Biological, Chemical Threat Is Termed Tricky, Complex
Smallpox Virus Is Most Feared in Array of Deadly Weapons

By David Brown
Washington Post Staff Writer
Sunday, September 30, 2001; Page A12

As weapons of terror, anthrax spores would be the easiest to handle. The smallpox virus would be the least accessible, but the most feared. Ounce for ounce, botulinum toxin is the deadliest. Chemical nerve agents, however, are the only ones that have ever actually killed people.

Experts on the subject cannot say with any confidence what the United States should expect if terrorists turn to chemical or biological weapons as their next instruments of attack. Among the germs, toxins and compounds commonly mentioned, there's no clear front-runner.

Each agent offers a complicated mix of accessibility, difficulty of production and delivery, and lethality. A terrorist's goal -- mass death or merely mass panic -- is also a crucial variable that is hard to predict.

"I think it's just guesswork. . . . It's not ignorable is the most that one can say," said Alan P. Zelicoff, a physician and biological weapons expert at Sandia National Laboratories in New Mexico.

Chemical weapons -- in particular nerve agents -- could cause mass death if distributed by airplane in particular settings, such as over a sports stadium. However, it would be hard for a terrorist group to make or acquire the amount of chemicals necessary for an attack of that size.

Much smaller quantities of biological agents -- either microbe or toxin -- are needed to kill large numbers of people. But while it might be feasible for terrorists to get or produce those materials, delivering them is extremely difficult. It requires expertise, special equipment and practice -- all of which is hard to conceal. (The smallpox virus is an exception to this generality.)

For a chemical or biological attack with mass casualties, "you have to have a state or the equivalent," said C.J. Peters, a medical virologist at the University of Texas at Galveston and former head of the special pathogens branch of the Centers for Disease Control and Prevention (CDC).

"I don't think the garden-variety terrorist is going to do anything," Peters said. "But take some group that has a lot of money and put them in a country that's full of terrorists and it's another matter."

However, evidence that it is possible to amass the material and know-how without a government's assistance exists in the case of Aum Shinrikyo, an apocalyptic cult that conducted several acts of terror in Japan in the 1990s.

Aum Shinrikyo, which had about 40,000 members worldwide, operated a three-story chemical factory in Japan. Over a two-year period, it produced 65 pounds of sarin, a liquid nerve agent compounded from several dangerous and highly corrosive starting materials. The poison was then tested on sheep on a ranch in western Australia. The cult also produced some amounts of botulinum toxin and the bacterium that causes anthrax.

Aum Shinrikyo's experience, however, demonstrates that access to the raw materials does not ensure successful attacks. From 1990 to 1993, cult members released the botulinum toxin five times and anthrax spores four times, causing no casualties. The organization's most notorious terrorist act -- the release of sarin in the Tokyo subway on March 20, 1995 -- killed only 12 people, although it injured more than 1,000 and caused panic.

"I'm skeptical of high-tech scenarios for chemical or biological attack," said Jonathan B. Tucker, an expert on chemical and biological terrorism in the Washington office of the California-based Monterey Institute. An act of industrial sabotage at a chemical plant or the contamination of food in a few places is more likely, he said.

The only modern example of biological terror in the United States occurred in 1984 when a religious group called the Rajneeshees put salmonella bacteria in salad bars and coffee creamers in 10 restaurants in Oregon. This caused 751 cases of illness but no deaths.

There's universal agreement that the smallpox virus is the single most dangerous raw material for a non-nuclear terror attack. "If you look at all the bioterrorist agents, you can break them down into smallpox and everything else," Peters said.

Smallpox spreads easily from person to person and can kill up to a third of those infected; and virtually everyone on Earth is vulnerable. It is the only eradicated human infection. The last case occurred in 1978, and routine immunization has not been done for more than two decades. People who got single vaccinations as children are unlikely to still have immunity. There is no good treatment for it, and not enough vaccine exists to immunize large populations.

Starting next week, the World Health Organization will review at least two models of a hypothetical smallpox release to determine how many doses of vaccine might be needed to contain an outbreak, said David L. Heymann, director of communicable diseases at WHO headquarters in Geneva. He said he has heard that several countries are interested in acquiring stocks or restarting vaccine production.

(The U.S. government has 15.4 million doses of smallpox vaccine and has ordered 40 million more for delivery by the end of 2004. The Department of Health and Human Services will try to speed up production and delivery, an official said last week.)

The smallpox virus is known to exist in only two places: freezers at the CDC in Atlanta and at a facility in Koltsovo, Russia. Whether any person, institution or country violated WHO's call in the early 1980s to destroy or transfer samples to those two repositories is unknown.

Many experts believe there is a chance a small number of countries -- including Russia, China, North Korea, Iraq and Syria -- retain samples of the smallpox virus. As recently as 1990, the Soviet Union produced it in large quantities as part of a bioweapons program in violation of the Biological Weapons Convention that the country had signed in 1972.

Among more accessible microbes, the anthrax bacterium "would be the most likely" to be used as a biological weapon, said Kenneth W. Bernard, a U.S. Public Health Service physician who was previously on the National Security Council staff and who is now an adviser to Sen. Bill Frist (R-Tenn.)

"It's a relatively stable bacterium, you can find it in the wild and it has been weaponised by a large number of countries, so the technology for doing so is out there," he said.

Primarily a disease of livestock, anthrax can cause fatal illness in human beings, especially when the causative microbe, Bacillus anthracis, is inhaled. Its advantage as a weapon, besides that, is that unlike most bacteria, B. anthracis can turn into a "spore" form in which it is relatively resistant to stresses such as heat and dryness. This means it can be stockpiled and disseminated dry. Growing large quantities of the anthrax microbe is tricky. Nevertheless, both the United States and Russia made anthrax-based weapons during the Cold War.

Untreated, inhaled anthrax microbes are fatal about 80 percent of the time. The infection can be treated with antibiotics, although they are of little benefit once severe symptoms appear.

Other bacteria frequently mentioned as possible weapons are the ones responsible for plague(Yersinia pestis) and tularemia(Franciscella tularensis). Each infects wild animals, and could be obtained from them.

Pneumonic plague, in which the bacteria infects the lungs, is almost always fatal if untreated. Antibiotic therapy can cure it if started early, but once symptoms appear many people with pneumonic plague die even with antibiotics. There is no vaccine available in the United States.

Tularemia of the lungs is fatal about 50 percent of the time. Antibiotics can help.

Botulinum toxin, produced by the soil bacterium Clostridium botulinum, is often called the most toxic substance on Earth. "A single gram . . . evenly dispersed and inhaled would kill more than 1 million people," according to an article published in February in the Journal of the American Medical Association.

Making large quantities of the toxin requires an industrial operation, such as the one Iraq had before the Persian Gulf War, which allowed it to make about 5,000 gallons of concentrated material. Antitoxins exist but are in short supply. Intensive care, including the use of mechanical ventilators, can save some severely poisoned victims.

To produce mass casualties, airborne delivery would be the preferred method for unleashing all types of chemical or biological weapons. The poisoning of water supplies is unlikely, experts say, because the amount of toxic agent required would be prohibitively large.

Airborne delivery, however, is fraught with problems. There's an optimal size for particles to be inhaled into the lungs. Many terrorism experts are reluctant to discuss this topic, although details are readily available from many sources. In general, producing aerosols of the right size, either of liquids or powders, is extremely difficult or impossible without special equipment and expertise. Crop dusting sprayers, for instance, are designed to produce droplets many times larger than ideal. Weather conditions can also make a huge difference.

Efficiency, though, may be low on a terrorist's list of concerns. That fact alone raises the chance that some group may eventually attempt an act of terror using biological or chemical means.

"The chance of a large [bioweapons] attack that affects tens of thousands or hundreds of thousands is very small," said Zelicoff of Sandia. "But is that what the terrorist cares about? Inducing enough disease to produce panic or disrupt life is probably enough. I would posit that one or two cases of pulmonary anthrax in downtown Washington or New York would achieve that goal."

Staff writer Ceci Connolly contributed to this report.