New Research Outlines Public Health Consequences of World Trade Center Disaster
Longitudinal studies of firefighters, rescue workers and other
personnel who responded to the collapse of the World Trade Center
following the September 11, 2001 attacks have confirmed the presence
of a positive relationship between the intensity and duration of
their exposures to airborne pollutants and the severity of their
Results of the study, conducted by a consortium of researchers
at Mount Sinai School of Medicine, Columbia University, New York
University, Johns Hopkins University, The University of Medicine
and Dentistry of New Jersey, and the University of North Carolina-Chapel
Hill, show exposure-related increases in new-onset cough, wheeze,
shortness of breath, and bronchial hyperreactivity more than 2½
years after the disaster.
In addition, follow-up of pregnant women who were inside or near
the WTC buildings on September 11 found a two-fold increase in the
incidence of small for gestational age (SGA) infants. The study
results will appear in the May issue of Environmental Health
Perspectives, the monthly peer-reviewed journal of the NIEHS.
An electronic copy of the report is available on the online section
The study was funded by the National Institute of Environmental
Health Sciences, one of the National Institutes of Health, the U.S.
Environmental Protection Agency, and grants from The New York Community
Trust and United Way of New York City. Additional support was provided
by the National Institute for Occupational Safety and Health and
the Centers for Disease Control and Prevention.
"Our results indicate that the environmental exposures following
the WTC disaster were associated with profound adverse effects on
respiratory health," said Dr. Philip J. Landrigan, chair of
the Department of Community and Preventive Medicine and director
of Environmental and Occupational Medicine at Mount Sinai, and principal
author of the study.
"The collapse of the towers generated thousands of tons of
particulate matter comprised of cement dust, glass fibers, asbestos,
lead, aromatic hydrocarbons, and organochlorine compounds, many
of which significantly increased the subjects' susceptibility to
bronchial spasms and asthma," said Landrigan. "These respiratory
effects were most pronounced in subjects who were in or around the
WTC buildings during the first 12 hours of the disaster."
Previous studies have documented the acute traumatic consequences
of the September 11 attacks, most notably the occurrence of 2,726
deaths, including 343 firefighters and 60 police officers. Early
clinical assessments noted a high prevalence of respiratory symptoms,
including persistent cough, in firefighters and rescue workers exposed
to the WTC dust.
The present study was designed to yield a comprehensive assessment
of the health impacts of the chemical contaminants on first responders,
construction workers and volunteers who worked initially in rescue
and recovery, and then for several months clearing rubble and debris,
and on residents who lived in the surrounding area.
For their exposure assessment, the researchers focused on five
primary classes of contaminants taken from samples of settled dust
following the collapse of the twin towers. These included airborne
particles, dioxin and other related compounds, asbestos, which was
used for fire insulation in the construction of the North Tower,
aromatic hydrocarbons such as benzopyrene and benzoperylene, and
lead and other trace elements.
Analysis of the data revealed that firefighters were among the
most heavily exposed populations. Of the 10,116 firefighters who
were evaluated, 332 displayed persistent cough accompanied by other
respiratory symptoms so severe as to require at least 4 weeks leave
of absence. "The prevalence of this 'World Trade Center' cough
was directly related to the intensity of the exposure," said
Among firefighters without the cough, many were diagnosed with
bronchial hyperreactivity, a chronic condition which triggers bronchial
spasms in response to ambient air pollutants such as cigarette smoke
and automobile exhaust. This condition was observed in 23 percent
of those with a high level of smoke exposure, and in 8 percent of
those with moderate exposure. "We believe the high alkalinity
of the dust was a major contributing factor to the high incidence
of bronchial hyperreactivity," said Landrigan.
Among ironworkers involved in clean-up and recovery, many of whom
spent several months in and around the disaster site, almost one-third
experienced a chronic cough that began shortly after employment
at the site, 24 percent reported new onset of phlegm production,
and more than 17 percent reported new onset of wheeze. About half
of all workers reported at least one new symptom since they had
begun working at the site.
Preliminary data from clinical evaluation of residents living
within a 1.6-kilometer radius of the WTC site indicate that previously
healthy subjects had a greater increase in cough, wheeze and shortness
of breath than did residents living a greater distance from the
The primary health effect observed in pregnant women who were
inside the towers or within 10 blocks of the WTC at the time of
the disaster was a two-fold increase in the incidence of small for
gestational age infants as compared to pregnant women from a demographically
similar population not known to have been in Manhattan at the time.
"We had hypothesized that long-term exposure to air pollutants
generated by the collapse of the towers might be associated with
an increased risk of small for gestational age births," said
Dr. Trudy Berkowitz, an epidemiologist with Mount Sinai. "Based
on the results of subsequent studies, we have ruled out the potential
role of post traumatic stress disorder in these adverse pregnancy
Researchers are also concerned about long-term health consequences
of asbestos exposure in the wake of the disaster. Asbestos, principally
chrysotile, was used in the construction of the North Tower during
the early 1970's. While some of this asbestos had been removed over
the preceding 30 years, hundreds of tons remained on September 11
and were blasted free.
Ambient air samples showed that asbestos levels in the WTC area
were initially elevated following the September 11 attacks, but
fell to within federal standards after the first few days. "More
research is needed to determine whether long-term exposure to asbestos
fibers might lead to an increased risk of lung mesothelioma, a rare
cancer that has been linked to asbestos exposure," said Landrigan.
"Previous studies have shown the short chrysotile fibers found
in the WTC dust to be the predominant fiber in lung mesothelioma
Reporters may contact Dr. Landrigan at (212) 241-4804.