Historical Perspective of the Chemical/Biological Battle Space

CB agents have been considered effective weapons for combat for more than a millennium, from the tossing of plague victims over castle walls to the poisoning of water supplies and individuals. However, lethal CB weapons were first used extensively by the military in World War I (U.S. Army Office of the Surgeon General, 1997). Trench warfare, in which forces were deployed in fixed positions vulnerable to concentrated pockets of lethal fumes, provided fertile ground for the development of chemical weapons that could be dispersed as fogs, mists, or dense vapors. The first chemicals used during World War I were noxious gases (chlorine [Cl₂], hydrogen sulfide [H₂S], and phosgene [COCl₂]) and were released from upwind storage vessels along enemy lines. Local meteorological patterns were used to predict the movement of the gas clouds. However, this methodology was often ineffective because rapid changes could cause deadly clouds to settle on friendly forces, resulting in self-inflicted casualties. Early chemical agents were primarily inhalation threats, and effective gas masks (or respirators) were quickly developed and refined to protect personnel against toxic gases.

Respirators greatly diminished the tactical advantage of using toxic gases, and new chemical warfare agents had to be developed. Some of the new agents were chemical mustard agents, sulfur and nitrogen mustards, which caused serious injury and incapacitation not only when they were inhaled but also when they came into contact with the skin or mucous membranes. Because of the percutaneous threat of these agents, gas masks alone could no longer provide adequate protection, and garments to protect skin had to be developed.

In addition to new agents, new delivery systems were also developed. At first, artillery shells were modified to accommodate agents. Later, more sophisticated techniques evolved. Although there was still some risk that changes in local weather and climate could cause chemical agents to drift onto friendly targets, the risk was mitigated significantly as targeting became more accurate.

During the interval between World War I and World War II, new and more lethal families of chemical agents were developed. German scientists working to provide weapons for their military, discovered and refined a series of ''nerve" agents—tabun (GA), soman (GD), and sarin (GB)—that attacked the central nervous system, could be absorbed through mucous membranes and the skin as well as inhaled, and were lethal in much smaller doses than the chemicals that had been used during World War I. At the same time, Japanese scientists were experimenting with agents of biological origin, such as plague and typhus. These agents were tested on human prisoners (U.S. Army Office of the Surgeon General, 1997).

Although neither chemical nor biological agents were actually used during World War II to achieve any military objectives, work continued and provided the foundation for the extensive CB research program of the Cold War powers. Led by scientists in the United States and the Soviet Union, the CB weapons programs flourished during the 1950s and 1960s. New nerve agents were developed (the family of V agents) that were not only more lethal in smaller inhaled doses but could also be absorbed directly through the skin. Existing agents were refined and mixed with additives to increase their persistence in the environment and the difficulty of decontamination.

During this time, natural toxins produced by biological organisms were also developed as weapons. The poisons produced, for example, by castor beans (ricin), puffer fish (tetrodotoxin), bacteria (botulinum), and fungi (mycotoxins) are among the most toxic compounds known and are lethal in even smaller quantities than V-agents. Although the production of large quantities of these toxins was difficult because of their high degree of lethality, much smaller amounts were required.

In addition to plague and typhus, other biological pathogens were studied as biological warfare agents, and weaponization techniques were researched and developed. Virtually every type of disease, condition, and means of dissemination was studied. From smallpox to cholera, from anthrax to hemorrhagic fevers, from tularemia to parasites, these agents and others were considered as possible weapons. The exposure of troops to pathogens or toxins through food supplies, water supplies, aerosols, and insect or animal vectors was also studied.

During the post-1950s era, the means of dissemination of lethal agents became major research objectives. Airborne spray tanks, specialized artillery shells, CB-capable missile warheads, and an assortment of individual weapons were developed. At the same time, the threat of exposure led to the development of defenses. Protection (both individual and collective) and decontamination became high-priority issues and stimulated the development of protective equipment. Thus, gas masks, protective garments, boots, gloves, protective shelters, and decontaminating solutions and systems were produced.

Even as the development of more and more lethal agents continued, societal fears and the conviction that the use of weapons of mass destruction was unethical resulted in treaties and international agreements that limited the proliferation, control, and testing of CB weapons. The Geneva Protocol of 1925 condemned the use in war of asphyxiating, poisonous, or other gases, as well as bacteriological warfare. The United States signed the Geneva Protocol but did not ratify it until 1975. However, the United States reserved the right not to be bound by the protocol if any enemy or state or any of its allies did not respect the protocol.

In 1972, the Biological and Toxins Weapons Convention (BWC) was signed. Under the terms of the convention, the parties agreed not to develop, produce, stockpile, or acquire biological agents, toxins, weapons, or means of delivery. Many years later, the Chemical Weapons Convention (CWC) banned the acquisition, development, production, transfer, and use of chemical weapons throughout the world. The United States signed the CWC in 1993 but did not ratify it until 1997. On June 25, 1999, the President issued an Executive Order implementing the CWC; it went into effect on June 26, 1999.

Since the implementation of these treaties, both the United States and the former Soviet Union have embarked on programs to destroy residual stockpiles (U.S. Army Office of the Surgeon General, 1997). However, CB technologies have been transferred to, and proliferated in, other countries; and modem bioengineering and molecular biological capabilities have given even small nations and groups the capability of developing novel, lethal agents. Documentation of the use of chemical weapons in localized wars and credible warnings from the intelligence community confirm that many potential enemies in regions to which U.S. forces may be deployed have the capability of using CB weapons.

Thus, the United States could find itself confronted with adversaries who have either chosen not to sign and ratify the CWC and/or BWC or have chosen to ignore them. Nevertheless, as a signatory of both the CWC and BWC, the United States has adopted a national policy of not using biological or chemical weapons in warfare even in retaliation for a CB attack. This asymmetrical threat has led to a national military strategy based on defense and deterrence (Chow et al., 1998; DoD, 1995; Joint Chiefs of Staff, 1995; Secretary of Defense, 1999; U.S. Army and U.S. Marine Corps, 1996). The policy is to deter the use of CB agents by enabling U.S. forces to survive, fight, and win a war under CB conditions. This policy has stimulated a continuing research program for refining military doctrine, for developing protective technologies, and for training U.S. forces against CB attack.

U.S. Response

The Army Chemical Corps has historically been the military organization primarily responsible for dealing with CB threats. Founded in June 1918 as the Chemical Warfare Service and renamed the Army Chemical Corps in August 1946, the Army Chemical Corps has alternately enjoyed support and been threatened with elimination, depending on political and economic exigencies. Prior to 1920, the development of chemical defenses was not tightly structured. Various chemical warfare schools (called gas schools) existed, but no single department was responsible for coordinating chemical warfare activities. The Army assumed the de facto role of executive agent for CB R&D by virtue of its large and long-term investment in the development of chemical equipment and its extensive experience with chemical exposure on the battlefield. The Army controlled the production of chemicals, the development and production of defensive equipment, training, testing, basic research, and a new chemical warfare unit.

Although the Army was more actively involved in this area than other services, in fact each military service was free to develop its own CB defense program and material. Each service had a separate budget and administered the budget and its program independently, cooperating with other services as the needs of basic or developmental research dictated. Each service also prioritized its needs for equipment separately, on the basis of service-specific needs. As operations became more and more integrated and cooperative (joint operations), both Congress and the military departments recognized the need for joint R&D programs and integrated procedures to improve joint operations and decrease logistical support burdens. This need has become more compelling as budgets have become more constrained and the cost of duplication of equipment has become unsupportable.

In the early 1990s, Congress began to encourage joint R&D programs. However, encouragement was not enough to overcome decades of independent activities (Nilo, 1999). Therefore, Congress passed Public Law (PL) 103-160, the National Defense Authorization Act for Fiscal Year 1994 (Title XVII), which included the following stipulations (U.S. Congress, 1994):

• The CB defense program would be coordinated by a single DoD office that would oversee the program through the Defense Acquisition Board process.
• The CB defense program would have a coordinated/integrated budget.
• CB defense funds would be administered from DoD-level accounts.
• The Army would be the executive agent for coordination and integration of the CB defense program.

In order to meet the requirements of PL 103-160, a new structure, the Joint NBC¹ Defense Board, was established to provide oversight and management of DoD's NBC defense program (Figure 2-1). The NBC Defense Board's responsibilities include approval of (1) joint NBC requirements; (2) the Joint NBC Modernization Plan; (3) the consolidated NBC Defense Program Objective Memorandum (POM); (4) the Joint NBC Research, Development, and Acquisition (RDA) Plan; (5) joint training and doctrine initiatives; and (6) the Joint NBC Logistics Support Plan. The Joint NBC Defense Board Secretariat is responsible for management of program and acquisition strategies; planning, programming, budgeting, and execution of the program; and consolidation and integration of CB requirements and programs for all services.

Figure 2-1

Management structure of the DoD Chemical and Biological Defense Program Note: CBD = chemical/biological defense; DARPA = Defense Advanced Research Projects Agency; DATSD (CBD) = Deputy Assistant to the Secretary of Defense for Chemical/Biological Defense; (more...)

Two subordinate groups support the Joint NBC Defense Board: the Joint Service Integration Group (JSIG) and the Joint Service Material Group (JSMG). The JSIG is responsible for joint NBC requirements, priorities, training, and doctrine. Thus, the JSIG develops a prioritized list of needs, requirements, and programs, which are based on commander-in-chief (CINC) priorities, threat projections, and analyses. A list of current, integrated CINC priorities, as well as the NBC Defense Program priorities can be found in Tables 2-1 and 2-2.

Table 2-1

Integrated CINC Priorities.

Table 2-2

Nuclear, Biological, Chemical (NBC) Nonmedical Defense Program Priorities.

The priorities identified by the JSIG are inputs to the JSMG, which is responsible for the coordination, integration, planning, and programming of nonmedical RDA, science and technology, and logistics sustainment. Other responsibilities of the JSMG include preparation of the Joint Service NBC Defense RDA Plan, preparation of the Joint Service NBC Defense Logistics Support Plan, continuous review of the technology base, and reviews of developmental programs for possible NBC defense applications and/or impacts. The JSMG and the JSIG jointly prepare the consolidated NBC Defense POM strategy.

The services receive funding for NBC defense programs from the Office of the Secretary of Defense after having their inputs considered by the NBC Defense Board. Programmatic and other decisions are based on a formal voting process in which each member has one vote. The membership of each group (the NBC Defense Board, the JSIG, and the JSMG) consists of representatives of each of the services, the joint staff, the Defense Logistics Agency, the Joint Program Office for Biological Defense (JPO-BD), the Medical Research Material Command, and the Special Operations Command.

Execution of the RDA program under the JSMG is controlled by a group of five commodity area managers. Each service has been assigned lead responsibility for the commodity area most closely aligned with its expertise: contamination avoidance—Army; individual protection—Marine Corps; collective protection—Navy; decontamination—Air Force; medical protection—Medical Research Material Command. These commodity area managers are responsible for developing material that is usable in the field.

Discussions with personnel at the U.S. Army Chemical School, Soldier and Biological Chemical Command, JSMG, Deputy Chief of Staff for Operations, and outside contractors revealed general dissatisfaction with the prioritization process because service-specific projects were often given priority over projects based on multiservice needs through a process of political compromise and CINC priorities were largely ignored in the process (Blankenbiller, 1998; Nilo, 1999; U.S. Army SBCCOM, 1998). A comparison of CINC priorities (shown in Table 2-1) and program priorities (shown in Table 2-2) lends some credence to these complaints.

Relationships Among Policy; Doctrine; Research, Development and Acquisition; and Threat

The intelligence community provides data, analysis, and advice on the development of CB capabilities of threat nations. Based on information about the types, quantities, and delivery systems of CB agents, CINCs and the JSIG evaluate the ways these agents could be used against U.S. troops. Their evaluation is then used to develop policy, doctrine, training, and equipment to counter the perceived threat. As the threat changes, approaches to countering the threat should also change.

The mission to protect forces from the effects of CB weapons has developed into a five-pronged approach. The thrust of current doctrine is to avoid contamination/exposure and to prevent adverse health effects. Three major elements of this approach (individual protection, collective protection, and decontamination) will be discussed in detail in subsequent sections of this report.²

Characteristics of Current and Future Chemical and Biological Agents

Effects and Tactical Utility of Chemical Agents

Chemical agents can be characterized as either lethal or nonlethal (incapacitating) (see Table 2-3); however, these distinctions have more to do with intent and use than with the composition of the agents because all agents are lethal in high concentrations. There are three classifications of lethal agents: nerve agents, choking agents, and blood agents.

Table 2-3

Categorization of Chemical Agents.

Nerve agents inhibit acetylcholinesterase, an enzyme involved in the transmission of nerve impulses. Inhibition of this enzyme results in continuous stimulation of the nervous system. Nerve agents act more quickly and are more lethal than other chemical agents. They can be absorbed through the skin, the eyes, or the respiratory tract. Symptoms include runny nose, tightness in the chest, impaired vision, pinpointing of the pupils, difficulty in breathing, excessive salivation and drooling, nausea, vomiting, cramps, involuntary twitching, loss of bowel and bladder control, headache, confusion, drowsiness, coma, and eventually death.

Choking agents, which are primarily taken in via the respiratory tract, are strong irritants that attack lung tissues causing membranes to swell and become "leaky." The lung can then fill with fluid, and death can result from pulmonary edema. Acute nonlethal exposures to choking agents can result in chronic lung disease.

Blood agents are primarily absorbed via the respiratory tract. They inhibit the enzyme cytochrome oxidase or combine with hemoglobin to prevent the normal transfer of oxygen from the blood to body tissues. Exposure to these agents causes seizures due to lack of oxygenation.

Agents classified as nonlethal or incapacitating include vesicants, lacrimators, and sternutators. Vesicants, or blister agents, which affect the eyes and lungs and blister the skin, are often lethal if ingested or absorbed through the lungs. Lacrimators cause tearing and irritate the skin and respiratory tract. Sternutators cause coughing, nausea, and vomiting.

An agent's tactical utility is partly determined by its physical properties including: (1) whether the agent is effective in the short or long term (persistence of the agent in the environment); (2) whether the agent can be targeted to a specific area or is affected by wind and weather conditions; (3) whether the agent presents an inhalation or percutaneous threat, or both; (4) whether the agent is stable during dissemination; and (5) other physical and chemical factors.

Agents are often characterized as persistent (lasting longer than 24 hours as a hazard) or nonpersistent (lasting less than 24 hours as a hazard). Ordinarily, persistent agents are disseminated as liquids, and nonpersistent agents are disseminated as gases. However, most agents, through the use of additives, can be made persistent or nonpersistent.

The actual use of CB weapons may not be necessary because the threat of CB weapons may result in troops taking defensive measures. Forces threatened by CB weapons will be burdened by the need to transport protective gear and decontamination equipment, and the effectiveness of fighting units can be diminished if personnel are forced to operate in protective gear. The threat of CB weapons will also increase the psychological burden of personnel.

Effects and Tactical Utility of Biological Agents

Biological agents can be classified into three main groups: pathogenic microorganisms, viruses, and toxins. The first two groups are living, self-replicating organisms; however, viruses only self-replicate in a host. Toxins are poisons (nonliving) produced by bacteria, plants, or fungi. Table 2-4 gives examples for each category of biological warfare agents.

Table 2-4

Categorization of Biological Agents.

Pathogenic microorganisms can be classified as protozoa, fungi, bacteria, and rickettsia. Protozoa are one-celled organisms that are motile. Fungi are organisms that do not use photosynthesis, are capable of anaerobic growth, and draw nutrition from decaying vegetable matter. Most fungi form spores.

Because bacteria are much better understood than other biological agents, they are the most likely type of biological warfare agents (All et al., 1997). Bacteria are small free-living organisms, most of which can be grown on a solid or in a liquid culture. Bacterial structures consist of nuclear material, cytoplasm, and cell membranes. They vary in shape and size from spherical cells and cocci (with a diameter of 0.5 to 1.0 microns) to bacilli (with a diameter of 1.0 to 5.0 microns). In response to changes in their environment, some types of bacteria can change into spores, which are more resistant to cold, heat, drying, chemicals, and radiation, than bacteria themselves. Diseases caused by bacteria often respond to treatment with antibiotics.

Viruses vary in size from 0.02 to 0.2 microns and must be cultivated in living cells in order to multiply. Rickettsiae have characteristics common to both bacteria and viruses. They resemble bacteria in that they possess metabolic enzymes and cell membranes, utilize oxygen, and are susceptible to antibiotics. They are similar to viruses in that they only grow in living cells.

There are three classifications of toxins: plant toxins, bacterial toxins, and fungal toxins. Plant toxins, poisons that are naturally produced by plants, are easy to acquire in large quantifies at minimal cost in a low-technology environment. Bacterial toxins, poisons that are naturally produced through the metabolic activities of bacteria, are harder to produce on a large scale than plant toxins, but they are many times more toxic. Fungal toxins, which are produced by various species of fungi, are much less toxic than bacterial and plant toxins in vapor form, but unlike the other toxins they are dermally active.

The tactical utility of biological agents depends on their robustness, their dissemination characteristics, their persistence (see Box 2-1), their ability to multiply and cause infections, and other factors. There are effective means for protection (e.g., antibodies and vaccines) against some biological warfare agents; however, nations that do not adhere to the BWC and CWC are constantly attempting to modify agents to defeat conventional defenses.

BOX 2-1

Persistence of Biological Agents. Anthrax. Spores are very stable but will be destroyed in a matter of hours by sunlight. The vegetative form is very unstable. Spores remain alive in soil and water for many years. Spores can be killed by dry heat at >284°F (more...)

Proliferation of Chemical and Biological Agents

Both open literature and intelligence assessments indicate that many nations are attempting to develop chemical, and possibly biological, weapons. Although the number of countries that possess CB capabilities is troubling, intelligence assessments also indicate that most of these countries have limited quantities of agents and limited delivery systems. Estimates also indicate that most proliferant countries have neither the industrial infrastructure nor the military logistics capabilities to produce chemical weapons in sufficient quantity to pose an extensive threat to troops with adequate protective capabilities. These countries are, however, capable of producing chemical weapons that can threaten unprotected or minimally protected forces and fixed sites, can be used in terrorist operations, or can be used as deterrents (Commission to Assess the Organization of the Federal Government to Combat the Proliferation of Weapons of Mass Destruction, 1999). Current assessments also indicate that these nations are not likely to possess novel chemical agents or to have weaponized biological agents. Thus, current U.S. protective approaches are likely to be effective.

Intelligence reports suggest that several agents may be in the process of development or weaponization in various countries. With recent advances in biomolecular engineering methods, existing pathogens can be modified to increase their toxicity or to defeat available defensive measures (i.e., vaccines). In fact, biomolecular engineering methods can also be used to modify (i.e., mutate) nonpathogenic organisms into disease-causing agents, thus increasing the potential of biological warfare threats. Because of the rapid developments in molecular biology, the spectrum of biological agents will continue to change, and protective measures will have to be continuously adjusted. Although a detailed review of these developments is beyond the scope of this study (for more information see Ali et al., 1997; DoD, 1996; Rose, In press), they should be kept in mind because they greatly complicate contamination avoidance.

Thickened and dusty agents have been areas of intense research, but the capacity for weaponizing these agents is, as yet, limited. New stabilizing agents have been developed that increase the persistence of a chemical agent and impede decontamination under some conditions. These stabilizers can allow degradation products to recombine into toxic forms at a later time, increasing their potential to affect areas contacted by runoff from decontamination (Ali et al., 1997).

The descriptions of threats posed by proliferant nations sharply contrast the descriptions for the former Soviet Union. Most proliferant countries do not have the research or industrial base to build a large-scale military capability that could threaten deployed U.S. forces, much less the logistical infrastructure to maintain a battlefield capability. However, the threat description on which U.S. requirements are based has changed very little (Eck, 1998).

Production, Weaponization, and Dispersion

Military organizations worldwide have been working on the weaponization of CB agents. Chemical agents engineered for stability can be delivered from spray tanks, artillery shells, or missile warheads. They can also be introduced directly into food supplies, water supplies, and air-handling systems. Ordinarily, biological agents are much more environmentally sensitive than chemical agents and lose their effectiveness quickly when exposed to the atmosphere, and spreading most biological warfare agents from one infected individual to another (with the exception of smallpox) is difficult. The weaponization of biological agents can also be much more difficult than the weaponization of chemical agents (anthrax spores are an obvious exception).

The weaponization of chemical agents, thus far, has been limited to known delivery systems; and current proliferant nations are not likely to have delivery capabilities equal to the capability of the Soviet Union dur ing the Cold War. Thus, even if chemical agents are transferred from a producing country to a nonproducing proliferant nation, the probability of transferring sufficient quantities to threaten massed U.S. forces is low. However, many countries could deploy sufficient amounts of CB weapons to threaten fixed sites and small units (Chow et al., 1998).

Threatened Use of Chemical and Biological Weapons

Proliferant nations could use CB weapons for several purposes: battlefield use against neighboring countries with similar military capabilities; battlefield use against U.S. or other asymmetrically powerful forces; as a weapon of terror; or as a means of changing public opinion. Because of logistical limitations and U.S. capabilities, widespread battlefield use against U.S. forces by nations currently known to have CB capabilities seems unlikely. However, the use of CB agents against neighboring countries or as a terrorist weapon against U.S. forces (especially forces occupying fixed sites) or U.S. peacekeeping teams is a legitimate threat.

Understanding the conditions under which an enemy might use CB weapons is central to the U.S. response. Adversaries in regional conflicts may have very different ideas than Cold War adversaries. For example, they may use CB weapons early in a conflict for political and psychological, as well as military, purposes (Joseph, 1996).

Assessment of Chemical and Biological Warfare Risks

The threat to U.S. forces can be defined as the capability attributed to an opposing force. The risk for U.S. forces is determined through an analysis of the potential interactions of opposing forces. The decision to assume a protective posture is based on several factors, which are parallel to factors in other areas of risk assessment/risk management. The first stage in any risk assessment is hazard identification. In the context of this study, hazard identification requires evaluating the biomedical effects of individual agents on humans. The next stage is threat assessment, which requires determining the capability of an opponent to mount a CB attack and assessing the opponent's intent. The last step is to assess the probability of exposure for deployed forces and assess their ability to protect themselves. Having assessed the risk, one can then develop an approach to managing that risk.

Hazards: Routes and Levels of Exposure

Agents do not pose a hazard to humans until they are introduced into the body through the respiratory tract, the gastrointestinal tract, the mucous membranes, or the skin. The routes of effective exposure for various agents are described in the following Tables 2-5 through 2-11.

Table 2-5

Inhalation/Respiratory Agents.

Table 2-11

Arthropod Vectors.

Effects of Chemical Agents

Inhalation/Respiratory Agents. Chemical agents that present inhalation/ respiratory hazards are delivered as vapors or aerosols. An aerosol is defined as a particle (either liquid or solid) suspended in a gas (air). The particles in an aerosol over time, will be removed from the air and deposited on the ground, on equipment, or on personnel by gravity, inertial impaction, or diffusion. The duration of time a particle can remain airborne and the distance a particle can travel depend on wind, humidity, particle size, and the height at which the particle is introduced into the air.

Vapors can form mixtures with air and can travel over great distances. Because vapors diffuse readily into the air, their concentration tends to decrease over time. Vapors can be removed from the air by diffusion to solid or liquid surfaces or by incorporation on, or in, airborne particles. The effects of inhaled agents are generally proportional to the amount inhaled (dose). For the purposes of this discussion, the effects are considered to be cumulative (a reasonable assumption because these agents are acutely toxic and exert their effects over relatively short time intervals). The dosages are presented in terms of concentration × time (Ct). Thus, an exposure to an agent at a concentration of 30 mg/m³ for a period of 60 minutes would produce a dose of 1,800 mg-min/m³ (see Table 2-5). The dose that was incapacitating to 50 percent of a given population (ID ₅₀), the Ct dose that was incapacitating to 50 percent of a given population (ICt ₅₀), and the Ct dose that caused the defined effect (e.g., edema or death) in 50 percent of a given population (ECt ₅₀) are presented in units of mg-min/m³.

Dermat Absorption Agents. Agents that are delivered as liquids or droplet aerosols can be absorbed through the skin (percutaneous absorption). Most of the nerve agents in liquid or vapor phase and many of the vesicants can be absorbed percutaneously. Thus, many chemical agents can present a hazard even if personnel are wearing respirators. Chemical agents that can be taken up percutaneously are described in Table 2-6.

Table 2-6

Dermal Absorption Agents.

Dermat Necrotic Agents. Blister agents can kill or destroy skin cells causing severe chemical burns. Lewisite causes painful injuries almost immediately upon exposure. Sulfur and nitrogen mustards have a delayed reaction and, therefore, have more insidious effects that may not occur for hours after exposure. The actual delay depends on the intensity of exposure and the area of skin exposed. Dermal necrotic agents are summarized in Table 2-7.

Table 2-7

Dermal Necrotic Agents.

Ocular Agents. Many agents that cause inhalation/respiratory effects are also toxic to the eye, especially vesicant agents, such as sulfur mustard (HD). Available data indicate that temporary blindness could be produced by HD vapor exposures of 200 mg-min/m³. Both GD and GB are known to have ocular effects, but the data are insufficient to establish an ECt ₅₀ (although GD is 2.5 times more potent as a meiotic agent than GB). The data on ocular effects are included in Tables 2-6 and 2-7.

Ingestion/Gastrointestinal Agents. Both food and water sources can become contaminated during an attack, but very little data are available on the effects after ingestion by humans, and information on animal models is spotty at best. At the present time, few methods are available for the rapid detection of chemical agents in either food or water. Toxic effects following ingestion will probably be similar to those after inhalation or percutaneous absorption.

Effects of Biological Agents

Inhalation/Respiratory Agents. Biological agents can be dispersed as aerosols and inhaled. The number of organisms or spores that represent an effective dose for agents known to be distributed in airborne form are summarized in Table 2-8 along with the expected effects and approximate time of onset of effects. The intensity of the exposure could alter the effect and the time to onset.

Table 2-8

Inhalation/Respiratory Agents.

Ingestion/Gastrointestinal Agents. Biological agents can be ingested by hand-to-mouth activities or by the consumption of contaminated food or water. The contamination of foodstuffs can be deliberate or can occur as the result of environmental contamination from a more general attack using airborne agents. Information on ingestion and gastrointestinal agents is summarized in Table 2-9.

Table 2-9

Ingestion Agents.

Percutaneous/Mucous Membrane Agents. The eyes are poorly defended both physically and physiologically and therefore represent a potential route of entry for pathogens. Other mucous membranes are also vulnerable to many agents. The biological agents associated with percutaneous and mucous membrane absorption are listed in Table 2-10.

Table 2-10

Agents Absorbed via Mucous Membranes or the Skin.

Arthropod Vectors. Several threat agents can be carried by arthropods (e.g., flies, fleas, ticks, and mosquitoes). The agent is most often delivered by the insect's ''bite," but other modes of contamination are possible. The number of agent organisms that represent an effective dose delivered by an arthropod and the effects and times of onset are shown in Table 2-11.

Risk Minimization/Protection of Personnel

The most obvious way to minimize risk from exposure to CB agents is to avoid contact with these materials. The military has developed a four-part strategy for protecting deployed forces based on avoiding exposure: sensing, shaping, shielding, and sustaining. Sensing the NBC conditions throughout the joint battle space is accomplished by means of surveillance, detection, identification, monitoring, and reconnaissance. Shaping includes situation awareness of the battle space and managing, assessing, and recording threats (see the Task 2.2 report [NRC, 1999b]). Shielding joint and coalition forces includes medical pretreatment, personal protective equipment (PPE) and collective protective equipment (CPE). Sustaining the force after NBC attacks includes medical treatment and decontamination.

Avoiding contact depends on the capability and availability of detection equipment. Because the lag in detection time of our present capabilities (10 to 15 minutes) is longer than the time it takes to don protective equipment (Table 2-12), (NRC, 1999b), our current capability has been called "detect to treat" (Cain, 1999). A preventive, rather than responsive, posture would be advantageous, of course, but this will require better detection capability.

Table 2-12

Time to Achieve MOPP 4.

In 1998, seven joint CB future operational capabilities (FOCs) (i.e., operational capabilities required to develop war fighting concepts to guide military and industrial R&D) were identified (Payne, 1998). One FOC focuses on the need for detecting and identifying prelaunch indicators, launch signatures, flight paths, and release or impact point(s) of theater missiles, including the ability to distinguish between conventional and NBC munitions. The detection system must provide early and selective warning and must be compatible with the current and future joint command, control, communications, computer, and intelligence (C4I) structure; warning and reporting systems; and NBC battle management systems. Because the FOC is far beyond present detection technologies, personnel must be protected by the combined use of PPE, CPE, and medical protective services.

The military approach to individual protection is embodied in the concept called Mission Oriented Protective Posture (MOPP), an ensemble of protective garments, boots, masks, and gloves. MOPP-Ready status is defined as having protective garments available; MOPP 4 status is defined as all components of the protective ensemble being worn. The progression is shown in Table 2-13.

Table 2-13

Levels of Mission-Oriented Protective Posture (MOPP).

CB battlefield exigencies may require collective protection, a place for medical treatment of casualties and the removal of MOPP gear for eating and recovery periods. Therefore, protective shelters have been developed based on filtering and overpressurization technologies. If individuals or equipment are contaminated, however, they must be decontaminated prior to entry into a collective protection area.

Medical treatments can afford additional protection both before and after exposure (IOM, 1999a). Individual protection, collective protection, and decontamination are three means of risk minimization, and each has an associated doctrinal, training, and R&D component.

Findings and Recommendation

The following findings are based on information provided for this study during briefings and discussions with individuals involved with the CB RDA process.

Finding. Joint structure and joint service processes were developed to maximize the efficient use of funds and to reduce duplications of effort.

Finding. The purpose of the joint prioritization of system needs (and, therefore, RDA needs) is to ensure that fielded systems meet joint service needs. This requires that CINC priorities and NBC community priorities be coordinated.

Finding. The prioritization and selection of RDA projects are often based on compromises or political trade-offs unrelated to CINC prioritization, technical capabilities, or bona fide needs and are focused on service-specific, rather than joint service, needs.

Finding. System development is sometimes based on outdated and possibly inaccurate evaluations of threats and challenges.

Recommendation. The Department of Defense should reevaluate and possibly revise its prioritization process for the development of equipment. The reevaluation should include a reassessment of the use of threat information.

Footnotes

1

Although the NBC defense program addresses nuclear, as well as chemical and biological threats, the National Academies was only asked to address chemical and biological threats. Thus, this report only includes the chemical and biological aspects of CB defense.

2

Contamination avoidance and medical systems are the subjects of separate detailed reports (IOM, 1999a; NRC, 1999b).