What Does it Mean to Weaponize a Biological Agent

What Factors are Considered When a BW is Weaponized?

When biological agents are made into or used as a weapon or as a potential weapon they are being weaponized. How a biological agent is weaponized depends on what the state/nonstate actor wants to accomplish. Several questions have to be answered. How many people will be targeted? Where is the attack going to take place? Is this attack meant to incite fear in the population at large or to take over a particular region? Is this BW going to be used as a WMD or for assassination? 

There are several ways in which a biological agent can be released. They can be sprayed into the air as a wet or dry aerosol, placed wet or dry in food or water sources and injected into people, plants or animals; or released by explosive dissemination. The means of release are in part dependent on the BW used and the number of victims the attacker wants to infect. 

BW released into the air using aerosols have the potential to infect many people in highly populated areas. Release into water and food sources can also infect large numbers of people. Injection of a BW usually targets just a few people at time. Aerosols, water, and food contamination can make it difficult for an attacker when they want to occupy the area of the BW release since they are likely to also become infected. This is especially the case if the BW lasts long periods of time in the environment. However, if the attacker does not want to occupy the area of the BW release then the use of aerosols and contaminating water sources may obtain the objectives of causing disease and fear while at the same time drain the enemy’s resources as they attempt to decontaminate the area. 

Some BW are more effective if injected into the blood stream or muscles. Some means of injecting the BW would have to be employed to infect a target. It is more difficult to infect large numbers of people using injections. It also usually requires the attacker to be in closer proximity to the victims and the chances of getting caught increase. In one of the most famous historical examples, a poison dart filled with ricin and fired from an umbrella in London in 1978 killed a Bulgarian dissident Georgi Markov (54). 

Some BW infect a people following ingestion. A strain of Salmonella was used by the Rajneesh cult in Oregon to infect others at a local restaurant. The Rajneeshees grew the organism in a nutrient rich liquid media and placed it on food items on the salad bars. In this case relatively little had to be done to prepare the BW other than grow it up and sprinkle it on the food (5). 

Other BW are most effective if inhaled. Typically, aerosols can be released by two basic means: point or line source dissemination. Point source dissemination involves the use of stationary aerosol generators or bomblets. Line source dissemination involves release of the BW from low-flying aircraft or speedboats along the coast. This allows the attacker to be remote from the site of the attack making it less likely that they would be caught in the act. 

Aerosol release is more dangerous in that the aerosols if released prematurely can also infect the attackers (Boomerang Effect; 30). Even though aerosols can infect many more people there is a lot more involved in weaponizing such BW. It usually requires concentration of the BW and then generation of the right particle size so that it will float in the air and yet be able to settle in the lungs once it is inhaled. 

Aerosols can be either wet or dry and are made up of small particles. Dry aerosols tend to travel further than wet aerosols. The larger the particles in the aerosol the more rapidly it will settle to the ground making it less effective.  Particles larger than 5 micrometers (the diameter of a human hair can be from 17-181 micrometers) do not go down into the lungs but are caught up in the mucus that lines the nose and the back of the throat. The particles are then swallowed and the acid in the stomach kills most of the organisms. If the particles were too small they would be inhaled into and exhaled from the lungs before they can settle down on the inner surfaces of the lungs. 

An effective aerosol must have particle sizes between 0.5 and 5 micrometers. These aerosols are invisible, do not have any odor, and can remain in the air for long periods of time depending on the weather conditions. 

If the aerosol is dry then the organisms must first be concentrated and dried. After drying they must be gently ground up to the correct particle size. If the grinding is too rough it will kill the organisms. When particles are at the size to settle on the inner surfaces of the lungs electrostatic charges cause the particles to clump together. As a result, additives must be included to eliminate the clumping of the particles. The particle sizes in wet aerosols are determined in part by the size of the nozzle used to deliver the aerosol and by certain additives placed with the BW before release. In summary a lot of technology and engineering is needed to deliver these aerosols making it nearly impossible for an untrained person to release an effective aerosol (8, 20).


© 2005 Neal Chamberlain. All rights reserved. 
Site Last Revised 5/13/05
Neal Chamberlain, Ph.D. A. T. Still University of Health Sciences/Kirksville College of Osteopathic Medicine.

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