World Trade Center Disaster and Asthma Type
Environ Health Perspect. doi:10.1289/ehp.12384 available via http://dx.doi.org [Online 27 January 2009]
Referencing: Respiratory and Other Health Effects Reported in Children Exposed to the World Trade Center Disaster of 11 September 2001
As a practicing occupational health physician both in prevention and clinical care, I deeply appreciate the information provided by EHP. The article "Respiratory and Other Health Effects Reported in Children Exposed to the World Trade Center Disaster of 11 September 2001" (Thomas et al. 2008), published in the October 2008 issue of EHP, is consistent with current knowledge about adult consequences of the disaster. My concern is that the term "asthma" can be used to describe two clinical conditions that are not similar in either causation or treatment.
Allergic asthma, usually IgE mediated, is a separate entity clinically from irritant-induced "asthma." The latter is often referred to as reactive airway disease because it is induced by exposure to irritants that may or may not be particulate, and irritant avoidance is an important component of treatment. Allergic asthma responds much better to bronchodilators than reactive airway disease. The latter has been described as having a nitric oxide/peroxynitrite vicious cycle perpetuating biochemical mechanism. Irritant propellants used for treatment of allergic asthma often exacerbate reactive airway disease, and even relatively nonirritating bronchodilators such as albuterol, which help allergic asthma, do not help reactive airway disease.
I believe that it would be useful for Thomas et al. to clarify which condition they are describing: Given the exposure, irritant-asthma (also called reactive airway disease) appears to be the entity under study.
The author's website, chemicalinjury.net, has no external funding, and the author declares she has no competing financial interests.
Grace Ziem
Faculty of Health Sciences
Occupational and Environmental Health
Emmitsburg, Maryland
Website: chemicalinjury.net
Reference
Thomas PA, Brackbill R, Thalji L, DiGrande L, Campolucci S, Thorpe L, Henning K. 2008. Respiratory and other health effects reported in children exposed to the World Trade Center Disaster of 11 September 2001. Environ Health Perspect 116:1383–1390.
World Trade Center Disaster and Asthma Type: Thomas et al. Respond
Environ Health Perspect. doi:10.1289/ehp.12384R available via http://dx.doi.org [Online 27 January 2009]
We appreciate the question raised by Ziem regarding the type of asthma reported in children exposed to the World Trade Center (WTC) disaster of 11 September 2001 (9/11) (Thomas et al. 2008). In our study we found an increase in age-specific asthma prevalence among children < 12 years of age, and a new diagnosis of asthma was strongly correlated with a report of exposure to the dust and debris cloud that occurred as buildings collapsed on 9/11. Among children < 5 years of age, we observed an increased prevalence in asthma diagnosis even among those not exposed to the dust cloud.
We cannot confirm or disprove Ziem's very reasonable suggestion that the asthma seen here was irritant rather than allergen induced. The data on asthma diagnoses were reported by parents or other guardians of the children, using a very simple standardized question. We asked whether a medical provider had ever said the child had asthma, and if yes, whether this occurred before or after 9/11. We did not collect information on severity, treatment, or duration, and did not review medical records. A follow-up survey of the children is under way and includes questions to characterize the asthma illness, but those data are not yet available.
In small children, in addition to airborne irritants and atopy, respiratory viruses may also play a role in initiation or exacerbation of asthma (Schwarze and Gelfand 2000). It is difficult or impossible in a general pediatric setting to differentiate the type of asthma in children, and many pediatricians use the term "reactive airway disease" in children with recurrent wheezing whether or not there appears to be an allergic component.
The airborne contaminants immediately following the 9/11 attacks included a highly alkaline mixture of gypsum, concrete, and synthetic vitreous fibers, further contaminated by metals, organochlorine compounds such as polychlorinated biphenyls and dioxins, and polycylic aromatic hydrocarbons. Later on, settled dust in indoor environments, including residences where many children lived, was found to consist of both fine, coarse, and "supercoarse" (> 10 µm in diameter) particulate matter (Lioy et al. 2006); thus, there was a clear potential for exposure to biologic or allergenic substances. Also, as the cleanup for homes, as well as public areas, was prolonged and difficult, molds could have occurred in some environments and contributed to allergic reactions.
Based on earlier studies, Landrigan et al. (2004) noted that "high alkalinity of WTC dust produced bronchial hyperreactivity, persistent cough, and increased risk of asthma." Increased asthma was subsequently reported in evaluations of 68,444 adults enrolled in the WTC Health Registry (Farfel et al. 2008). Wheeler et al. (2007) found a dose response with increased exposure to the 16-acre "pile" of debris associated with the buildings' collapse and burning. In an overview of health effects in other adults, Farfel et al. (2008) found an association of asthma with exposure to the initial dust cloud generated by the collapse of the twin towers.
We agree with Ziem that, in both children and adults, the exposures observed are more likely related to particulates and other irritants. Further work that includes more detailed histories accompanied by pulmonary function testing is needed to better characterize the pulmonary illness in these individuals.
The authors declare they have no competing financial interests.
Pauline A. Thomas
New Jersey Medical School–UMDNJ
Newark, New Jersey
E-mail: Thomasp1@umdnj.edu
Robert Brackbill
Agency for Toxic Substances and Disease Registry
U.S. Department Health and Human Services
Atlanta, Georgia
Lisa Thalji
Sharon Campolucci
RTI International
Chicago, Illinois
Laura DiGrande
Lorna Thorpe
Steven D. Stellman
New York City Department of Health and Mental Hygiene
New York, New York
Kelly Henning
Bloomberg Foundation
New York, New York
References
Farfel M, DiGrande L, Brackbill R, Prann A, Cone J, Friedman S, et al. 2008. An overview of 9/11 experiences and respiratory and mental health conditions among World Trade Center Health Registry enrollees. J Urban Health 85:880–909.
Landrigan PJ, Lioy PJ, Thurston G, Berkowitz G, Chen LC, Chillrud SN, et al. 2004. Health and environmental consequences of the World Trade Center disaster. Environ Health Perspect 112:731–739.
Lioy PJ. Pellizzari E. Prezant D. 2006. The World Trade Center aftermath and its effects on health: understanding and learning through human-exposure science. Environ Sci Technol 40:6876–6885.
Schwarze J, Gelfand EW. 2000. The role of viruses in development or exacerbation of atopic asthma. Clin Chest Med 21:279–287.
Thomas PA, Brackbill R, Thalji L, DiGrande L, Campolucci S, Thorpe L, et al. 2008. Respiratory and other health effects reported in children exposed to the World Trade Center disaster of 11 September 2001. Environ Health Perspect 116:1383–1390.
Wheeler K, McKelvey W, Thorpe L, Perrin M, Cone J, Kass D, et al. 2007. Asthma diagnosed after September 11, 2001 among rescue and recovery workers: findings from the World Trade Center Health Registry. Environ Health Perspect 115:1584–1590.