Exposure Science for Terrorist Attacks and Theaters of Military Conflict: Minimizing Contact with Toxicants

Abstract

The strategies for protecting our deployed U.S. Forces are outlined in National Research Council documents published in 1999–2000. This article summarizes experiences and information gathered and interpreted regarding population and rescue workers’ exposures in the aftermath of the 2001 World Trade Center attacks, with the aim to provide insights on issues related to military deployment to locations with hazardous agents. Issues coveted include phases of exposure, materials of concern, detection equipment, and personal protection equipment. The focus is on human exposure issues, which are primarily associated with strategies 1 through 3 of the National Research Council’s report entitled “Protecting Those Who Serve: Strategies to Protect the Health of Deployed U.S. Forces”. Contact and duration of contact with hazardous substances are critical areas of concern, which require prevention and intervention procedures and protocols to reduce the incidence of acute and long-term health outcomes.

INTRODUCTION

The refinement of concepts and procedures used to protect troops during combat has been an. enduring and challenging task of the U.S. armed services since the militia was formed in the 18th century. As time has passed, the nature of environmental threats to the Armed Forces has evolved and expanded along with changes in the conduct and scope of military actions. As a result, force protection has become more complicated from the points of view of prevention, interdiction, response, and control of casualties, to include potential exposure to toxicants. Chemical, radiological, and biological weapons have been readily available as part of military arsenals for over 60 years. Each has been used during military campaigns or individual combat actions. In specific incidences, radiological and chemical toxicants have been used as weapons by various countries against small and large segments of the general population. In addition to potential and actual exposure to hazardous materials within combat zones, there are a number of additional potential human exposure issues raised by the presence of hazardous materials during both combat and non-combat situations. Examples include the aftermath of catastrophes such as .the September 11, 2001 (9/11/2001) World Trade Center (WTC) collapse, and the capture and protection of high value facilities and operations, e.g., chemical plants.

EXPOSURE SCIENCE

To provide a baseline for a discussion regarding toxicant exposures, one first needs to define exposure and the applied science that may provide technologies that can protect workers and the public health. Human exposure is defined as the existence of a person and a toxicant in the same place and time, and the occurrence of contact between them.¹ The level of exposure is dependent upon the concentration and duration of contact. However, to be clinically meaningful, the exposure must also be coupled to a biologically relevant duration of contact, specific to a given disease.²

The general field of Exposure Science is defined, as published in the Journal of Exposure Science and Environmental Epidemiology by Dana Barr, as follows: The study of human contact with chemical, physical or biological agents occurring in their environments, and advances [in] knowledge of the mechanisms and dynamics of events either causing or preventing adverse health outcomes.³

The activities of exposure science link many components of the environmental health continuum, and these are illustrated in Figure 1.

FIGURE 1.

Activities of exposure science from emissions of contaminants to health effects, with points of action for strategies to protect deployed U.S. Forces.²

MINIMIZATION OF DEPLOYED TROOP EXPOSURES

In the National Research Council (NRC) report entitled, “Protecting Those Who Serve: Strategies to Protect the Health of Deployed U.S. Forces,” six important strategies were presented, each based upon the content of previous reports.⁴ These are:

1. Use a systematic process to prospectively evaluate non-battle-related risks associated with the activities and settings of deployment.

2. Collect and manage environmental data and personnel location, biological samples, and activity data to facilitate analysis of deployment exposures and to support clinical care and public health activities.

3. Develop the risk assessment, risk management, and risk communication skills of military leaders at all levels.

4. Accelerate implementation of a health surveillance system that spans the service life cycle and that continues after separation from the service.

5. Implement strategies to address medically unexplained symptoms in populations that have deployed.

6. Implement a joint computerized patient record and other automated record keeping that meets information needs of those involved with individual care and military public health.

Based upon the scope of this manuscript, strategy recommendations 1, 2, and 3 are the focus of the following discussion, but each of the above are necessary to improve the short-term and long-term healths of the deployed U.S. troops. Using the above strategies as a conceptual framework, the overall goal is minimization or prevention of contact with hazardous materials in a given situation. Further, as outlined above and in contrast to many formulations of community-based risk assessments, the first strategy indicates defining the activities and settings that may he encountered, above and beyond those related to battle. Thus, the strategy’s first goal is to accurately define situations that may lead to contact with toxicants. This is the correct approach to providing procedures and training that are focused on avoiding non-combat risk associated with toxicants exposure. Figure 1 illustrates specific locations along a continuum where each of the above strategies can be implemented to either reduce exposure or, at very least, understand the potential consequences of exposure.

The implementation of programs to achieve the goals of each strategy, however, is complicated by the nature, timing, and potential severity of each potential threat, both during and after combat. In the case of combat actions, threats are often direct (immediate) and may come without warning. Post-combat, in the protection of high value assets, for example, threats can be immediate or arise over time. A key to success in either case is the rapidity with which individuals, including exposure scientists and occupational hygienists, can identify the source(s) and agent(s) of concern, characterize exposure pathways, and implement controls. Thus, training in exposure science is a needed specialization within the Armed Forces.

In both combat and non-combat situations, current and as yet undeveloped detection and protection systems are required to reduce the possibilities of contact with a toxicant or to determine the magnitude of contamination before entry into or stabilizing a captured area. Currently, most toxicant detection systems are bulky. They can be deployed on a variety of platforms (e.g., ground vehicles and planes); however, the near-field exposure issues for various types of troop detachments, e.g., platoons of about 40 people, require miniaturized and continuous sensing devices. There is research on such devices, but more needs to be done to harden equipment against the extreme conditions encountered during and after battle. Once collected and validated, data can be stored, transmitted, and used to evaluate the severity of the problems associated with a particular situation.

One problem that may arise is providing criteria on how much data to store and for how long? The relevant question is this: How quickly can information be interpreted to minimize injury or death? In a direct impact situation, one cannot easily deploy monitoring systems during military action, often because of their weight, and the use of miniaturized units for the detection of multiple agents on a real time basis may not be possible. Mobile monitoring and analysis vans could be helpful, but they may be targets during an action. Drone monitoring systems capable of operating in the line of fire should be considered for development. In exposure situations encountered after the completion of an engagement in a war zone, deployed units may have more time to assess the situation, but the need to react quickly and deploy monitors to prevent and characterize exposures remains.

As noted in the NRC report, post-event issues need much attention since the nature of the deployment often changes from one of aggression to one of protection and re-entry.⁴ For such situations, troops may be deployed specifically to guard a unit or a facility from further hostile actions, or contractors who may be completing non-combat-related activities. Since this is a primary mission of the troops, it is important to realize that basic issues of occupational and environmental health and safety need more attention, as a basic component of troop survival. Thus, it is essential to train deployed troops and pre-position exposure science and occupational health personnel for potential post-action toxicant exposure situations. This will increase the probability that adequate personal protection and administrative controls are made available to prevent exposures to toxicants. In each of the NRC reports in the series, there are well-defined steps and activities that provide an overview of major components of the issues.^4–7 The question may arise as to whether or not such comprehensive steps are correct. They are. During the course of both combat and non-combat activities, troops may not be in a position to do large-scale planning, and will probably be confronted by surprises. The pre-positioning of tools and protocols for entry and sustainability in the aftermath of an engagement is essential for success. However, there are still examples where this has not occurred in a systematic fashion, including the hexavalent chromium piles at the Qarmat Ali Industrial Water Treatment Plant, Basra, Iraq (Review of the U.S. Army Center for Health Promotion and Preventive Medicine Assessment of Sodium Bichromate Exposure at Qarmat Ali Water Treatment Plant. Washington, DC, Defense Health Board. Available at http://www.health.mil/dhb/downloads/2008_DEC_l/05_%20 Halperin_QARMAT%20ALI%20DHB%20MTG%2012-15-08.pdf, December 15, 2008; accessed January 21, 2011), and troop encampments that were downwind of the Balad burn pit (Kennedy K: Balad burn pit harmed troops living 1 mile away. Army Times, January 23, 2010. Available at http://www.burnpitlawsuit.com/media/ArmyTimes_Balad-burn-pit-harmed-troops-living-1-mile-away_1-23-10.pdf, accessed January 21, 2011). Each indicates the need for a thorough review of procedures and that the above strategies in noncombat situations.

THE WTC EXPERIENCE

In “Dust: The Inside Story of the September 11th Aftermath,” a number of points were discussed and examined regarding WTC exposures.⁸ Contained in the book is information garnered from government reports, scientific manuscripts, and observations.^8–23 The author’s conclusions were that the country was not well prepared to respond efficiently to the immediate environmental and occupational health issues that arose in the aftermath of the WTC collapse. There was no one particular group to fault, even though many agencies and organizations were involved from different branches of government, including the military, and the private sector. The occupational and environmental exposure lessons derived from the events of 9/11/2001 were numerous, and could be evaluated in the context of the NRC Deployed Forces Strategies and implementation framework.⁴ They would be associated with NRC strategies 1,2, and 3.⁴ From the WTC aftermath, lessons have been learned; some lessons still need to be implemented to protect the public, and especially response teams.^11,12,24,25 The following are major needs identified in the book that relate to exposure response.⁸ Included are the specific NRC non-combat deployed troop health protection strategies to which they relate:

1. Need for improved portable and flexible emergency response platform and personal monitors (strategy 2).

2. Need for strategies to ensure that chemical, physical, and biological samples can be quickly collected and analyzed, and sensor data quickly processed on toxicants (strategies 2 and 3).

3. Need for measurement and detection systems that can be quickly deployed on site or available in strategic locations (strategies 1 and 2).

4. Need for accurate information on the processes and toxicants stored at facilities and debris that is disposed of post-engagement (strategy 1).

5. Need for short-term exposure standards and associated methods for detection in the concentration ranges of concern (strategy 3).

6. Need for safe indoor and outdoor clean-up protocols (strategy 3).

7. Design and implementation of highly flexible respiratory protection equipment with communication capabilities and the availability of personal protective equipment for different routes of contact and exposure (strategies 2and 3).

8. Need to have prepositional situational awareness of potential toxicant contacts and severity of outcomes for an inventory of possible situations (strategy 1).⁴

Many of these lessons were outlined as points of information and need in the NRC 2000 Deployed U.S. Forces report, and should be followed up with detailed protocols and criteria.⁴ However, even the military components did not appear to deal effectively with these issues following the attack on the WTC. Possible reasons for this are the rarity of such catastrophic situations, especially on U.S. soil, and the difficulty in obtaining an overview of the major toxicant exposure and health issues in a very short period of time. Without accurate data on the materials that might have been of concern and the levels and duration of exposure during the events that followed the WTC collapse, it was not possible to obtain an informed understanding of the situation regarding acute exposures and health protection responses. Recognition of acute health effects occurred about 1 week after the WTC collapse, when the “WTC cough” was first observed among firefighters and others who arrived at the disaster site before and immediately after the attack.¹⁶ The identification of victims, in this case first responders, is a typical method for defining a common exposure, but it is not an optimal way to minimize the number of post-event casualties. It is usually indicative of a general lack of information regarding the nature of the toxicants being emitted during an evolving situation. In the case of the aftermath of a terrorist incident like the WTC attack, and in most instances of non-combat deployment, it is doubtful that we will ever have the resources on hand and readily available to definitively characterize the agent or agents of eventual concern immediately after an event. This would include exposures to toxicants during the first minutes to hours after their emission.

Most monitoring devices are expensive, and more importantly, require maintenance and periodic calibration to remain of value. There are systems that operate continuously, and some are currently deployed at strategic locations indoors and outdoors in major U.S. cities, and in mobile units. However, there is no simple way to predict the target of an attack. Further, having devices to detect biological, physical, and chemical agents on call in major cities, and other high target locations, is cost-prohibitive.⁸ The best that can be done is having personnel and monitoring platforms available at strategic locations across the country. The mission, then, is to respond as quickly as possible to an exposure event. However, information gathering could still range from minutes to many hours after an event, depending on the location of the event and the closest monitoring equipment and personnel. The full range of tools can be simple or complex in nature, but to achieve the goals of NRC Strategies 1 through 3, they need to address the components shown in Figure 2. Each tool or activity is needed for observation, measurement, and control of potential exposures.

FIGURE 2.

Elements that must be considered in developing information gathering tools and exposure metrics for deployed U.S. Forces.

WTC LESSONS AND NRC’S TROOP PROTECTION STRATEGIES 1,2, AND 3

Strategy 1

The collapse and disintegration of the WTC towers into dust and the associated fires was an unanticipated aftermath of the terrorist attack. However, the earlier 1993 terrorist attack on the WTC did provide guidance for evacuation procedures, and those procedures likely saved lives. Further, the nature of the collapse, and disintegration of all building materials and contents into dust, was not even a remote consideration as potential components of human exposure. The lesson that has been learned is this: Do not assume anything other than the worst. The collapse of modern buildings yields complex exposure situations because of the nature of the construction and materials. The toxicant profile resulting from the collapse of modern buildings is, for example, very different from that of older buildings or of those in many developing countries. Therefore, if National Guard or other military units are to be deployed to guard such a site of destruction, there needs to be training as to the hazards for health and injury around such a location. Also, during intervention, the leadership must define what protective equipment needs to be worn before entry into the area. An inventory of exposure conditions was warranted but unavailable at the WTC. Thus, use of proper respiratory protection was not strictly enforced. A series of training exercises for situations such as the WTC collapse could identify gaps in knowledge and the types of protective gear needed at a site.

Strategy 2

The WTC collapse clearly illustrated that an integrated approach to the collection of data on dust and smoke was needed. Data were collected initially for the presence of radiation and selected hazardous substances. Furthermore, inventories of potential sources of toxic chemicals (e.g., chlorofluorocarbons) were made. The New York Fire Department (NYFD) also took biological samples from firefighters to examine levels of gases and other materials that may have been inhaled during activities at ground zero. The latter effort proved to be important in discounting the significance of mercury exposures at ground zero.¹⁶ Thus, management of two concerns for noncombatant situations had partial successes in the chaos.

Initial assessments of the potential hazards that may have led to exposure were crippled at the WTC because of the lack of instrumentation. Two of the most apparent reasons for this were the lack of portable devices to collect particles and gaseous material in dusty situations, and the lack of understanding that the immediate concern was short-term exposures to dust and not the potential long-term effects caused by asbestos exposure or fine particles. The mindset at the time was focused on low-level exposure and long-term disease outcomes. In fact, we have drifted back to that position over the past few years, even though the NRC has continued the important work of developing Acute Exposure Guidelines for highly toxic substances, which will be of benefit in non-combat deployed U.S. forces situations.²⁶ These will also enhance the selection of the tools related to the capabilities highlighted in Figure 2 that are appropriate for a particular situation or suite of toxicants.

There have been improvements in the types of monitors that can be put on various platforms for use, but I still have not seen updated total particulate matter mass samplers which, in retrospect, would have been capable of quantifying a major issue of concern. Training in acute exposure intervention and prevention is still needed in civilian situations, and should be a priority for training of military personnel for combat and non-combat activities (NRC Recommendation 2 in Strategy 2).⁴ In non-combat and combat situations, leaders of deployed forces should follow the NYFD example. Biological markers may not be a comprehensive marker of exposure, but in an acute exposure situation they can give valuable information on exposure to a wide variety of potential toxicants. The corollary is an absolute need for a field laboratory to process these samples quickly. Biomarkers, however cannot take the place of sensors for real time understanding of likely hazardous agents. Biological markers are useful only after exposure may have occurred.

Strategy 3

Risk management, assessment, and communication are valuable evaluation tools. The effectiveness of each is dependent upon the accuracy of information and the speed at which advice can be effectively transferred. Within the WTC aftermath, the initial messaging was at best confusing and many times conflicting in depth and level of accuracy. There were many reasons: providing reassurance with limited information, poor data on the hazards and time course of acute exposures, multiple entities being in charge, and an inability to say, “We do not know, yet.” All the above contributed to the initial chaos. In a military action or post-battle exposure event, there needs to be clear and effective lines of communication, members of a team that can interpret data, and officers who will understand the meaning of the interpreted data. Most important are the professionals who can provide guidance and recommendations on how to proceed. In the aftermath of the WTC collapse, the messaging improved over time.

DEPLOYED TROOP CONTACT WITH TOXICANTS

Theaters of action can yield a number of situations that involve direct troop encounters with toxicants. However, they will be finite in number, and there are specific types of materials that can be surmised or assumed to be highly likely toxicants of concern. Some toxicants and situations will demand data be collected immediately, whereas others will allow a reasonable time for assessment and implementation of protective measures. Concurrently, the location and number of military forces potentially in harm’s way will be finite, and there will be some documentation about their locations in space and time. Thus, single or multiple sampling and monitoring platforms can be pre-positioned and, if necessary, be made available to military units for use during a specific deployment. The response to an event or detection of an event can be faster based upon the availability of, and proximity of, monitoring equipment to deployed personnel. Future detection platforms should include drones with detection devices in the theater of operations during an engagement with an enemy.

A more difficult task for environmental and occupational exposure specialists is the post-action security tasks that may require troop deployment in areas such as oil fields, chemical plants, contraband destruction (incineration) sites, and power plants. Of further importance is the fact that not all countries have the same environmental and occupational regulations as the United States, and some may have virtually none. Thus, one may assume nothing regarding safety, and one must be alert for the need to wear personal protective equipment and enforce administrative controls to safely guard such facilities. Consequently, monitoring equipment needs to be available, and surveys conducted to characterize the potential exposures that may be encountered before establishing permanent security or conducting other similar activities. Subsequently, monitoring and surveillance need to be formalized for the deployed troops who guard contractors and others during the destruction of contraband and other operations relating to critical infrastructure and facilities. Thus, the protection of the deployed troops would include information required for achieving risk minimization to prevent contacts at the points along the continuum in Figure 1. In addition, it must be remembered that during the re-entry and restoration of a facility the nature of the hazards can change, which indicates the need for regular communication among the individual contractors and Armed Forces units to ensure protective measures are adequate for the conditions encountered as time passes and conditions change. In the articles by Lioy et al about the aftermath of the WTC disaster, it was shown that the nature of the exposures and those potentially exposed changed over time at and around ground zero.^9,10. The evolving situation was one of many different issues that lead to the lack of information about what responders and others were being exposed to at various points in time and locations. This tended to confuse the interpretation of messages, and in some cases led to overinterpretation or misinterpretation of the potential acute and long-term health outcomes caused by exposures at various points in time. For situations involving deployed forces that are designated to guard a facility or area with identified or suspected hazards, it is essential to provide current information on the need for and the level of protective equipment or administrative controls during all phases of re-entry, restoration, and rehabitation.

CONCLUSIONS

The NRC documents available on protecting our deployed troops provide a good management framework for protection of health and safety during actions and activities that can lead to contact with toxicants.^4–7 This said, it is important to develop and test a series of protocols that can ensure that monitoring and analytical capabilities are in the field at critical times that provide real time or quasi-real time data and information on suspected or known toxicants. The platforms that should be available for use at a facility may include both personal sensors and portable monitors mounted in a vehicle. A variety of samplers should be tested, including those which measure physical, chemical, and biological materials. Thus, as troops are deployed in an area, either during combat or after combat activity, there will be some reasonable probability that equipment is available to detect toxicants, and that, if measured, strategies and personal protection devices are available to reduce casualties during or after the hostile action. There are some devices currently available, especially for use during hostile action, but these need to be systematically introduced as part of a series of practical protocols that one can use to minimize the reoccurrence of problems generated by materials like Agent Orange.²⁷ However, such devices may not preclude situations like the Gulf War syndrome, which appeared to be a multiple chemical sensitivity among a fraction of the deployed troops.²⁸ It remains to be determined how such low level contacts and exposures can be easily quantified on a battlefield or in a staging area, but the Acute Exposure Guidelines do provide a baseline for development of exposure monitors and entry protocols.