Vol. 16 •Issue 18 • Page 14
Legacy of a Disaster
Ground Zero and Environmental Respiratory Disease
The respiratory system is a prominent organ system openly exposed to the external milieu and, thus, vulnerable to environmental exposures. Additionally, it is susceptible to toxic injury.
The human lung is a wonder, an ecosphere designed to intake 20,000 liters of air each day. The actual surface area is about 150 square meters or about that of an Olympic tennis court. This labyrinth houses various defense mechanisms such as pulmonary macrophages and the mucociliary escalator; however, airborne toxins and toxicants can overwhelm them.
It is almost two years since the terrorist attacks of Sept. 11, 2001, and lingering health effects have been evolving in emergency response personnel and other populations exposed to airborne toxicants generated by the destruction of the World Trade Center (WTC) buildings. During the destruction and aftermath, tens of thousands of people were exposed to combinations of destruction-related chemicals and particulate matter (PM). Both pyrolytic/combustion by-products and dusts containing organic and inorganic species such as benzene, toluene, dioxins, furans, heavy metals, silica, asbestos and fiberglass were generated. These substances remained airborne until they settled in and around the disaster site. Then, secondary re-suspension of PM occurred during rescue, recovery and clean-up efforts.
Megatons of building and aircraft components and jet fuel became airborne. The explosions, fires and collapse of the WTC buildings culminated in a catastrophic event that generated an aerosol plume impacting many workers, commuters and nearby residents.
The actual composition of airborne dusts and PM, as represented by bulk samples collected around the impact site and monitored as ambient PM, consisted of construction materials, soot, paint and glass fibers. Levels of polycyclic hydrocarbons (PAH) were indicative of unburned jet fuel, plastic and other ignited materials.
In an environmental assessment conducted by researchers from the New York University School of Medicine’s Department of Environmental Medicine, elemental and organic carbon concentrations, particles and particle mass, asbestos, trace elements, soluble ions, and pH of aqueous dust suspensions were measured. Interestingly, the researchers discovered only trace amounts of asbestos both in the bulk samples and as particles larger than 10 microns. No asbestos was recovered in dust particles less than 2.5 microns, according to the report. Some inorganic trace elements were found to be at concentrations above background values.
Fine PM outside the rescue area did not exceed regulatory standards during sampling, though short-term, elevated “excursions” of PM levels were observed at one point.
The environmental health impact and the human exposure assessments remain hotly debated topics, especially in relation to medico-legal implications and litigation for compensatory damages.
It is important to remember that a multitude of emergency personnel, commuters and residents were in or near this disaster environment without respiratory protection, many for a prolonged time. In addition, the alkalinity/high pH and fiberglass in the WTC dust proved to be highly irritating and toxic to the eyes and the conducting airways, which may have contributed significantly to the evolution of what has become known as WTC cough.
Many firefighters reported cough related to ambient exposures, which was often immediate in onset and not prolonged in duration. However, during the subsequent months, a large number of firefighters were found to have severe, persistent cough and dyspnea; these persons required extended medical leave from firefighting duties.
Did rescue and recovery efforts at the WTC impact respiratory health? The Medical Department/Bureau of Health Services (BHS) of the New York City Fire Department (FDNY) is responsible for the medical aspects of the respiratory protection program for the firefighters. The BHS also manages work-related medical leave, return-to-duty authorizations and related occupational health and safety issues.
It is well established that many members of the fire service are exposed daily to tobacco smoke, first or second hand. There is little doubt that tobacco smoke can impair respiratory defenses and act synergistically with other environmental exposures. Also, firefighters are exposed to hazardous materials, inhaled toxicants and fuel exhaust almost as a matter of routine.
Before and after 9-11, FDNY-BHS had conducted routine, baseline pulmonary function studies, including questionnaires, spirometry results and chest radiographs. Metacholine challenges in a group of exposed but asymptomatic firefighters also were performed.
The relentless rescue, recovery and fire suppression efforts involved approximately 11,000 FDNY members who were exposed to respiratory irritants and airborne toxicants. Sadly, 343 or 3 percent of the department’s firefighters died in the collapse of the WTC. An additional 3 percent developed protracted respiratory disability. Of those, less than half had returned to firefighting duties at the end of a seven-month period of observation.
The major findings indicated that of those who were present at the WTC collapse, 8 percent had disabling persistent cough associated with reduced forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1). More than 20 percent had bronchial hyper-responsiveness as indicated by the results of metacholine bronchoprovocation. Disabling cough and bronchial hyperresponsiveness developed in fewer of those exposed to the WTC site on subsequent days.
Obviously, the firefighters with WTC cough had reduced lung function as indicated by pulmonary function testing. Spirometry testing performed for the exposed firefighters was conducted under different conditions from those used for OSHA respiratory protection programs. Therefore, some reductions in FVC and FEV1 among symptomatic firefighters may be due to method and patient performance.
Paradoxically, the decreased spirometric values related to the FVC and FEV1 were proportional despite clinical data and imaging studies indicating predominant airway injury due to associated environmental exposure. Although this finding may be considered unusual, some patients with reactive airways demonstrate normal FEV1/FVC ratios, occasionally referred to as a non-specific pattern.
Patients who displayed a predominance of lower airway symptoms had correlating spirometric and radiographic abnormalities. Further data is expected to evolve during on-going assessments.
PERSONAL PROTECTIVE EQUIPMENT
In all hazardous materials incidents, the use of appropriate fit-tested personal protective equipment (PPE) and adherence to protective protocols and strategies are important. In the hazardous atmosphere of Ground Zero, less than 22 percent of the firefighters without WTC cough reported frequent respirator use in the first week.
Also, 93 percent of symptomatic individuals reported that they used their respirators “rarely or not at all” on day one, 85 percent on day two and 76 percent on days three to seven.
Frequent use was reported by 65 percent during week 2.
Many factors may have contributed to this non-compliance, such as discomfort, poor fit, clogging of respiratory cartridges and inadequate access to or re-supply of filters. Also, PPE, even a simple dust mask, is physically unpleasant to wear.
The presumptive etiologic agents associated with WTC cough and related respiratory dysfunction is speculative and probably multifactorial. Although the CDC did not identify harmful levels of airborne toxicants in their sample analyses, ambient sampling was undertaken after most airway injury had already occurred in the acute phase of disaster response.
Clinical data and experimental combustion toxicology studies, for example, provide the medical and scientific bases that implicate reactive oxygen species, such as ozone and oxides of nitrogen (NOx) and pyrolytic by-products such as volatile organic compounds (VOCs) as causative agents in acute and chronic airway hyperresponsiveness.
Although a large number of respirable aerosols were generated during the WTC collapse, there appears to be little qualitative evidence to suggest that inorganic dust precipitated acute airway hyperresponsiveness. However, there is a substantial body of clinical and scientific evidence that can quantify and support that fiberglass, asbestos, coal dust and other substances are implicated in the development of occupational pneumoconioses and other environmental respiratory diseases like occupational asthma.
Respirable particulate matter pollution has been associated with higher incidences of reactive airways disease and other respiratory pathology.
The lingering adverse impact on post-9/11 respiratory health provides a valuable and unfortunate set of lessons in disaster preparedness and conventional occupational medicine. Disasters of a similar or worse scale not only are possible, but also are highly probable, given current geopolitical situations and security threat assessments. Furthermore, conventional occupational and environmental hazards abound in our highly industrialized society.
Emergency preparedness efforts must be able to provide the best possible protection for our citizens, including emergency response personnel and health care providers. Basic and applied research efforts that address human health effects of occupational and environmental exposures must be expanded and the development of protective countermeasures must be intensified.
In our vulnerable and technological society, we must enhance our preparedness and response capabilities to address poorly defined and unconventional threats. Adverse effects can be minimized and controlled through thoughtful preparation, hazard containment and strict adherence to personal protective countermeasures during rescue and recovery efforts.
Meanwhile, assessing and documenting the health status of exposed survivors of the WTC tragedy, as well as other disasters, while assuring complete access to comprehensive health care over the long term, is an important obligation of this nation’s scientific and medical resources.
Frank G. Rando is an authority on toxic inhalation/toxic respiratory disabilities, environmental exposure assessment, hazardous materials toxicology and emergency response and weapons of mass destruction. He is a member of the AARC Committee on Disaster Response and Preparedness and the Arizona-1 Disaster Medical Assistance Team. He may be contacted at firstname.lastname@example.org.