All Findings and Recommendations
Naturally occurring infectious-disease hazards provide much information that is useful for biodefense consequence management planning, but weaponized biological agents could pose special threats that are distinct from those attributable to naturally occurring hazards, especially when it comes to decontamination.
Decontamination decisions and plans should consider the natural characteristics of a specific pathogen and the weaponization characteristics of that agent. Weaponized agents can vary in infectivity and virulence as a result of formulation, and the presence of a natural background of weaponized agents (such as weaponized B. anthracis) is unlikely in indoor public facilities. Given the uncertainties in the characteristics of the weaponized agents, it is impossible to establish acceptable thresholds below which exposure to such weaponized agents would pose zero risk.
Determining acceptable risk is a complex issue: Willingness to accept risk varies from person to person, from situation to situation, and from culture to culture. Managing risk also is complex: Different people have different ideas about how much responsibility the government or the owners and operators of public facilities and lands have to limit public exposure to risk. Those issues have been considered in many situations, and many policy-making lessons can be learned from events involving Superfund and the U.S. Department of Energy.
In contemplating how to respond to potential biological attacks, authorities should base their plans on lessons from the experiences of others who have dealt with decontamination issues in the broadest sense; they should not consider their charge a completely novel task. Decision making about a facility contaminated as the result of a biological attack should be mindful of the critical policy dimensions of the biological quality of the hazard, the public nature of the building, the public’s perception of an attack, and the event’s national security implications.
If safety-related standards and protocols are devised and implemented behind closed doors, without the consent or input of affected and interested parties, those standards are likely to be questioned or rejected outright. Lack of transparency for policy decisions that directly affect public health—even in the context of a proclaimed national security interest—can severely erode public confidence. The establishment of a formal planning procedure that involves relevant stakeholders before an event should expedite the response and confer legitimacy for decisions made during and after decontamination.
Representatives of affected parties should be involved in risk management decision making, and they should participate in the technical discussions needed to make decisions. Engaging the people whose well-being is most at stake helps ensure their greater confidence in the outcome of risk-based decisions. Those who provide the technical information should be independent experts who are free of conflicts of interest, so that they can give the highest priority to protecting public health. Stakeholder involvement in risk assessment and management provides valuable returns: local knowledge that can contribute to a more robust definition of the danger, greater public confidence in scientific tools that support public policy, and more widespread acceptance of the legitimacy of the results.
People and microorganisms cohabit the world; their interactions sometimes result in human disease. Nonetheless, in settings where people risk exposure to pathogens (laboratories, hospitals), biological safety policies can protect against human disease. Decontamination is not a standalone activity, but part of a larger set of controls over dangerous microorganisms and their potential health effects. The domestic institution that routinely dealt with weaponized pathogens—the U.S. Army Biological Warfare Laboratories—developed a comprehensive set of biological safety programs to control those pathogens. Protective measures ranged from preemptive vaccination to medical monitoring and treatment for inadvertent exposures.
Integrated protection for human health is the most prudent policy in the context of a facility contaminated as the result of a biological attack. After a facility has been decontaminated, some type of medical monitoring is critical to ensure confidence that a facility is safe, and the purpose and outcome of medical monitoring should be made transparent to affected parties. In the event of any incident in the future, a centralized and sustained effort should be organized to track the health of those exposed, or potentially exposed, to pathogens.
Acceptability is not a technical concept. It is a values concept. It is, therefore, best constructed through an analytical and deliberative process that involves key stakeholders in a potentially harmful situation. Without trust, acceptability is difficult to achieve. Effective leadership in dangerous situations is based on openness and honesty, even when bad news must be conveyed. Transparency in decision making can contribute substantially to ensuring the acceptability of risk. Panic is rare in disasters, and it is an unhelpful idea for explaining how people respond to frightening situations and information. After the 2001 anthrax attacks, decision makers sometimes relied on assumptions that later proved unfounded; their subsequent actions resulted in significant problems with communicating the degree of risk involved to the stakeholders.
Risk managers who face potential contamination should assume that the problem could be worse than they initially think. In remediation projects, the public should be seen as an asset, not a liability, and information should be made available widely. Indeed, the public should participate actively in decision making in the aftermath of an attack. Following the lead of previous work by the National Academies, the committee recommends that an analytical deliberative process be used to determine appropriate approaches for cleanup.
Relevant data from the sites contaminated in 2001 were not shared with all necessary parties, partly because of the differing goals and objectives of law enforcement and public health agencies. Lack of data sharing can compromise health in the aftermath of a biological attack.
Agencies and organizations entrusted with data relevant to public health should make every effort to share this information. Cooperation is the key to decreasing public anxiety, and agreements, such as the one signed by the New York City Department of Health and relevant law enforcement agencies, should be in place
to protect public health and safety by allowing the process of forensic evidence collection and decontamination to proceed unimpeded by one another.
The QMRA process, developed over the past 20 years, has been used to inform decision making about events involving microbial hazards that affect food safety, drinking-water quality, and the use of isolation rooms in hospitals.
A risk assessment approach should be adopted as one component of decision making for determining the adequacy of decontamination efforts after a release or suspected release of a biological contaminant.
Thorough risk analysis requires critical information about each variable. This information is weak for certain variables when one considers agents that might be used in a biological attack.
More dose–response and sampling source data are needed to inform a practical, as opposed to a theoretical, risk analysis for any given biological attack.
Detailed characterization (including screening for known threat agents, genetically modified and emerging threat organisms) of a suspected biological pathogen is required for proper analysis and to inform decision making.
Research should be conducted to develop a characterization system that can inexpensively identify, or approximately characterize, all potential threat agents including genetically modified and emerging threat agents.
Identifying and characterizing the properties of an organism (or organisms), and the amount and extent of its concentration at the time cleanup begins, are critical to making decisions about response options.
Characterizing the contaminating agent or agents should be done before selecting the approach for large-scale remediation. The remediation approach chosen should be one that can adequately destroy (or remove) the amount of agent present at the start of the procedure.
The earlier contamination is detected the easier it will be to restrict the area of contamination and the number of individuals who will be exposed. In the case of the 2001 anthrax letter mailings, the event first came to light through the observations of an astute physician. Different monitoring systems—environmental (e.g., Biowatch) and medical (e.g., syndromic surveillance) in nature—have since been put in place with the hope of obtaining the earliest possible indicator regarding the release of a biological agent.
Existing environmental monitoring systems and syndromic surveillance systems need to be evaluated for their abilities to provide information that can be used to detect and to limit the spread of biothreat agents in a cost effective manner. If those systems prove to be effective, they could be deployed in public facilities that may be likely targets for attacks.
Biological agents can spread beyond their point of initial release in air-handling systems, through the reaerosolization of contaminants from floors and other surfaces by foot traffic or air currents, and by adhesion to people or their clothing. Those factors can result in widespread dispersal of biological contaminants within a building and into transportation and transit vehicles, homes, and other sites.
An extensive survey should be done to determine the extent to which biological contamination has spread. (Further guidance on surveying and sampling can be found in Chapter 9.)
Indoor air-handling systems can redistribute biological agents by carrying airborne contaminants throughout buildings and outdoors. However, if appropriate actions are taken, air-handling systems also can be used to confine contaminants and reduce the effects of contamination.
Building operators should act now to gain a thorough understanding of how air flow occurs in their buildings under normal operating conditions. They also should examine the potential adverse or beneficial effects of a shutdown on the spread of airborne contaminants so that appropriate actions could be taken to minimize the dispersal of contaminants if the release of a biological agent is identified.
Architects, construction engineers, ventilation engineers, facility operators, and other professionals involved with building design, construction, and operation have an inadequate understanding of how the built environment affects occupants.
The professions related to the building industry and facility management should be better educated on the nature of their vulnerability to weaponized agents so they will be prepared to respond to an act of bioterrorism. Professional societies (such as the Building Owners & Managers Association, and the International Facility Management Association), state and federal agencies, and academic institutions should fund and participate in efforts to increase understanding of those issues through education and training.
The concept of a “threshold” below which no risk to a population exists for a microbial dose response is not supported by currently available data. Nonthreshold dose–response models present a more cautious approach that has been found appropriate for describing human response to a diversity of infectious agents via ingestion, inhalation, and other routes of exposure. Dose–response data for most of the pathogens of concern (biological agents) are incomplete or have not been critically analyzed in the open literature.
Available dose–response data for pathogens of concern should be analyzed by non-threshold dose–response models.
Because minimal publicly available data exist on which to base human dose–response relationships for the critical pathogens, animal data must be used. However, our understanding of interspecies extrapolation of dose–response relationships for infectious agents from animals to humans is low.
Targeted research to help inform decision making on extrapolation of dose–response data between species for the pathogens of concern should be conducted. That research might use several species of organisms or use animal and human tissues to reach conclusions that are relevant for human exposures. With the increasing difficulty of performing primate studies, it will become more important to develop in vitro techniques that can be used to develop dose–response information.
General Centers for Disease Control and Prevention (CDC) sampling guidance exists for Bacillus anthracis spores, but there is no official guidance for the collection of vegetative B. anthracis, plague bacteria, nor smallpox virions.
Sampling protocols must be appropriate to the threat. Sampling for B. anthracis spores should be done according to published guidance from CDC and the National Institute for Occupational Safety and Health. The CDC and the American Society for Microbiology should develop sampling and analysis guidelines for the other threat agents. Other agencies (such as the U.S. Environmental Protection Agency [EPA] and the FBI) that may be involved in sampling also should be consulted.
Surface sampling with dry wipes led to false negatives at the Wallingford postal facility and to inconlcusive results at the Brentwood postal facility.
Dry-wipe and dry-swab surface sampling should be abandoned in favor of wet-surface swipe techniques. HEPA vacuum surface sampling should be continued as complementary to surface swiping.
Different threat substances require different sampling protocols. The variety of collection approaches currently in use results in widely varying collection and extraction efficiencies, which hamper attempts to quantify the initial extent of contamination.
Sampling and analysis should be standardized. Research should assess the efficiency of collection and analysis for each type of biological agent. Unless the sampling efficiency is known, the amount of contaminant deposited cannot be estimated with confidence.
There is consensus within the federal government regarding the value of a general sampling plan to guide the use of various surface-, air-, and bulk-sampling methods.
The general sampling plan should be the result of the consensus of facility stakeholders; medical, public health, and environmental experts; decontamination tech-
nologists; laboratory analysts; and worker safety representatives. It should encompass three phases: (1) confirmation and contamination baseline, (2) assessment and characterization, and (3) decontamination effectiveness. Some sharing of expertise will be necessary for all groups to be well enough informed to come to consensus.
Paraformaldehyde gas was the preferred decontaminant for buildings at the U.S. Army facility in Fort Detrick, which was home of the U.S. Army Medical Research Institute for Infectious Diseases. EPA has ruled out the use of paraformaldehyde for cleanup after a bioterrorist attack because of concerns about the health effects of the gas.
The committee recommends that the National Cancer Institute lead an interagency task force to reevaluate the possible carcinogenic effects of paraformaldehyde.
ClO2 has been used successfully for decontamination of several buildings: the Hart Senate Office Building, the Brentwood postal facility, and American Media Inc., building.
For now, and given its successful application after the 2001 attacks, ClO2 should be considered the standard for decontaminating buildings—pending further guidance and information from federal agencies. Research leading to the development of new methods and processes should be expected to demonstrate that any new methods have the potential to be at least as effective, safe, and cost-effective as ClO2 for decontamination.
Adequate training of the decontamination team is essential for effective remediation and validation.
EPA and the CDC should establish standards for remediation and validation of contaminated buildings and for the training of remediation teams.
The federal sterilization standard of a 6-log kill—the reduction of the amount of live contaminant by six orders of magnitude—was applied in the Hart Senate Office Building remediation. However, given that 1 g of dried B. anthracis can
contain up to 1012 spores, the current standard could leave a large number of viable organisms.
Current and emerging decontamination techniques should be thoroughly evaluated to ascertain the achievable efficiencies of kill.
Effective response to and recovery from a biological attack requires expertise and input from scientists, public health experts, building engineers, and stakeholders. The response and recovery could be expedited substantially with adequate planning that involves the appropriate scientific expertise and all stakeholders. Although building owners and managers could begin the preplanning that involves the building structure and operations, technical and scientific planning involves expertise that is scattered across government agencies.
Owners and managers of high-value facilities should start planning now. A prompt, well-organized response will be needed to minimize the time a facility is out of commission. The committee recommends that the National Response Plan (specifically its Biological Incident Annex) or some other suitable federal document be expanded to provide more scientific and technical information on biological weapons, decontamination, sampling and surveying, epidemiology, and forensics. The document should describe how a team charged with collecting pertinent information for response to and recovery from a biological attack would operate in the context of a contamination event, which agencies would be responsible for which responsibilities, and who would be responsible for convening the members. The committee recognizes that the formation of such a team might take time and therefore outlines the following immediate, short-term, and long-term goals for building managers and the government to consider:
Immediate goal. Building managers and owners should convene Operations Working Groups that include all relevant stakeholders to devise a response and recovery plan in the event of a biological attack. Because the group would not have all the necessary scientific and technical expertise, the Operations Working Groups should identify the appropriate government agencies and officials to contact in the event of an attack.
Short-term goal. The federal government should identify a mechanism by which groups of experts would be assembled with the appropriate technical and scientific expertise to assist building owners and managers in the event of a biological attack. Those teams of experts would work with Operations Working Groups in the event of an attack to devise the best course of action for response and recovery. It might be modeled after the new central service recently an-
nounced by the United Kingdom’s minister of the environment, which will “provide advice and guidance to responsible authorities during their contingency planning,” among other functions (Department of Environment Food and Rural Affairs News Release of January 25, 2005).
Long-term goal. The federal government should devise a mechanism by which it, and other relevant actors, would be kept abreast of developments and new technologies in surveillance, sampling, and decontamination and iteratively revise standards and policies for decontamination. That mechanism should ensure that updates would get to building managers and owners.
Airports, particularly passenger terminals at airports, are vulnerable to biological attacks, because of the high-profile nature of aviation and because of the densely populated, large, often interconnected interior spaces that such terminal facilities comprise. Aircraft often are connected to terminals so departing aircraft could spread a pathogen to distant points if a biological attack on the terminal were not immediately recognized. The same threat is also presented at airports served directly by urban transit systems—such as rail lines—that are connected to a passenger terminal.
To deal with the aftermath of a biological attack, airport operators should anticipate the need for access to diverse and highly specialized resources, including information on control of air flow. Airport operators should assemble, adopt, and maintain detailed plans to identify, contact, and mobilize those resources. The plans and associated resources should be updated periodically, and they should be stored in locations that would be accessible in the case of an event.
Airport operators are experienced at preparing, adopting, and using specific procedures to cope with the immediate-response aspects of a broad range of emergencies. The same aggressive approach to planning could be usefully applied to the projected aftermath of a biological attack, including the decontamination and reopening sequences that such an attack would occasion. In the event of an actual biological attack, the availability of a soundly drawn plan derived from a comprehensive process would certainly hasten the reopening of a facility.
Plans should contain pertinent physical information on facilities, including floor plans, material characteristics, air circulation patterns, and air sampling data. The plans also should identify, and provide current contact information for, organizations and individuals who could be rapidly mobilized to identify the attacking agent and those who would be available to assist with the actual decontamination.
Acceptance of the decision to reoccupy a facility will be more successful if an Operations Working Group is formed before an event occurs, and if that group includes people with scientific, technical, and medical expertise and those whose daily lives would be affected by contamination of the airport.
Planning should identify the interested parties, form them into a working group, and have them interact regularly in anticipation of coming together to guide an actual recovery effort. That effort should be executed in a manner designed to maximize trust among the various participants and stakeholders.