The call for articles on the long term health effects of the 11 September 2001 terrorist
attacks (9/11) has resulted in twenty-three papers that add a significant amount of
information to the growing body of research on the effects of the World Trade Center
(WTC) disaster almost two decades later. The attacks on 9/11 were a paradigm altering
event in US history and have had major repercussions in the political landscape and
response to terrorism. The toll of 9/11 includes the continued impact of accumulated
health effects among those who were directly exposed to either the air pollution or
re-suspended material that resulted from the collapse of the two WTC towers, and physical
injuries or psychological trauma. This includes a wide range of physical and mental
health disorders that continue to plague thousands of people 18 years later as well
as newly identified conditions emerging as a result of prolonged disease latency.
This was recently highlighted by the addition of “The Memorial Glade” at the WTC site
that acknowledges illnesses and deaths years after the towers collapsed [1].
The articles in this special issue also demonstrate the importance of the medical
monitoring of the wide range of populations exposed to unprecedented levels of physical
and psychological insult from the 9/11 attacks. As such, the reports in this issue
represent research findings from the clinics supported by World Trade Center Health
Programs and the epidemiological follow-up by the World Trade Center Health Registry.
Although the majority of the articles represent rescue, recovery, and clean-up workers
(12), some other non-rescue recovery groups included in the special issue are residents
of Chinatown, just 10 blocks from ground zero (Kung et al. 2019 [2]), and other residents
of lower Manhattan (Antao et al. 2019 [3]).
Respiratory and lung problems are among the most prevalent and highly persistent physical
health problems arising from 9/11 exposure to dust clouds from the collapsing building
and the subsequent re-suspension of dust (Aldrich, 2010 [4]). In this issue, there
are nine respiratory-related papers that provide new insights into the long term consequences
of lung damage from 9/11 exposure not reported in previous research. These papers
highlight the chronic and still emerging health sequela of 9/11 exposure. An analysis
of cleaning practices by residents in lower Manhattan showed that cleaning with dry
methods was associated with more types of respiratory symptoms than other cleaning
methods (Antao, 2019 [3]). Other papers delved into the underlying physical and biological
aspects of pulmonary illness among persons exposed to 9/11 (Liu, 2019 [5]; Kwon, 2019
[6]; Pradhan, 2019 [7]). Liu et al. (2019) used chest tomography (CT) and reported
that firefighters with high intensity exposure on 9/11 had increased risk of bronchial
wall thickening, emphysema, and air trapping. They correlated the CT-identified abnormalities
with respiratory symptoms. A second paper also evaluated the role of metabolic syndrome
biomarkers (MSBs) among firefighters (e.g., elevated systolic blood pressure and insulin
resistance) in airway hyperactivity (Kwon, 2019 [6]). They reported that given 9/11
exposure, having three or more MSBs increased airway hyperactivity beyond that associated
with 9/11 exposure. Another paper that evaluated the bronchodilator response among
community members exposed to 9/11 found that a proportion of small airway problems
were irreversible, which was predicted by the bronchodilator response at initial visits
(Pradhan, 2019 [7]). Two other papers evaluated the increased risk of asthma control
issues and quality of life as a function of indoor allergens (Rojano, 2019 [8]) and
air pollution/irritants (Yung, 2019 [9]). In addition, an emerging respiratory condition,
pulmonary fibrosis (PF)—a common long term sequelae of occupational dust exposure—was
documented in a paper based on data from the World Trade Center Health Registry for
which there was evidence of a dose-response relationship with the level of exposure
among rescue/recovery and other 9/11 workers and the likelihood of PF (Li, 2019 [10]).
Three other papers reported additional findings on a condition known as sarcoidosis
(Cleven, 2019 [11]; Hena, 2019 [12]) and sarcoid-like granulomatous (Sunil, 2019).
Sarcoidosis is a rare autoimmune disease that can affect any organ, but among rescue,
recovery, clean-up workers, it has been previously reported as granulomatous disease
involving the thoracic organs (Izbicki, 2007 [13]; Jordan, 2011 [14]), primarily among
firefighters or other rescue, recovery, or clean-up workers arriving early at the
WTC site. One paper in this issue describes sarcoidosis among community members who
were patients at the WTC Environmental Health Center (Hena, 2019 [12]). Another paper
focused on the genetic predisposition for sarcoidosis in a case control study (Cleven,
2019 [11]). Sunil (Sunil, 2019 [15]) reported a detailed pathology review of sarcoid
like granulomatous disease (SGD). Out of seven cases, five were definite SGD and had
high exposure to 9/11 WTC dust.
In addition to respiratory disease, other long term adverse health outcomes of WTC-related
exposure include neurologic conditions and cancer. Papers in this issue focused on
these emerging conditions including peripheral neuropathy (Colbeth, 2019 [16]), paresthesia
(Thawani, 2019 [17]), and thyroid cancer (van Gerwen, 2019 [18]; Tuminello, 2019 [19],
see Gargano, 2018 [20] for a review of non-respiratory physical health conditions).
Two studies focused on neuropathic conditions that included peripheral neuropathy
among New York City firefighters and emergency medical workers (Colbeth, 2019 [16])
and parenthesia among community survivors who received treatment at one of the WTC
Health programs (Thawani, 2019 [17]). Potential exposures for neuropathic conditions
on 9/11/2001 and afterward included heavy metals and complex hydrocarbons. Both studies
used the self-reporting of unusual and painful sensations such prickling, burning,
or aching pain in the limbs. Colbeth et al. reported a 35% increase in the likelihood
of peripheral neuropathy symptoms among those with the highest 9/11 exposure versus
low/no exposure. Similarly, Thawani et al. reported a significant hazard ratio of
1.4 for parenthesia among persons who had a job that required cleaning-up materials
resulting from building fires and buildings collapsing. The physical health outcome
of cancer was represented by two papers on thyroid cancer (Tuminello, 2019 [19]; van
Gerwen, 2019 [18]). Thyroid cancer has been identified as a cancer with a higher expected
incidence among potential WTC-exposed persons (Zeig-Owens, 2011 [21]; Li, 2016 [22];
Solan et al., 2013 [23]). Tuminello (2019) evaluated the possibility that increased
surveillance for thyroid cancer among WTC survivors could account for the elevated
thyroid cancer incidence. In another study (van Gerwin, 2019 [18]) that evaluated
thyroid cancers derived from the same population, the authors compared the pathological
characteristics of cancer tumors of WTC exposed to non-WTC cases in order to assess
whether there were more false positives among the WTC exposed that would suggest a
surveillance bias.
The high prevalence of adverse mental health, especially post-traumatic stress disorder
(PTSD), has been documented among survivors of 9/11 (Brackbill, 2009 [24]; Stellman,
2008 [25]), in addition to the persistence of PTSD (Pietrzak, 2014 [26]; Maslow, 2015
[27]; Welch, 2016 [28]). A number of papers in this issue addressed the characteristics
of those receiving or not adequately receiving mental health treatment and some measurement
of the effectiveness of treatment (Jacobson, 2019 [29]; Kung, 2019 [2]; Rosen, 2019
[30]; Bellehsen, 2019 [31]). Based on data from the World Trade Center Health Registry
(WTCHR), 38% of enrollees reported they had utilized mental health counseling or therapy
sometime in the 15 years after 9/11, with younger persons more likely to seek counseling,
but older persons perceiving treatment to be helpful (Jacobson, 2019). Those with
persistent PTSD perceived treatment to be less helpful. Another paper also used WTCHR
information to characterize unmet mental health care needs for a specific sub-group
of Asian WTCHR enrollees, who typically underutilize mental health services (Kung,
2019 [2]). Among the 2300 Asian WTCHR enrollees included in the study, 12% said that
they had an unmet mental health care need, for whom 69% reported attitudinal barriers
(e.g., I do not need to see a doctor) to utilizing mental health care, 36% said there
were cost barriers (e.g., lack of health insurance), and 28% had access barriers (e.g.,
where to go for doctor, childcare, transportation issues). Two other 9/11 mental health
papers used information on patients enrolled in a community WTC Health Program (Rosen,
2019 [30]) and rescue/recovery worker health program (Bellehsen, 2019 [31]). Among
patients who reached the criteria for PTSD at the first visit, 77% continued to meet
the criteria for PTSD 3 to 4 years later (Rosen, 2019 [30]). Further analysis indicated
that some reduction in PTSD symptoms was associated with treatment. The second paper
evaluated the extent to which patients were receiving evidence-based treatment (EBT)
by community health providers. Like the Rosen et al. paper, they employed baseline
and follow-up information in addition to providers reporting their use of EBT. However,
after an independent review, 12% of the patients were likely to have received full
EBT, and another 40% received some elements of EBT.
Some papers in this issue fittingly addressed the long-term effects of 9/11 exposure
on both physical and mental functioning. For instance, Brackbill et al. (2019) [32]
assessed the self-reported physical and mental health functioning of persons who were
injured on 9/11 15 years after the attack. The severity of injury was associated with
physical functioning, but not with mental health functioning; PTSD history also had
a significant additive influence on the effect of injury on physical functioning.
Using a more objective measure of functionality referred to as handgrip strength,
which is a measure of general health status and biomarker of aging, Mukherjee (2019
[33]) reported that rescue/recovery workers with probable PTSD had significantly lower
HGS than those without PTSD or depression. Apart from functionality and physical loss,
there is concern that persons exposed to 9/11 could be at greater risk of cognitive
impairment, memory loss, or confusion at a faster rate than would be expected normally
with age. Seil (2019) [34], using the WTC Health Registry data, derived levels of
protective factor or cognitive reserve (based on educational level, employed or not,
social support, and level of physical activity) for cognitive impairment and found
that higher levels of cognitive reserve were associated with less self-reported memory
loss for both persons with and without a history of PTSD. Two other aspects of quality
of life are represented by papers on early retirement and post-2019 (Yu, 2019 [35]).
Among the Lower Manhattan residents and area workers, a history of PTSD and the number
of 9/11 related chronic conditions were associated with early retirement (retired
before 60). In addition, income loss among those who retired was more likely among
those with the highest level of exposure. In the quality of sleep study, it was reported
that 9/11 related co-morbidities including gastroesophageal reflux disease, chronic
rhinosinusitis, PTSD, anxiety, and depression were associated with a great proportion
of sleep related complaints (Ayappa, 2019 [36]). With the presence of these co-morbidities,
apnea had no significant impact on sleep quality.
The papers in this special issue clearly document the continued long term effects
of the September 11, 2001 WTC disaster on a wide range of health and quality of life
issues. They underscore the need for ongoing health monitoring of these highly exposed
populations while also representing the cutting edge research on subject areas from
the biological underpinnings of 9/11 related respiratory disease to the effectiveness
of treatment for mental health problems related to 9/11. This work continues to inform
the World Trade Center Health Program for those most affected by the disaster. While
this is a uniquely exposed population, this large body research will inform responses
to, and the monitoring of, populations exposed to future human caused and natural
disasters.