Responders to the 2001 World Trade Center (WTC) terrorist attacks, who were exposed to caustic dust and toxic pollutants following the 9/11 disaster, suffer from asthma at a rate more than twice that of the general US population, according to new research presented at CHEST 2009, the 75th annual international scientific assembly of the American College of Chest Physicians (ACCP).
As many as 8 percent of the workers and volunteers who engaged in rescue and recovery, essential service restoration, and cleanup efforts in the wake of 9/11 reported experiencing post-9/11 asthma attacks or episodes, compared with 4 percent of the general population. Furthermore, the lifetime prevalence of asthma in WTC responders was marked by a dramatic increase from 3 percent pre-9/11 to a high of 16 percent in each of the years from 2005 through 2007.
"Although previous WTC studies have shown significant respiratory problems, this is the first study to directly quantify the magnitude of asthma among WTC responders compared with the general US population," said Hyun Kim, ScD, Instructor of Preventive Medicine at Mount Sinai School of Medicine (MSSM), New York, NY, and lead author of the analysis which uses data obtained from the federally-funded World Trade Center Medical Monitoring and Treatment Program. "Six years out from 9/11, the World Trade Center Program was still observing responders affected by asthma episodes and attacks at more than double the percentage of people not exposed to World Trade Center dust."
WTC Study Details
In the multicenter clinical study, researchers from the MSSM-coordinated WTC Program reported on health-related findings of 20,843 WTC responders who received an initial medical screening examination during the program's first 5-1/2 years of existence, from July 2002 through December 2007. Asthma outcomes assessed were the following: (1) prevalence of asthma episodes/attacks reported by responders to have occurred during the previous 12 months, and (2) lifetime asthma prevalence, as measured by participants reporting having ever been told by a physician that they had asthma. Results were compared with the US National Health Survey Interviews (NHIS) adult sample data for the year 2000 (pre-9/11) and years 2002 through 2007.
WTC Study Results
In the general population, the prevalence of asthma episodes and/or attacks in the previous 12 months remained relatively constant at slightly less than 4 percent throughout the period from 2000 to 2007. In contrast, among WTC responders, while fewer than 1 percent recalled asthma episodes or attacks during the year 2000, that percentage increased to 8 percent, and then remained constant, through the period from 2005 to 2007. WTC responders were 2.3 times more likely to report asthma episodes/attacks that had occurred during the previous 12 months when compared with the general population of the United States. Additionally, the increase in lifetime prevalence of asthma among responders undergoing their initial program screening any time during the study period grew from a reported 3 percent for (pre-9/11) diagnoses to 13 percent in 2002. The lifetime prevalence of asthma subsequently rose through the years to plateau at 16 percent from 2005 through 2007.
"It is important to note that this report focused on findings from baseline or initial visit examinations," said Philip J. Landrigan, MD, MSc, Ethel H. Wise Professor and Chair of MSSM's Department of Preventive Medicine, and principal investigator of the WTC Program Data and Coordination Center. "Where the data shows an increasing percentage of responders reporting asthmatic episodes, rising to double that seen in the general population, it is clearly vital that we continue to track responders' health and look further into the medical outcomes of this population."
Of the study's rescue and recovery workers, 86 percent were men; 59 percent were Caucasian; and the average duration of work at WTC sites was 80 days. The study followed uniformed and other law enforcement and protective service workers (42 percent), as well as construction workers and other responders who had engaged in paid and volunteer WTC-related rescue and recovery, essential service restoration, and/or debris removal and cleanup efforts.
"Asthma and other chronic lung conditions remain a significant burden for rescue and recovery workers responding to the attacks on the World Trade Center," said Kalpalatha Guntupalli, MD, FCCP, President of the American College of Chest Physicians. "The significant chronic health problems associated with the World Trade Center attacks only reinforces the need for stronger disaster preparedness plans, as well as long-term medical follow-up for 9/11 responders and individuals who respond to disaster-related events."