Shinri Kyo also had plenty of money (over $300 million). Recognizing the shortcomings of their biological and chemical weapons, Aum Shinri Kyo was getting into molecular engineering when the organization was broken up by the police in 1996. Had Aum Shinri Kyo been able to keep at it for a few more years, they might have been able to develop far more deadly designer bugs that, so far, have only been produced in American and Russian military labs.
Many other terrorist organizations have tried to develop and use biological weapons. During World War I, a pro-German doctor in Washington created a supply of Anthrax and Glanders. He then used pro-German dock workers to use these two agents to infect animals being shipped to Europe for the war against Germany. This effort was not terribly successful, but it did have an effect and shows how one man, with the proper knowledge and resources, can create and employ biological weapons.
But there is a major problem, biological weapons are difficult to distribute. Yes, it's true that you can hold a quart bottle that could contain enough of some toxin to kill millions. But that's only if you can deliver to each of these people the minute amount of toxin that will kill them. This has proved to be more complex and intractable a problem than terrorists or government scientists initially realized. Moreover, the bio agents tend to be greatly weakened (or destroyed) by exposure to sun, wind or moisture. In other words, you need some very specific weather conditions for a biological weapon to spread, and the conditions you need are rare, or subject to change unexpectedly. This is what the Aum Shinri Kyo kept running into during their many unsuccessful biological weapons attacks. Even releasing bio weapons inside a buildings air conditioning system can run afoul of air filters and the like.
Chemical weapons are not as tricky to handle as biologicals, but that's because chemical weapons were designed to be weapons. Unfortunately (for the terrorists, anyway), chemical weapons are not all that lethal either. During the first major use of chemical weapons (1915-1918), it was found that conventional shells (with explosives inside them) killed more troops than chemical shells (with chemical weapons inside them.) Yes, it's true, during World War I, you were safer if you were shelled with chemical shells than with explosive ones. So why use chemical weapons? Because they terrorize. Troops that would stay and fight when hit with explosive shells, would run away under chemical shell fire. It was for that reason that the generals did not protest too vigorously when, shortly after World War I, it was proposed that chemical weapons be outlawed. Naturally, chemical weapons have been a favorite with terrorists for the last eighty years. Fortunately, eighty years of terrorist effort has not produced any consistently effective way to make and use chemical weapons. One of the major problems with chemical weapons, aside from distribution, is that you need a lot more of the stuff (compared to biological weapons) to do the deed.
Perhaps the most discouraging aspect of terrorist use of biological and chemical weapons is that your attacks are often ignored. This was the Aum Shinri Kyo experience, where many of there carefully prepared and carried out attacks were ignored, even when they caused some injuries. Locals would comment "must have been something in the air," or, "it's the weather" in the wake of the attacks. Not the stuff to be picked up by the media, even if one or two bodies were hauled away. This is the ultimate disappointment for a terrorist, not to be noticed by the media.
Aware of this problem, terrorists have been looking for solutions. The most obvious one is to obtain military grade biological and chemical weapons. Easier said than done, as little of this stuff is made any more and existing stocks are being destroyed. Moreover, most of the terrorists looking for this material are Islamic radicals who have vowed to destroy the nations that made and still possess a lot of it. This makes it very difficult for terrorists to bribe Russian or American officials to part with any of these weapons or the technology to make them. Faced with this, terrorists are trying to duplicate the government technology that has produced more lethal (and easier to distribute) biological and chemical weapons. Aum Shinri Kyo was trying to do this (by obtaining the expensive lab equipment needed) when the group was broken up in 1996. Only five years later, we have new technologies using genetic engineering that can produce even more lethal biological or chemical weapons. Moreover, the technology for genetic engineering (which promises cures for cancer and many other afflictions) is getting cheaper and easier to use. So there is a future out there that is rapidly approaching. And this future features terrorists working in labs, not furtively planting explosives or hijacking aircraft.
Poisonous Potions- Chemical and biological weapons have long been seen as the most likely mass murder weapon for terrorists. But, as we have seen, conventional explosives and 200 ton airliners used as cruise missiles have been far more deadly. But the chemical and biological threat is still out there. As is the possibility of a nuclear weapon. How dangerous is this stuff? In theory, its very deadly. In practice, terrorists have a dismal record in this department.