Now that terrorists have demonstrated they're capable of carrying out unthinkable attacks of extreme devastation, some believe the United States should be on higher alert for a biological or chemical attack, or an assault on a nuclear facility.
ABCNEWS.com talked to several experts to learn about these weapons, the preparedness of the United States for such attacks and possible defenses against them, including:
Kyle Olson of Community Research Associates, an Alexandria, Va., consulting firm that specializes on domestic preparedness and terrorism Michael Allswede of the Department of Emergency Medicine at the University of Pittsburgh Kathleen Vogel of Cornell University Victor Weedn of Carnegie Mellon University Thomas Inglesby and Tara O'Toole of the Center for Civilian Biodefense Studies at Johns Hopkins University
Most agree that while a biological or chemical attack could be devastating in theory, the logistical challenges of developing effective agents and then dispersing them make it less likely a terrorist could carry out a successful widespread assault.
Here are some questions and answers on these issues:
Would a chemical or biological attack be more deadly? Questions on biological warfare Questions on chemical warfare Threat to Nuclear Power Plants Threat to Water Supply
Q: Would a chemical or biological attack be more deadly?
A: If cultured well, a biological weapon would have a more devastating impact since people infected with a biological agent can spread the disease for months and over a broad geographical region. One person infected with smallpox, for example, could pass along the disease to 20 or more individuals. In this way the disease could spread broadly and rapidly. A chemical weapon would only affect people who are near the place of its release and the chemical would dissipate with time.
Q: How easy would it be for a terrorist to launch a biological attack?
A: Experts say it remains very difficult to transform a deadly virus or bacterium into a weapon that can be effectively dispersed. A bomb carrying a biological agent could likely destroy the germ as it explodes. Dispersing the agents with aerosols is challenging because biomaterials are often wet and can clog sprayers. The Aum Shinrikyo cult, which released the nerve gas sarin in the Tokyo subway system in 1995, killing 12 people, repeatedly tried to produce and disseminate agents, including anthrax, but failed each time.
Some experts think suicide terrorists could resort to spreading smallpox by infecting themselves and then wandering and breathing among large groups of people. But in that scenario, large numbers of people still might not be affected since infection rates vary among people and because people infected by the virus are highly infectious only seven to 10 days following the outbreak of a rash.
Q: What biological weapons pose the biggest threat?
A: Right now, scientists are most concerned about smallpox and anthrax. Both are bacteria that can spread through the air in a powder and cause swift, deadly diseases. Smallpox could be even more lethal because it's easily spread from one person to another. Also worrisome are the bubonic plague, botulism, tularemia and ebola.
Q: How easy is it to develop a biological weapon?
A: Developing an effective anthrax strain is challenging since the spores have to be crafted to just the right size. If too small, a person will exhale the spores. If too large, the spores fall to the ground and become, as Olson says, "road kill." Developing a smallpox agent is also difficult because the virus cannot be easily grown as a seed culture and it is so deadly that lab workers trying to culture the virus could easily become infected and die.
Q: Is the United States prepared for a biological attack?
A: Most experts say the United States is not adequately prepared. The Department of Defense has started vaccinating some members of the military against anthrax, but there are no such vaccination supplies for the general population. The Center for Disease Control has enough stockpiles of smallpox vaccines to medicate 12-15 million people and has contracted for 40 million more doses. There is a vaccine against the bubonic plague but it needs to be administered during a four- to seven-month period before exposure.
There is some concern that the smallpox vaccine may not be effective because it is about 40 years old and has likely degraded over time. This may also be true for people who received a smallpox vaccine in their youth. There is also the danger that terrorists could develop new strains of smallpox and anthrax. The time required to develop and establish a new vaccine is estimated to be about 36 months.
Rapid detection of a disease outbreak also remains a problem since many doctors have not been trained in how to recognize early symptoms of scourges like anthrax and smallpox. Early symptoms of anthrax can appear as a simple flu. The early signs of smallpox become more obvious about three days following exposure when lesions begin appearing. Some argue that emergency medical facilities are insufficient to handle a widespread attack.
Q: Is there any plan to develop new vaccines?
A: BioPort Corp. of Lansing, Mich., plans to file papers to ship new Anthrax vaccines next year, but the drug, as planned, would not be safe for children, pregnant women or the elderly.
The U.S. government is said to have a stockpile of 12 million to 15 million doses of smallpox vaccine, and is exploring ways to extend supply through diluting individual doses or buying vaccine from other countries, Dr. Luciana Borio, a fellow at Johns Hopkins University Center for Civilian Biodefense Studies, told the Reuters news service. The U.S. government has awarded British biotechnology firm Acambis Plc a $343 million contract to begin testing a new smallpox vaccine that meets modern safety standards. Acambis executives say the company could begin clinical trials for the vaccine early next year, and deliver it for full-scale production by 2004.
The CDC plan is to have 40 million doses on reserve in case of an outbreak. The vaccine can be given after people are exposed and still be effective. Because there could be severe side effects from this type of vaccine, so come doctors are skeptical of the need to dole it out unless there is an outbreak.
Q: Which diseases that could be used as weapons exist now?
A: Smallpox was eradicated in 1979 and the only known samples of the virus exist under top security in the United States and Russia. Scientists estimate that during a big year, there are about 10,000 cases of anthrax worldwide, almost all resulting from people eating contaminated cattle. There have been no known cases of anthrax in the United States. About 110 cases of botulism are reported in the United States each year.
Q: Once infected, how easy is it to treat the diseases? A: Doctors can prescribe antibiotics against anthrax that can work if initiated early. If left untreated, the disease is fatal in 90 percent of cases. So far there is no known antiviral substance that has proven effective against smallpox after exposure. Past data suggest the disease is fatal in 30 percent or more of cases.
Q: What countries or terrorist groups are developing these biological weapons?
A: The United States and the former Soviet Union had biological weaponry programs in place for decades and both have stockpiles of deadly germs. Although a global treaty in 1972 bans such weapons, scientists in both countries continue to research biological weapons to better understand the agents for defense purposes.
Iraq admitted to the United Nations in 1995 that it had loaded anthrax spores into warheads during the Gulf War. Osama bin Laden has expressed interest in deadly germs and recent reports say satellite photos have revealed dead animals at a terrorist training camp in eastern Afganistan operated by bin Laden. Some speculate the animals were killed by a chemical or biological agent.
Q: Have biological weapons been used before?
A: Assyrians would catapult animal decaying carcasses over the walls of besieged cities. Soldiers under the Roman Empire tossed animal corpses into their enemies' water supplies. In the 18th century, British soldiers deliberately distributed smallpox-infected blankets to Native Americans.
More recently, the only known successful use of biological weapons in the United States was by the Bhagwan Shree Rajneesh cult in 1984. The group contaminated salad bars in 10 restaurants in The Dalles, Ore., with Salmonella Typhimurium, causing several hundred people to become ill.
Q: What chemical weapons pose the biggest threat?
A: Sarin, a chemical nerve agent developed by Nazi Germany during the 1930s, poses a large threat because it is fairly easy to manufacture. A thimble-sized portion of a nerve toxin like sarin or tabun (also developed by Nazi Germany) can kill a person in minutes; a few particles can produce death in 24 hours. There is also concern that terrorists might use ricin, a natural toxin derived from the castor bean. And terrorists could adapt common industrial chemicals such as chlorine and hydrogen chloride to be used as chemical weapons.
Q: Have groups or countries launched chemical attacks?
A. Chemical agents have been used on the battlefield since at least World War I. During the Gulf War, Saddam Hussein was accused of using chemical weapons against Iraq's Kurdish minority. A Japanese cult released sarin in the Tokyo subway station in 1995, killing 12 people and injuring more than 5,000. Some reports indicate that Osama bin Laden has told his biographer that he is prepared to launch a strike using chemical weapons.
Q: How easy would it be for a terrorist to launch a chemical attack?
A: Because they're relatively easy and inexpensive to manufacture, chemical weapons have long been considered "the poor man's atomic bomb." One group of experts has estimated the cost of killing people using chemical weapons would be about $600 per square kilometer, compared with $2,000 per square kilometer using conventional weapons. Chemical weapons could be dispersed from a crop dusting plane, from aerosols, or by distributing the chemical in water supplies.
Q: Is the United States prepared for a chemical attack?
A: Most experts believe the United States is adequately prepared for a chemical attack since such attacks can usually only target a limited area. Appropriate gas masks can protect a person from breathing in a deadly chemical and protective clothing can prevent exposure through the skin.
Threat to Nuclear Power Plants
Experts say it is unlikely that a terrorist attack on a nuclear power station could cause mass casualties. The containment domes that enclose nuclear reactors are made of steel and concrete several feet thick, and are designed to withstand the impact of a large plane — although not as large as a Boeing 757 or 767. However, experts say it is virtually impossible that an attack could cause a nuclear explosion.
An attack could cause a radiation leak, but the leak would be contained within a relatively small area, with time to evacuate nearby residents.
Another fear is that terrorists could storm a nuclear plant and gain control of the station. The Nuclear Regulatory Commission has conducted 68 mock terrorist assaults since 1991, and in nearly half of the cases the assault teams managed to simulate damage to the nuclear core. However, experts note that these teams are highly trained, and that nuclear plants have boosted security since the Sept. 11 attacks.
If a terrorist team did gain access to the control room, they would need specialized training to do major damage, as well as familiarity with the workings of the particular station.
Threat to Water Supply
Although the water supply might appear to be an effective way of distributing chemical or biological weapons, experts say it is much harder than is portrayed in movies. Even with highly concentrated poisons, attackers would need to dump several truckloads into the water system to do any harm — a remote possibility considering the increased security at reservoirs and pumping stations.
Biological threats are also dispersed by dilution. Anthrax, for instance, requires thousands of spores to infect a person, meaning that it would be little danger when diluted.
— ABCNEWS' Amanda Onion, Jeffrey Carpenter and Andrew Giese contributed to this report.