Toxic Chemicals and Explosive Materials
Toxic, explosive, and flammable materials provide a wide range of potential terrorist weapons for attacking targets of high value and visibility and for grabbing media attention and causing public panic. These materials can themselves serve as targets during their production, storage, transportation, and use in our highly concentrated manufacturing and transportation systems. Chemical weapons, and chemicals used as weapons, can also be introduced through a variety of ready-made distribution systems, such as those for food, water, and pharmaceuticals.
Nevertheless, we are not without resources for countering these threats: Our current capacity to respond to chemical attacks is substantial. The military is trained and equipped for chemical warfare; industrial and academic chemists have significant expertise in dealing with toxic chemicals; and cities and industries have broad capability in responding to their accidental releases. While this collective know-how is not organized to deal with the threats of chemical terrorism within the United States, it is an excellent starting point for building a reasonable level of preparedness.1
This chapter describes some of the vulnerabilities associated with toxic, explosive, and flammable materials as weapons of terrorism and suggests ways to reduce these vulnerabilities with existing technology as well as through research
initiatives that could lead to new counterterrorism technology. It is divided into five sections: how chemicals can be used as weapons; the general capabilities that are needed to help mitigate vulnerabilities; possible approaches to protecting some key systems (such as food distribution); and responding to terrorist attacks, both for first responders and the medical system. Finally, the value of a dual-use strategy for developing counterterrorism technologies that are also economically viable is briefly discussed.
BACKGROUND: CHEMICALS AS WEAPONS
Chemicals continue to be weapons of choice for terrorist attacks. They are readily available and have the potential to inflict significant casualties (from a few to perhaps many thousands in technically possible, if improbable, high-end attacks). And they have characteristics that make them attractive for deployment against an open society: easily concealed, undetectable at a distance, and visually indistinguishable from materials in everyday use. Moreover, the potential for their use causes anxiety. While chemical agents may not have the potential to produce the widespread casualties and destruction that could be caused by epidemic biological agents or nuclear weapons, they are more readily available and can cause significant deaths and injuries and disruption in a local area. Historically, problems of delivery were considered a serious barrier to the use of chemical weapons in warfare, and this has been assumed to be a significant constraint on their use by terrorists. But improvements in the technology for disbursing the agents, the willingness of terrorists to commit suicide, and their focus on killing as many people as possible rather than on targeting a specific person or persons, make the danger of attacks with chemical agents a serious threat.
The most plausible use of chemicals as weapons is in attacking aggregations of people in enclosed spaces (e.g., in subways, airports, and financial centers) in ways that would cause disruption to crucial infrastructure services or render them unusable (closing down transportation or financial systems, for example) and potentially causing widespread loss of confidence in the government’s ability to protect its citizens. Small quantities of chemicals would usually be all that would be needed (for nerve agents, a few hundreds of grams would suffice). Use of a chemical agent in a nonenclosed space, however, is perhaps of less concern, because a toxic cloud would be subject to the vagaries of wind direction and thermal currents, thereby requiring large amounts (many kilograms) of the agent to cause numerous casualties.
Other ways to use chemicals as weapons include attacking people indirectly by contaminating facilities. Nonvolatile chemicals can be very persistent and thus able to taint their targets—and interfere with critical services—for long periods of time.
Harmful agents could also be delivered through existing systems already designed for rapid and widespread distribution, such as the postal system or the
food and water supply networks (the latter two are discussed in more detail later in this chapter). The anthrax attacks in the fall of 2001 demonstrated the effectiveness of using such systems both to harm people and disrupt an important service. A concerted attack from multiple locations could have resulted in widespread contamination of many of the automated centers where mail is sorted and distributed, resulting in large numbers of infected mail workers and recipients—and possibly even shutting down the U.S. Postal Service. Countless businesses could also have been contaminated. Other mass-distribution systems—currency, newspapers, and junk mail, for example—might also be used to expose large numbers of people to the effects of infectious or toxic substances or to interfere with the functioning of society.
A wide variety of chemicals—including many in common use—could be used as weapons. There are three major classes of such chemicals:
Chemical weapons (CW), developed by states for military use; 2
Toxic industrial chemicals that are produced, transported, and stored in large quantities in the civil economy; and
Explosives and highly combustible materials.
These three classes of chemicals are discussed below.
Military Chemical Weapons
Chemical weapons were first used in World War I and drew on existing industrial chemicals (chlorine, phosgene). In the period after World War II, a number of countries (especially the United States and the Soviet Union) continued to develop chemicals specifically designed as weapons: The most important of these are the so-called nerve agents and blister agents (e.g., sarin and mustard gases). A number of such chemicals have been produced, and they can be delivered in a variety of ways, including sprays, rockets, mortar shells, mines, and other explosive devices. Several of these chemicals were designed to have very high toxicities (Table 4.1).
Chemical weapons were not used in World War II, and the United States discontinued its CW programs in the 1960s, at least partly on the grounds that CW were not militarily effective. The Soviet Union reached a different conclusion and continued, up to the 1990s, to develop chemical weapons for military use. In fact, chemical weapons appeared to be a standard part of Soviet operational doctrine, with special utility in slowing and blunting offensive operations,
Some biological and radioactive agents are occasionally considered in this chapter along with chemical agents because the responses to attacks with them would be similar. Such biological agents include botulinum toxin, staph enterotoxin, and ricin. Radioactive agents, in this context, mean dispersible radioactive materials (as distinct from nuclear weapons); they are discussed in Chapter 2.
TABLE 4.1 Approximate Toxicitya of Selected Chemical Agents
2,000 to 4,500
aFor respiratory exposure to vapor or aerosol; other forms of exposure are also possible (e.g., skin exposure or ingestion).
bAbbreviations in parentheses are common military designations.
cDosages expressed as concentration × time (Ct) in units of mg-min/m3. LCt50 refers to a dosage that is lethal to 50 percent of the exposed population; ICt50 refers to a dosage that is incapacitating to 50 percent.
dThe incapacitating dosage depends on the concentration.
SOURCE: NRC (1999), p. 69.
damaging logistics systems, and attacking the cities of adversaries. Large portions of the Soviet technology are now presumed to be widely available to other countries and to an unknown but probably growing number of nonstate groups.3,4
The Chemical Weapons Convention, ratified by more than 160 nations (including the United States) in 1997, has the objective of eliminating chemical weapons from state production, storage, and use. It was not specifically designed to reduce terrorist activities. However, it is likely to have some impact because it reduces the availability of CW, as they are destroyed under the observation of the Organization for the Prohibition of Chemical Weapons (OPCW). In addition, certain chemicals and equipment that could be used to produce CW must be routinely reported, and facilities producing them must be inspected. These requirements present a terrorist with obstacles to producing and concealing the production of CW. Further, nations that are members of the OPCW are prohibited from trading with nonsignatory nations—which currently include Iraq, Libya, North Korea, and Syria, among others—in certain chemicals used as precursors.
Despite some protection afforded by the Chemical Weapons Convention, military chemical weapons—and chemicals that can be used as weapons—must still be assumed to be relatively available. Dedicated and trained terrorists might obtain chemical weapons from nonsignatory and noncompliant nations, or synthesize the agents themselves (Scientific American, 2001). Making chemical weapons requires some technical skill, but over time much of the information required to make these materials has drifted into the public domain. The most toxic of the common weapons—the nerve agents—can be made using relatively unsophisticated facilities and in quantities sufficient for terrorist attacks (although large-area attacks requiring tons of agents would require large-scale facilities available only to states or large corporations, not to individuals). There are a number of sources that a terrorist might use to get the information needed to make chemical weapons, including the Internet.
The Aum Shinrikyo attack on the Tokyo subway system in 1995—using sarin—proves that fabrication and use of chemical weapons by nonstate groups is now possible and can inflict significant casualties. Twelve people were killed and more than 5,000 injured in this attack (Kawana et al., 2001), and many more would have died if the terrorists had been more sophisticated in their use of the chemical agent. The deployment of chemical weapons is now more a question of the attacker’s objectives and competence than of the effectiveness or availability of the technology. In the hands of skilled terrorists, especially if they are willing to die in the effort, CW attacks could be devastating.
Every industrialized country is heavily reliant on chemicals. The United States is no exception; it produces, stores, and transports large quantities of toxic industrial agents. Certain of these (such as chlorine and phosgene) have actually been used as chemical weapons, as noted above; others (volatile acids, certain industrial chemical intermediates) could cause numerous casualties if released in cities in large quantities.5 Although the safety record of the chemical industry is very good, these chemicals nevertheless pose inherent risks.
Over the last 20-30 years, significant changes in the chemical and petroleum-refining industries have taken place, driven both by economic and regulatory factors; some of these changes have inadvertently helped to reduce the risks that hazardous materials might be used by terrorists. For example, the movement toward just-in-time supply of materials, while made to reduce costs, has also
reduced inventories of hazardous chemicals stored at manufacturing sites. Innovations involving less-toxic starting materials, intermediates, products, and by-products have lowered intrinsic dangers to workers, the public, and the environment and at the same time reduced the availability of materials that might fall into the wrong hands. Over-the-fence manufacturing—whereby the supplier builds a plant immediately adjacent to the customer’s plant, or even on the customer’s site—provides a reliable source of materials while minimizing transport and storage. Probably the most significant change has been the ability to monitor and control reactions on a real-time basis; real-time control reduces the chances for accidental or intentional releases. These trends show that many technical changes intended to increase efficiency, reduce environmental impacts, and improve safety can also reduce the threat of terrorist attacks.
Despite these advances, the volume of toxic materials in production, transport, and storage is still enormous, and as a result there are still many hard-to-protect targets. Chemicals could be released from industrial facilities or pipelines, for example, using explosive charges or simply by cutting pipes or opening valves. Under some meteorological conditions, release from production and storage facilities could permit a toxic plume to pass over heavily populated areas. Transportation systems (e.g., railroad tank cars, ships and barges, and trucks) allow rapid transport of hazardous chemicals, and terrorists could take advantage of these vehicles’ frequent proximity to potential targets (e.g., trains that travel under cities or barges located in harbors) (see also Chapters 7 and 8).
Thus new technologies or further incentives to reduce the amount of toxic materials being moved around the country would be very useful. Taxes placed on transport and storage of highly toxic chemicals, combined with public-private research partnerships, perhaps managed by EPA, could be used to encourage the development of new approaches to on-site and just-in-time production. For example, new process technologies to allow small-scale production of chlorine at water-treatment plants could greatly reduce shipments of this hazardous material.
Explosives and Flammable Agents
Explosives, having many legitimate purposes and being relatively accessible, pose a significant terrorist threat (NRC, 1998). They can be used in large quantities to produce mass destruction, as in the attack on the Murrah Federal Building in Oklahoma City, and in smaller quantities to destroy sensitive or symbolic targets such as airplanes, bridges, or key components of critical infrastructures (e.g., telecommunications networks, electric-power grids, and water supplies). Legally mandated controls apply to industrial and civil engineering explosives, but the quantities in use are large and the control mechanisms imperfect. More important, as the Oklahoma City attack shows, very powerful explosives can be readily assembled from such otherwise innocuous ingredients as agricultural chemicals and fuel oil.
Flammable materials include gases and volatile liquids that could be formed into a vapor cloud and ignited to cause a fire or detonation. They are in common use across the United States for fuel, industrial feedstocks, and a variety of other applications and could be released from production, storage, or transport facilities.
As with industrial chemicals, the distribution systems for explosives and flammable agents are vulnerable to attack. These systems include trucking and shipping networks (especially liquefied natural gas tankers and their shore facilities), railroad lines, pipelines that carry natural gas or other gaseous or liquid hydrocarbons, and underground sewers or utility tunnels. These systems are all susceptible to hijacking and use of explosive or flammable materials as weapons, or to physical damage, with consequent disruption of service. In some cases, injuries and environmental damage may occur near where a pipeline is breeched.
Underground sewers or utility tunnels could be used as conduits for releasing toxic, flammable, or explosive materials. Chemicals could disperse through these systems and eventually emerge from manholes, drains, and other openings, or they could ignite or explode under streets and near buildings (see Chapter 8). Another potential dispersal mechanism is a subway system. Materials in the subway tunnels could be “pumped” through the city by the trains—a particularly effective method for delivering powderized materials like anthrax, but it might also work for spreading chemical agents.
GENERAL CAPABILITIES NEEDED TO HELP MITIGATE VULNERABILITIES
Sensors and Operational Systems for Detecting and Characterizing Chemical Agents
Improved and expanded use of sensors must play a major role in preventing catastrophic terrorism or, if attacks do occur, in minimizing their impacts. Sensors have the potential to thwart terrorist activities in the planning stage, or before or during attempted attacks, and to help identify individuals with malicious intent. They may also be useful in forensic analysis to identify perpetrators after an attack.
Possible applications include the following:
Sensors to help provide sensitive and rapid warning for the protection of fixed sites (subways, airports, government buildings, financial centers, high-value industries). For example, sensors for ventilation systems capable of detecting deviations from normal conditions and monitoring for chemical and biological agents could be coupled to rapid-shutdown procedures, especially at the final vent (see Chapter 8);
Development of new and improved sensors should provide many security benefits, but perhaps none is so visible and immediate as the need for increased airport security with minimal passenger inconvenience. Until recently, security at U.S. airports was limited to metal detectors and x-ray imaging. But over the past few years, explosives detectors have been installed that use stationary ion mobility spectrometers (IMSs) or chemiluminescence sensors, both of which are capable of detecting a number of explosives, including RDX (1,3,5-trinitro-1,3,5-triazacyclohexane), PETN (pentaerythritol tetranitrate), TNT (2,4,6-trinitrotoluene), and nitroglycerin. However, given the limited sensitivity of deployed detectors (detection limits of 1-10 picograms) and the low volatility of most explosives, these systems generally require the collecting of particles of explosive for detection. Particle collection requires tedious swabbing of luggage, and careful cleaning of the exterior of a package by a terrorist can greatly reduce the chance of detection. Another limitation of conventional technologies is that particles can be picked up from one object by another, causing a false positive.
However, new and emerging techniques could augment existing detection capabilities. A number of new technologies appear to hold promise for explosives detection, including x-ray diffraction, which detects several types of explosives; microwave/millimeter wave scanners; and nuclear quadrupole resonance (NQR) (NMAB, 2002). The use of NQR spectrometry or neutron capture for explosives detection is based on the unique physical nature of the 14N nucleus (99.6 percent natural abundance) in the nitro groups in the explosive materials. New detection-coil technologies have improved NQR considerably, and the U.S. Army is developing vehicles that use it for landmine detection. However, NQR still suffers from limitations. It has sizeable power and computational requirements, making it unsuited for a portable system. The long relaxation times of the 14N in TNT restrict the number of pulses that can be applied and thereby limit sensitivity for this explosive; there is also a reluctance to expose people to strong radio frequency fields. Neutron capture methods require a neutron source, such as a radioisotope or a particle accelerator, and present other complexities.
Methods to detect explosive vapors have many advantages: Vapor collection from people and luggage can be rapidly accomplished and is minimally invasive. Such detection needs considerable sensitivity, as is provided by mass spectroscopy, and may require new sensor advances. It will also be important to have high-sensitivity systems—unlike IMS, chemiluminescence, NQR, or neutron capture—that are portable and can be used as a handheld wand.
Additional support is needed for research to develop improved methods for detecting explosives at airports.
Portable sensors to allow first responders to assay levels and types of hazard at a distance—that is, to allow them to make correct initial assessments without themselves becoming casualties (see Chapter 8);
Mobile sensors to be used in mapping the extent of a cloud of a volatile agent and to guide civil authorities in controlling population movements;
Sensors to assist physicians in determining the extent of exposure of patients presenting at hospitals (see Chapter 3); and
Sensors to assess the level of contamination following an attack and, more importantly, to determine when a site is safe and can be returned to normal function.
As can be seen from the above list, the use of sensors is not limited to the detection of chemical agents; the detection of biological agents and of fissile and radioactive materials is discussed in Chapters 2 and 3. Current sensor capabilities are fairly limited; in many cases, the best “technology” for practical use continues to be trained dogs. Manufactured sensors are often designed for use in specific environments and to be selective for only one or two chemicals. Yet because there is a spectrum of possible threats, sensor systems are needed that can detect a large number of possible chemicals. And, given the ultrahigh toxicity of some of these chemicals, detection systems’ sensitivities must be significantly increased. In addition, sensor systems will need a number of different subsystems, including sample collection and processing, presentation of the chemicals to the sensor, sensor arrays with molecular recognition, sophisticated signal processing, and amplification of the transduction events.
Sensor programs funded by the government have not yet produced significant increases in counterterrorism capabilities, in part because the focus has been on the sensor itself and not on the overall system for detecting threats. There is a strong need to focus on systems approaches here—to explicitly consider how the sensor system will be used, by whom, for what purpose, and at what cost. While the common goals for virtually all sensors are that they be less expensive, more versatile, more reliable, and more compact, each of the potential applications listed above will have a different set of most-desired characteristics for a sensor system, and development efforts should recognize what trade-offs (between, say, size and versatility) each application demands (see Chapter 11).
One example of a factor that needs to be considered in sensor development is the relevant time scale. Chemical agents have a broad range of times required for their toxic effects to appear. One of the most plausible types—nerve agents—acts rapidly; evidence of toxicity can appear in seconds to minutes, depending on concentrations, exposures, and agent. Similarly, many industrial chemicals (e.g., chlorine, hydrochloric acid) that might be used as improvised chemical weapons are immediately apparent through smell or effects on eyes or mucus membranes at concentrations well below that required for serious toxicity (but if escape from them is not possible, the resulting damage to lungs becomes evident over time).
Some chemical agents, such as mustard gas, for example, have symptoms that appear much more slowly (NRC, 1999). Unconventional agents (e.g., aflatoxins, which can induce cancer in some exposed individuals) might not have observable effects for years. Effective responses to chemical attacks, and to biological attacks as well, need to be tailored to the specific agent involved; thus the choice of the right sensor(s) for the job at hand—whether with respect to the time scale or to other factors—is crucial.
In the United States, government-supported research on sensors is now mainly funded through DOD (DARPA), NSF, and DOE and has produced some significant advances in the sensitivity and other characteristics of the sensors themselves. In particular, sensors with medical applications have reached the market fairly rapidly, even though the DOD programs have focused mainly on military problems (e.g., standoff and point detection in field operations) and military customers. Development of sensors is heavily supported by industry as well, and industrial production facilities are routinely equipped with instrumentation that can detect and identify releases of toxic materials. However, none of these technologies has had any real impact on emergency preparedness, as the market for such applications is small and fragmented. For sensors to be effectively implemented for homeland security, they will need to be inexpensive, widely deployed, and networked.
Thus, although improved detection does not rely on sensors alone, research on sensors being conducted by many agencies, companies, and universities—including, but not limited to, work on sensors to detect explosives—should certainly continue. There are rich opportunities for discovering new technological principles on which sensors might be based.
Recommendation 4.1: A broad-based research program should continue to look for promising new principles on which better sensors might be based.
Presently, trained dogs represent the best broad-spectrum, high-sensitivity sensory systems. Dogs are capable of detecting many more items of interest, including people, explosives, drugs, fuels, and disease, and at lower concentrations than currently manufactured sensors. But the precise chemical signals that provoke responses in dogs remain uncertain; it is likely that the signals are not from a single compound but rather from multiple compounds. In the short term, the use of dogs could be expanded, and dogs could be trained to detect a wider array of targets. In the longer term, however, detailed studies to better understand the abilities of dogs could be useful in designing more broadly effective manufactured sensor systems.
Recommendation 4.2: Basic research to study how animals accomplish both detection and identification of trace chemicals should be pursued. These efforts could yield new concepts for better automated systems to reduce our dependence on the use of dogs for detection.
If sensor research is to move forward efficiently, mechanisms to focus and exploit the highly fragmented array of existing programs will be needed. In addition, there should be increased emphasis on converting demonstration systems into practical, commercially available products that can increase the ability of responders to do their jobs safely and efficiently. Model mechanisms for helping to bridge the gap between sensor research and the development of implementable systems include the NIST Advanced Technology Program (ATP), the Small Business Innovation Research (SBIR) programs in place at several agencies, and the DARPA Advanced Concept Technology Demonstration program. Such programs could decrease the commercial risk of developing new types of sensors; government-sponsored purchases of sensor/detector systems to test their utility with first-responder groups would also be of value.
Recommendation 4.3: A new program—with sustained funding—should be created to focus and coordinate research and development on sensors and sensor networks, with an emphasis on the development of fielded systems.
This program should build on the sensor research under way at many agencies and should also include plans for commercialization (favoring dual-use systems) and be backed by exercises, simulations, and testing to establish reliability.
New technologies that offer significant advances need to be constantly evaluated. But evaluating sensor systems is difficult because their effectiveness depends on the operational environment and on who will be using them. Attention must be paid to the way systems are deployed and how alerts from sensors are displayed; people with less specialized training, such as emergency responders, would need different system performance characteristics and require different kinds of information than those with more experience, such as chemical professionals and plant operators.
Recommendation 4.4: Because a bewildering array of counterterrorism technologies (including various kinds of sensors) is coming onto the market, the federal government should oversee a technology testing and verification program that could guide federal research investments and advise state and local authorities on the evolving state of the art.
Data Networks and Processing
In many cases, efforts to prevent terrorism will involve large data streams—from arrays of sensors, for example. It is important to be able to efficiently process and mine the data for useful information, so as to quickly distinguish patterns of actual threats from noise or natural events and to make the information systems accomplishing these tasks secure. These issues are discussed in Chapters 5 and 11.
Improved Filters, Absorbents, Scrubbers, and Membranes for Chemical Decontamination and Restoration of Function
In most cases, the impact of a chemical attack would not be limited to the harm done at the time of the attack. Afterward, it could take a long time to decontaminate the site, as well as to restore public confidence. Restoring the Hart Senate Office Building after it was contaminated by anthrax exemplified the difficulty of decontamination in the wake of a biological attack. Comparable efforts following a chemical attack would be different, but not necessarily easier. Contamination by a volatile agent (e.g., sarin) presents the problem of removing a toxic vapor without releasing it into the outside environment. Contamination with a persistent agent (e.g., VX) poses an additional concern—much of the agent may deposit on surfaces, and the chemicals used in decontamination, such as hypochlorite solution, are generally incompatible with electronic equipment and paper. Regardless of the type of contamination, however, persuading the occupants of the building to reenter and go back to work will require credible technical evidence that it is safe to do so.
Research is needed to identify more effective technologies for removal of contaminants from different media (air, water, and solid surfaces) and to quantify their effectiveness so that appropriate decontamination measures can be developed. These technologies are likely to be specific for the contaminants involved and for the media in which they are dispersed. Contaminants in air or water—chemical, biological, or nuclear—may be present as aerosols (particles of solid or liquid) in air or as particles in water, or they may be homogeneously dispersed, as gaseous contaminants in air or dissolved contaminants in water.
Particles may be removed by filtration, with the specific technology depending on particle size (Accomazzo et al., 1988; Ensor, 1988). Several filtration technologies are available: micro-, ultra-, and nanofiltration membranes for treating contaminated water and HEPA (high-efficiency particulate air) filtration for contaminated air. Improved high-efficiency and low-pressure-drop filter systems could be useful in rapidly treating large volumes of particle-contaminated water or air.
Homogeneously dispersed contaminants may be removed by absorption,6 adsorption,7 chemical reaction/neutralization, or selective membrane filtration (Ho and Sirkar, 1992; Majumdar and Sirkar, 1988; Prasad and Sirkar, 1987; Way et al., 1982). Absorbers and filters can be used both to prevent toxic chemicals
from entering a facility through the ventilation system and to decontaminate a building after an attack. Carbon adsorbents and molecular sieves (zeolites) are conventional adsorbents; their effectiveness for specific contaminants must be determined and documented. Special adsorbents may need to be developed for hard-to-remove contaminants. Absorption techniques may be used for removing gaseous contaminants from air in conventional scrubbers/packed columns using appropriate solvents. Reactive packed-sorbent (reagent) beds may also be used for removing contaminants from water or air by chemical reaction/neutralization. A need exists to identify appropriate contaminant/sorbent combinations and possible interference factors, e.g., humidity. Some dissolved contaminants may be removed from water with selective membrane filtration; however, membranes require a concentration gradient that may not be available for rapidly dispersing dilute contaminants. Membrane techniques based on preferential diffusion of contaminants will thus be highly specialized for specific contaminants. Microporous membranes may, however, be combined with an appropriate reactive absorbent/adsorbent for the removal of contaminants by facilitated transport.8 In such an application the membrane simply provides a large surface area for effective and efficient removal of dilute contaminants.
Another area of need is for better methods to contain and neutralize clouds of airborne toxic materials such as ammonia, chlorine, hydrogen fluoride, hydrogen sulfide, and sulfur dioxide. Work to date has shown that large quantities of water must be sprayed in the air to “knock down” any significant portion of such airborne chemical clouds (Dandrieux et al., 2001; Petersen and Diener, 1990). The use of reactive foams in existing fire-suppression systems to counter chemical and biological agents should also be explored.
Recommendation 4.5: Universities, companies, and federal agencies should work together to improve existing technologies and develop new ones for removing chemical contaminants from air and water. Research is especially needed on filter systems capable of treating large volumes, novel media that can help prevent toxic materials from entering facilities through ventilation systems, and methods to contain and neutralize clouds of airborne toxic materials.
The problem of decontamination has been studied for many years at DOD, the national laboratories, and universities. While new approaches may be found in areas already being explored, it is possible that better solutions could lie in
some entirely new direction—e.g., chemically “hardened” surfaces that are non-adsorbing and easily cleaned.
Recommendation 4.6: Under the lead of DARPA, DOE, and NSF, exploratory programs should be initiated in new approaches to decontamination, including hardened structures, protective systems for microelectronics and other expensive equipment, and environmentally acceptable ways of disposing of contaminated material that cannot be cleaned.
In addition to new and advanced technologies for decontamination and filtering, attention must also be paid to low-technology approaches for the protection of both people and buildings. In a large-scale chemical attack, timely warning and advice about appropriate countermeasures could make a significant difference to those potentially exposed. Such countermeasures often involve passive protection (masks, sealed rooms) when levels of contamination are relatively low, yet there are currently no U.S. standards for such protection.
Recommendation 4.7: Working in coordination with others as needed, NIST should take the lead on developing standards and technologies for the passive protection of individuals, rooms, and buildings against chemical, biological, and radiological threats. The developers of such technologies should consider factors such as cost and accessibility to all sectors of society.
Many of the tasks involved in counterterrorism, such as the assessment of attack sites, inspection of containers at borders, and routine surveillance of facilities, are potentially dangerous and dauntingly labor-intensive. Robotic technologies could spare humans from dangerous work, substitute machine time for human time in surveillance, and perform other important functions. Robotic technologies have matured substantially in recent years, but the prospect of robots as autonomous systems, performing complex tasks without human supervision, seems somewhat remote. However, the idea of robots (and especially networks of robots) as helpers for emergency responders does seem plausible, given sufficient investment.
Robots could assay damage and rescue casualties in a contaminated environment, carry out decontamination (especially if the process used in decontamination is itself hazardous), and inspect spaces inaccessible to humans (e.g., the interiors of shipping containers). Cities, where terrorist attacks are most likely to occur, provide an ideal environment for robots: There is ample power, the topography of the landscape is predictable, and other resources that might be needed (e.g., decontamination solutions, supervision by human specialists) are readily available (see Chapter 11).
Recommendation 4.8: Agencies with experience in robotics, such as DARPA, should support research on all elements of robotic systems—including sensors, networks, and data communication and analysis. The aim would be to develop robots to assist in chemical (and biological or radiological) defense, thereby reducing hazards to humans and increasing the capabilities of defensive systems.
MITIGATING VULNERABILITIES OF SPECIFIC SYSTEMS
Technology to Secure Industrial Chemicals and Chemical Production and Storage Sites
The chemical industry and the government have been making substantial efforts since September 11 to increase security preparedness. Industry is carrying out joint assessments with the FBI, EPA, Coast Guard, FEMA, the Bureau of Alcohol, Tobacco, and Firearms (ATF), and the Office of Homeland Security. Aspects under examination include security checks of personnel, controlling access to sensitive areas and materials, increasing surveillance, reviewing and changing distribution routes, and reducing quantities of hazardous materials in storage and transit. The experience of large companies in preventing and responding to accidental releases of chemicals is relevant to defense against chemical terrorism; these companies are highly regulated with respect to the reporting and inspection of processes, products, record keeping, shipments, storage, and use, and they have much of the infrastructure required. But smaller companies lack such broad infrastructure for increased security and response; mechanisms by which the government or larger companies could provide expertise and advice might therefore be helpful.
The cast of players is even larger. In the past, security issues were primarily the purview of those who produced hazardous materials; now, transporters and users (including private and government laboratories and educational institutions) must be included in the security chain. This means that industries dependent on hazardous materials (such as mining, construction, electronics, manufacturing, food processing, agriculture, the medical industry, and transportation) will need to pay attention to security concerns as well.
The best defense against misuse of chemical, explosive, and flammable materials is adequate security around the facilities that handle them and in the transportation systems that distribute them. Heightened surveillance and improved techniques for detection and identification of leaks or illegitimate use will help prevent hazardous materials from being acquired, released, or rerouted. But progress beyond the immediate tightening of security will require systematic assessment of vulnerabilities in the complex systems by which we produce, store, and transport chemicals.
Issues requiring careful analysis include the following:
Industrial plants have not been designed to withstand well-executed attacks involving a number of people, nor is there thorough understanding of (or protection from) the damage that might be done by a well-placed, knowledgeable person within a facility.
Many industrial operations are controlled by supervisory control and data acquisition (SCADA) systems—computer systems designed to automate and control plant functions. These systems stress interoperability more than security, and a better understanding of how to improve their ability to resist cyberattacks is needed (see Chapters 5 and 11).
Large quantities of hazardous industrial chemicals are shipped daily in the United States—by truck, rail car, and barge. These shipments often pass through cities or are stored in (or close to) cities. Understanding how to secure these shipments—either by protecting them or by routing them around cities—is important in preventing them from being hijacked and used as weapons (see Chapter 7).
Recommendation 4.9: The Departments of Transportation and Commerce, working with industry and with federal and state law enforcement agencies, should be tasked with developing plans for regulating the movement of hazardous materials through and near cities. These plans should incorporate technologies that allow detection of anomalies in handling and movement.
Ammonium nitrate and urea are used in very large quantities for agriculture and can also be used as explosives—ammonium nitrate was used in the truck bomb that brought down the Murrah Federal Building. British scientists and others have worked for some years to find a way to alter this chemical so that it retains its agricultural benefits but is no longer an effective explosive. This research has not been successful to date, and practical, new approaches to this problem would certainly be welcome (NRC, 1998).
Protecting Food Supplies
Consumers in the United States are very sensitive to suggestions that the food supply might not be perfectly safe. Widely publicized episodes, such as the concern about the pesticide Alar on apples, debate about the safety of genetically engineered food, and ripple effects caused by the association of beef with mad cow disease, exemplify this highly charged social environment, and a good deal of attention is being paid to ensuring safety and purity throughout the various stages of food production, processing, and distribution.
However, protecting the food supply from intentional contamination has not been a major focus of the U.S. food industry. Three characteristics of this industry create vulnerabilities to terrorist attack: the concentration of primary produc-
tion in large, monoculture farms; the concentration of commodity food-processing in large centralized facilities; and a tendency to adhere to rigidly defined patterns of quality control that may not detect unanticipated contaminants.
Food production and processing offer many potential avenues for terrorist attack. Protection of the U.S. food supply is generally the responsibility of the Food and Drug Administration (FDA), which is progressively replacing old quality control (QC) and quality assurance (QA) programs with a new methodology called hazard analysis and critical control point (HACCP).9 In earlier QA/QC methods, samples were drawn from food lots according to a statistical protocol. These lots were then held, pending the results of testing, and released only after each lot passed all tests. HACCP is a system designed to enhance food safety by identifying sources of possible contamination and specifying ways to control them—through changes in source, process, procedure, or structure. HACCP was designed to prevent unintentional contamination, however, and not to deal with intentional contamination. Extending the existing HACCP program so that it can be effective against deliberate tampering will require a multidisciplinary reassessment.
Recommendation 4.10: The FDA should act promptly to extend hazard analysis and critical control point (HACCP) methodology to enable it to deal effectively with deliberate contamination of the food supply.
Primary food-production facilities need to be secured from contamination with toxic or infectious agents, but only to an extent commensurate with the hazard—that is, the number of people that might be involved, their likely rate of consumption of the contaminated food, and the time delay from contamination to consumption should all be considered. The time delay is especially important, because contaminated foods consumed slowly over time (such as canned goods) would cause few illnesses or deaths per unit time. Thus, there would be an opportunity to determine the source of the contamination and the lots affected and to accomplish a recall—thereby reducing the consequences of such an attack. By contrast, foods consumed quickly (such as milk, bread, and fresh meats and vegetables) would be less effectively removed by recall, so their production facilities require more security.
Recommendation 4.11: The FDA should develop criteria for quantifying hazards in order to define the level of risk for various kinds of food-processing facilities. The results could then be used to determine the minimal level of protection required for making each type of facility secure.
This approach, sometimes called “graded security,” would define the extent of security measures needed, with the severity increasing in proportion to the risk. It might be conceptually similar to the classification system created by NIH for laboratories working with biohazardous agents.
Recommendation 4.12: The FDA should convene panels of experts in major areas of food production to assess vulnerabilities and recommend corrective actions. This effort should be pursued with as much cooperation as possible from industry, but it should not be left to industry alone.
Protecting the Pharmaceuticals System: Excipients and Unregulated Diet Supplements
Following the 1982 poisoning incidents in which cyanide-laced Tylenol was placed in retail stores in the Chicago area, tamper-evident packaging became required for all over-the-counter medications. As a result, deliberate contamination of distributed nonprescription drugs has become far more difficult. Similarly, to successfully tamper with FDA-approved drugs before distribution, a terrorist would have to defeat the relatively rigorous controls established for routine drug production.
A greater risk, however, is contamination of the vast array of vitamins, health supplements, and “natural” remedies, which do not need FDA approval. The chance prevention, in 1998, of a mailing in which sodium cyanide was deliberately sent packaged as a free sample of a nutritional supplement (Canto, 1998) underscores the vulnerability of these products.
The manufacturers of pharmaceutical products are required by law (21CFR211) to establish and maintain controls over personnel, facilities, and materials (including all raw materials, intermediates, and final products). Such controls are also mandated for producers of active agents subsequently compounded into medications and, to a limited degree, for the producers of excipients.10 Controls include physical management of material movement and use, especially inventory reconciliation; worker training and qualification for assigned tasks; and strict monitoring of water and air systems within production environments.
The ability of such controls to protect products against deliberate contamination before distribution is clearly dependent on the nature and concentration of the contaminant. Acute poisoning of consumers requires materials and doses different from cumulative or delayed-effect toxins or from radioisotopic substitutions, all of which present more insidious threats. Excipients in particular often
account for a relatively high fraction of the final dosage form, thus allowing for lethal contamination at low concentrations. Moreover, they are widely used: Several are common to more than a hundred approved drug formulations. While there are multiple suppliers of excipients, contamination of one source could have a widespread impact, including an erosion of public confidence in the safety of medicines generally.
Although assay methods are not likely to be published for proprietary active agents (published materials do exist for testing of generic drugs), they often make up a small weight-fraction of the final dose and are less susceptible to deliberate contamination.
Recommendation 4.13: The FDA, working with the pharmaceutical industry, should lead a review of the security and inventory controls used by manufacturers of drug excipients and health supplements to determine if current methods and standards need to be improved.
Recommendation 4.14: The FDA should facilitate efforts to develop improved technologies for detecting deliberately introduced contaminants in food or drug products. It should direct special attention to technologies capable of simultaneously assessing a range of potentially harmful components.
Protecting Water Supplies
Within the nation’s infrastructure the U.S. water supply is probably not the most likely terrorist target for producing mass casualties, because the combination of high dilution and water treatment provides protection against many threats. However, forced entry of a highly toxic agent into the system after water treatment could have serious consequences. Chapter 8 discusses the structure of the nation’s water systems and provides recommendations for reducing system vulnerability. Here the focus is mainly on issues related to rendering potential contaminants harmless.
Many agents can cause death or serious illness when introduced into a water system (WHO, 1970; Burrows and Renner, 1999; Clark and Deininger, 2000), the most dangerous being bacteria and toxins.11 Among the most harmful bacteria are Bacillus anthracis, Shigella dysenteriae, Vibrio cholerae, and Yersinia pestis (NRC, 2000). The best line of defense against them is to maintain a chlorine residual in the water distribution system. Of several toxins, the botulinum toxin is the most lethal (NRC, 2000), but doses required for adverse health effects are not very well defined. Data are available only for mice and primate
Chapter 3 provides more details on biological agents, which are mentioned here because of the similarities in surveillance, detection, and prevention of both biological and chemical threats.
models and are usually expressed as an LD50 (lethal dose for 50 percent of the exposed subjects). The appropriateness of the LD50 is uncertain; some scientists believe that an LD10, or even lower, might be more prudent.
Besides bacteria and toxins, there are a number of other potential contaminants of the water supply. Chemical-warfare agents are normally deployed as aerosols, so contamination of water can be a secondary effect (NRC, 1995). Because many of these agents hydrolyze in water, especially under alkaline conditions, they are eventually rendered harmless. However, some insecticides that are choline esterase inhibitors, similar in action to nerve agents, do persist in water (Larsson, 1958).
Natural outbreaks have provided us with experience in dealing with some biological contaminants. For example, one natural outbreak of the protozoan Cryptosporidium parvum contaminated the Milwaukee water supply system in 1993, with serious consequences: Over 50 people died and over 400,000 became ill (Hoxie, 1997). Although this protozoan causes serious health effects in people who are very young or old, or immunocompromised, it does not pose a lethal threat to most healthy people.
Most of the agents that can be introduced into a water supply system will react with a disinfectant residual.12 (While chlorine is the most commonly used disinfectant in the United States, other chemicals such as ozone—each with its own advantages and disadvantages—can also be used.) Even if reaction and deactivation of a contaminant are incomplete and take time, maintaining a residual of disinfectant in the distribution system is the most important measure for its protection. The residual needs to be monitored at representative locations in real time. The technology is available for this monitoring, but questions remain about the residual itself. Would the level of chlorine necessary to react destructively with most biological agents make the water undrinkable? If so, could the chlorine be removed easily and inexpensively as the water enters homes?
Recommendation 4.15: The EPA should direct additional research to determine the persistence of pathogens, chemical contaminants, and other toxic materials in public water supplies in the presence of residual chlorine.
Recommendation 4.16: NIST and industry associations should examine the possibility of sensor systems that would protect the public water supply. They should also address the question of whether protection is ultimately best carried out at the water-treatment facility or at the tap (using filters or other means of purification).
In addition to the potential threat of contamination, water-supply systems are vulnerable to physical damage that could easily lead to disruption of service.
While not necessarily catastrophic, this disruption could have serious effects on the economy and on public confidence. The systems need to be highly redundant so that failure of one or more components does not lead to a major disruption. Communities should develop plans for backup, recovery, and repair of intentionally damaged water systems and for provision of emergency water supplies.
Recommendation 4.17: The EPA should convene panels of experts to assess vulnerabilities and recommend corrective actions for the various components of water supply systems. These assessments should be done with the maximum possible cooperation from industry.
RESPONDING TO ATTACKS
Supporting First Responders
The country already has large numbers of personnel who are equipped and trained (to varying extents) to provide the first response to a chemical attack. Examples include HAZMAT (hazardous materials) teams, fire and police departments, civil support teams, and military personnel (see Box 4.2). All these groups would bring critical skills in responding to an incident; the challenge is to maximize their effectiveness and provide them with the support they need to do their jobs safely. Areas in which current capabilities could be improved—protective equipment, training, coordination among various jurisdictions and agencies, predictive models, and access to reliable expertise—are briefly discussed below.
A key requirement is for equipment and procedures that protect critical personnel from being contaminated and becoming casualties themselves. Appropriate systems will undoubtedly require either compromises or multiple sets of equipment, as these systems must be designed to protect first responders not only from a wide variety of chemicals but also from a number of biological and radiological threats.
Another key requirement is to train these groups specifically to deal with chemical terrorism. Effective training includes specialized exercises by individual groups and large-scale exercises that incorporate, for example, the medical system and the National Guard. Also critical will be the development of communications networks and command protocols that establish the chains of command before an attack and allow local, state, and national groups to work together effectively. At present, the lack of strategies for coordination among the various response teams is a major problem, and the response to a chemical attack, if one were carried out today, would be inefficient and, possibly, confused.
Coordination among various jurisdictions and agencies is a serious issue. Differences in mission, style, and command structure result in conflicts among local law enforcement, health care professionals, the FBI, FEMA, and the military whenever these groups operate in the same environment. (See also Chapters
Many (if not most) cities and many industries have HAZMAT teams trained and equipped to deal with accidental spills and releases of toxic industrial chemicals. They have not been trained or equipped to deal with terrorist incidents, but chemical weapons of the types that would most plausibly be used by terrorists are not fundamentally different from the chemicals that these teams already address.
Among the first responders to chemical terrorism, fire departments can be a major resource. All fire departments have personnel who are trained and equipped to work with respirators and protective gear (as hazardous vapors are always a part of fires), and they are of course trained to deal with emergencies. The police are not routinely equipped to respond to chemical incidents per se (although they play an essential role in maintaining order). Equipping police units with protective gear is, however, a practical way of expanding the number of individuals who can actively participate in the response to a chemical incident.
Weapons of Mass Destruction Civil Support Teams from the Department of Defense are deployed around the country.1 These groups have a limited but possibly useful capability to coordinate communications among responders and to carry out chemical and biological analyses.
Another substantial capability in place is the military, including active-duty, reserve, and National Guard personnel. The military has trained and equipped for chemical warfare during the past 50 years. It maintains large supplies of relevant equipment—protective suits, prophylactics, and medical countermeasures against nerve and blister agents. These assets are geared, however, to wars on foreign battlefields. An important issue is to understand how to use this capability in time of need inside the continental United States.
12 and 13.) In some chemical attacks, still other agencies would be involved (e.g., the USDA for attacks on the food supply and the EPA where decontamination is required). The most efficient mechanism for working through the usual conflicts among these organizations, and for rendering workable the laws and regulations under which they operate, is to carry out field exercises—simulations of real attacks—with all those entities that would be likely to participate. Differences should be settled before an event rather than after it.
Exercises and protocols can only be taken so far, however; it is impossible to envision and plan for all possible scenarios. To minimize the consequences of any attack, it is thus essential that the person (or persons) in charge of the response be able to readily access as much information as possible and to commu-
nicate resulting decisions to the right parties as rapidly as possible. If a tank car filled with chlorine has been blown open in a switching yard, what areas of the city are at risk? If there has been a sarin attack on an office building, how should the nerve agent best be kept localized? There are many factors to consider in determining the answers to these questions; explicit, one-size-fits-all solutions will not always be appropriate. The incident commander must have the ability to adapt in real time.
One important need is for software that will allow the commander to predict the movement of chemical agents—through the city’s atmosphere, in buildings, or in tunnel systems. Work on this type of tool, especially in the area of atmospheric modeling, is proceeding, but there are at present several competing models whose results are often in disagreement. Further R&D is clearly needed to resolve these anomalies or develop more dependable alternatives.
Another important source of information for incident commanders is fast access to reliable expertise (sometimes called “reachback”). Chemistry is technically complex, and first responders and their leaders cannot be expected to know the details for all possible chemical attacks. They must be able to consult, in real time, with experts familiar with the characteristics of the weapons. A panel (or panels) of such experts should be formed immediately to improve the likelihood that they will be available when needed and to ensure that appropriate channels for effective communication are established. (Industrial risk and industrial safety groups might be a good source of experts.) The Marine Corps has worked with such a reachback group—the Chemical/Biological Incident Response Force (CBIRF)—and this experience might provide a starting point for the design of groups to serve incident commanders and first responders. Even without a terrorist event, these groups could be of use—there are unfortunately enough chemical spills and accidents nationally for responders to benefit from the group’s input (and give it real opportunities to practice).
Recommendation 4.18: FEMA, with technical support from the Defense Threat Reduction Agency (DTRA), should be tasked with developing a communications structure for ensuring that response teams have quick access to reliable expertise when managing chemical incidents. In addition, these agencies should establish and test a prototype panel of experts.
Preparing for Treatment of Victims: Improving the Capabilities of the Medical System and the Treatment Options
The United States has a very competent medical system, but it is not currently prepared to deal with chemical attacks (especially with nerve or blister agents). Two areas in particular are in need of improvement: (1) the inability of the medical system to handle a large number of casualties from a chemical attack and (2) the lack of experience on the part of the nation’s health professionals in
dealing with casualties of this type, together with the lack of optimized treatment protocols and the possibility that there are no appropriate drugs.
To enable the medical system to respond to a large number of chemical casualties, several issues must be addressed. First, casualties still contaminated with chemical agents are likely to present at hospitals. To avoid contaminating medical personnel and facilities as well, there must be accepted protocols for decontaminating and handling these casualties. Second, in an attack on a population center, experience suggests that for every legitimate patient presenting at the hospital, between 100 and 1,000 “worried well” will also arrive, looking for reassurance. Hospitals have no capability to manage crowds or to triage large numbers of anxious people. Third, the U.S. hospital system—in the interests of efficiency—has slimmed down to the point that there is essentially no capacity for surges in demand for medical care. Thus there are not enough beds, medical supplies, and respirators to deal with any substantial number of terrorist-event casualties.
Recognizing that the medical system is ill prepared to handle a massive influx of chemical casualties is not the same as knowing how to prepare for such an event. A great deal of work can be done with computer modeling and tabletop exercises, but only through field exercises will the real weaknesses in the system be discovered. Carrying out exercises of this type is expensive, however, and can raise the public’s level of anxiety. Deciding on the best course to pursue in preparing for the possibility of mass casualties is an issue of policy, but resolving the technical details requires a balance between paper or computer exercises and checks of reality.
Recommendation 4.19: With the collaboration of hospitals and medical associations, FEMA should lead a careful systems analysis of needs—covering doctors, facilities, supplies, and equipment—for responding to plausible large-scale chemical attacks. This analysis should be used as the basis for planning the acquisition, storage, and distribution of resources in preparation for such attacks.
Recommendation 4.20: The federal government should work with the private sector to develop plans to provide surge capacity and to conduct exercises with the full participation of the medical system.
Recommendation 4.21: The federal government should provide leadership in developing strategies for training medical personnel in appropriate responses to chemical injuries and for stockpiling associated medical supplies.
Treatments for chemical casualties have come primarily from military medicine and are intended to preserve soldier function. Whether these protocols are optimal for civilian casualties has not been resolved or even carefully considered. The issue of long-term damage to the central nervous system is particularly
important. The carcinogenicity of blister agents is a second concern, and each of the other potential agents raises its own set of concerns. Understanding the pathogenesis of these chemical weapons is an important step in developing rational protocols for treatment of the casualties they produce.
Research in this area is complicated by the fact that it is not possible to work with human patients, and the most relevant tests are carried out with higher primates (which are both expensive and widely protected). Developing cellular models, or improved whole-animal models using rodents, will be an important part of this program.
Recommendation 4.22: Under the guidance of the NIH, there should be a program to develop improved treatments for injuries that result from exposures to chemical agents.
This program should have both an applied and a fundamental aspect: It should optimize existing protocols, using the most plausible threats, and it should increase our understanding of the general mechanisms of injury on exposure to toxic chemicals. The program should address treatment for both acute and chronic injury, and it should consider countermeasures and protective measures that embrace the full spectrum of threats. Because of the long time required to develop countermeasures, we should start now on important classes of weapons, even if they are not yet known to be ready for deployment.
The system used for developing drugs in the United States will require modification in order to support the development of treatments for chemical attacks. Several problems will have to be addressed:
The markets are too small (unless dual-use applications can be developed) to make a serious effort by the pharmaceutical industry worthwhile.
The system on which FDA clearance is based—the testing of new drugs in humans in carefully controlled trials—cannot be used, as these trials have no benefit for the subjects that would be involved.
The best surrogates for humans in many studies—higher primates—are very carefully protected.
Many of the chemical agents involved—especially nerve and blister agents—are difficult (or illegal) to use in universities.
The problems of carrying out this kind of research, and of clearing new drugs for use under appropriate circumstances, may require exceptions from current laws and regulations, along with indemnification of suppliers of materials in case of adverse reactions in humans. The FDA is well aware of these problems with regard to biological attacks, and it is trying to develop a suitable system for drugs that would be used in treating the resulting casualties; similar strategies will be applicable for drugs relevant to chemical attacks.
A STRATEGY TO DEVELOP ECONOMICALLY VIABLE COUNTERTERRORISM TECHNOLOGIES
Technologically speaking, the United States is enormously inventive, but without commercialization, the deployment of technological advances is not very likely. To develop the products and systems needed to protect vital systems and respond to attacks, probably the most successful strategy will be to focus explicitly on technologies that have broader commercial applications as well as value for counterterrorism efforts. (This topic is discussed further in Chapter 13.) For example, some sensor technologies can be developed for more general or larger markets (biomedicine, environmental monitoring, food safety) while also being useful for emergency response and incident management.
A similar trend, driven by the dual goals of environmental quality and economic efficiency, is already moving the chemical industry in new directions. Sustainable (green) chemistry—the design, manufacture, and use of efficient, effective, safe, and environmentally benign chemical processes and products—is now receiving widespread industry attention, though the need for considerable improvement remains. Government, academia, and industry should strive to identify research directions that could lead to safer, intrinsically secure, economically viable chemical processes and procedures that are valuable for our long-term sustainability. Such efforts also have a benefit for our nation’s counterterrorism efforts as well: If we make fewer toxic products, use milder manufacturing conditions, and produce less toxic waste, we reduce the opportunities for terrorists.
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RECOMMENDED READING ON FOOD SAFETY
Hartman, N.F. 1997. “Reducing Food Poisoning Deaths,” Engineering & Technology for a Sustainable World, Vol. 4, pp. 11-12.
Holcomb, D.L., M.A. Smith, G.O. Ware, Y.-C. Hung, R.E. Brackett, and M.P. Doyle. 1999. “Comparison of Six Dose-Response Models for Use with Food-borne Pathogens,” Risk Analysis, Vol. 19, pp. 1091-1100.
Institute of Medicine. 2001. Food Safety Policy, Science, and Risk Assessment: Strengthening the Connection, Workshop Proceedings, National Academy Press, Washington, D.C.
Liu. S., J.-C. Huang, and G.L. Brown. 1998. “Information and Risk Perception: A Dynamic Adjustment Process,” Risk Analysis, Vol. 18, pp. 689-699.
Loaharanu, P. 2001. “Rising Calls for Food Safety: Radiation Technology Becomes a Timely Answer,” IAEA Bulletin, Vol. 43, pp. 37-42.
National Research Council. 1998. Ensuring Safe Food: From Production to Consumption, National Academy Press, Washington, D.C.
Otero, R., and J.O. Grimalt. 1994. “Organochlorine Compounds in Foodstuffs Produced near a Chlorinated Organic Solvent Factory,” Toxicological and Environmental Chemistry, Vol. 46, pp. 61-72.
Strongin, Robin J. 2002. “How Vulnerable Is the Nation’s Food Supply? Linking Food Safety and Food Security,” National Health Policy Forum, NHPF Issue Brief No. 773. George Washington University, Washington, D.C., May 17.
Teixiera, A. 1994. “Connectivity Critically Important in Engineering a Safe Food System,” Resource, Vol. 1, pp. 12-14.