Millions of people were affected by the September 11 terrorist attacks — from physical and mental health problems to financial loss. This large and diverse population had different exposures after the collapse of the World Trade Center (WTC), and health effects have varied as a result.
More than a decade of studies suggest that while the majority of people exposed to the WTC disaster are healthy and symptom free, thousands of individuals—including rescue, recovery and clean-up workers and people who lived, worked or went to school in Lower Manhattan on 9/11—have developed chronic, and often co-occurring, mental and physical health conditions.
What We Know
Large epidemiological studies conducted by the Health Department’s WTC Health Registry suggest that post-traumatic stress disorder (PTSD) symptoms are the most common health effect of 9/11. Experienced by as many as 20% of adults who were directly exposed to the WTC disaster, this is roughly 4 times the rate of PTSD symptoms typically found in the general population.
Risk factors for probable PTSD included:
intense dust cloud exposure or suffering an injury on 9/11
being on a high floor of the World Trade Center, evacuating late or working for an employer that sustained fatalities.
witnessing horror or knowing someone killed or injured on 9/11
little or no social support after 9/11
Rescue and recovery workers who started rescue work on or soon after 9/11 or who worked at the WTC site for a long time were also more likely to develop PTSD. Workers from non-emergency occupations also suffered high rates of PTSD.
People who experienced trauma before or after 9/11, such as losing a job after the attacks, or urban or domestic violence, were at increased risk for developing PTSD.
Despite widespread evidence of PTSD among all exposed groups, studies have not shown an increase in suicide up to four years after 9/11.
Depression, anxiety and substance use disorders have not been as well studied as PTSD among WTC-exposed people. The studies to date, however, suggest that the prevalence of these conditions increased shortly after 9/11 and there is significant co-occurrence, or co-morbidity with PTSD in WTC-exposed groups.
Those exposed to WTC-related dust were more likely to develop respiratory symptoms, sinus problems, asthma or lung problems. One in 10 Registry enrollees developed new-onset asthma within 6 years of 9/11, 3 times the national rate. New cases were highest during the first 16 months after 9/11.
Intense dust cloud exposure on 9/11 increased everyone's risk for developing asthma. The risk was also increased among:
rescue, recovery and clean-up workers who arrived early at the WTC site or worked at the WTC site for long periods of time;
Lower Manhattan residents who didn't evacuate their homes;
Lower Manhattan residents and office workers who returned to homes or workplaces covered with a thick coating of dust; and
people who both lived and worked in lower Manhattan after 9/11.
Steep declines in pulmonary function first detected among firefighters and emergency medical service (EMS) workers within a year of 9/11 have largely persisted even among those who never smoked. It is estimated that four times as many firefighters and twice as many EMS workers had below-normal lung function for their ages six to seven years after 9/11 as they did before the attacks. Among the few active smokers, pulmonary function declines were even greater than for non-smokers.
Studies also have identified persistent abnormal pulmonary function in other WTC rescue and recovery workers, including police, and in Lower Manhattan residents and area workers.
Both epidemiologic and clinical studies demonstrate substantial comorbidity of mental health conditions with respiratory illness in WTC-exposed groups.
Many WTC-exposed people report heartburn, acid reflux or other gastroesophageal reflux symptoms, often with respiratory or mental health symptoms. Since these symptoms are common among the general population, more research is needed to determine the connection between them and WTC exposure.
Several studies have suggested that WTC exposure is associated with sarcoidosis (an inflammation that can affect any organ, but typically affects the lungs) among rescue, recovery and clean-up workers who worked on the debris pile. However, these studies cannot rule out the possibility that increased medical attention and testing may be responsible for the detected increases in sarcoidosis rates among WTC workers.
Findings have been inconsistent regarding the impact of WTC exposure on birth outcomes. Some studies suggest that reduced fetal growth found in some babies delivered by women who were pregnant on 9/11 may be related to the stress caused by the attacks. Other studies, however, found no impact of WTC exposure on birth outcomes.
Few studies have addressed the impact of WTC exposure on child and adolescent health, especially physical health. Data from the WTC Health Registry's 2003-2004 survey of 3,000 children and adolescents indicate that very young children caught in the dust cloud on 9/11 were at increased risk for developing asthma. Six to seven years after 9/11, the Registry found that respiratory symptoms were associated with WTC exposures in younger children and with behavior problems in adolescents.
Although cancer takes many years, even decades, to develop 3 early WTC cancer studies based on diagnoses confirmed through 2008 have been published. This research suggests that long-term monitoring of cancer occurrence among WTC-exposed individuals is warranted:
FDNY found that nearly 9,000 firefighters with WTC exposure may be at greater risk for cancer than firefighters who weren’t exposed.
The Registry focused on cancers occurring in 2007-2008 because they are more likely to be related to WTC exposure than earlier cancers and found small increases in rates of prostate cancer, thyroid cancer and multiple myeloma, a blood cancer, among nearly 34,000 WTC rescue and recovery workers in comparison to New York State residents after adjusting for age, race/ethnicity and sex. No increases were found during the same time period among Lower Manhattan residents, area workers and students enrolled in the Registry.
Prostate and thyroid cancer rates were higher than expected among nearly 21,000 rescue and recovery workers enrolled in the WTC Health Program in comparison to rates in New York, New Jersey, Connecticut and Pennsylvania in where the majority of workers lived
The only WTC-related mortality Study to be published showed that Registry enrollees were less likely to die in the eight years of follow-up than people in the general New York City population. The study, however, also showed that among Lower Manhattan residents, area workers and passersby in the Registry, those with higher levels of WTC exposure may be at greater risk for all-cause mortality and cardiac-related mortality in particular compared to those with intermediate or lower levels of WTC exposure.
More about the prevalence and persistence of WTC-related conditions. The WTC Health Registry completed its third health survey of more than 68,000 adult enrollees and more than 1,300 adolescents and their parents in September 2012, and has begun planning its fourth health survey.
The extent to which people with potential WTC-related health conditions are receiving treatment, and what coverage gaps remain
The effectiveness of treatment for patients with WTC-related mental and physical health conditions
Whether or not findings from early cancer and mortality studies are replicated, if they are replicated in different populations with different exposure levels, and if they change over time.
The role WTC-related illness may play in cardiac disease and diabetes
How prevalent WTC-related depression and substance use are among WTC-exposed populations
The long-term impact of ongoing WTC-related physical health conditions on long-term mental health
The long-term impact of 9/11 on children who went to school or who lived in the area, whose parents were part of the rescue and recovery effort or who lost family members
Monitoring and Treatment for 9/11-Related Health Conditions
No matter where they live now, people affected by 9/11 are eligible for treatment and medication with no out-of-pocket costs at the WTC Health Program, which includes New York City’s 3 Centers of Excellence.
The Centers and the WTC Health Registry—all funded by the federal government—continue to provide clinicians, epidemiologists and other researchers with the kind of evidence that will help answer some of the unknowns over the long term. Their ongoing work will help better identify the people who are at greatest risk for becoming ill and further refine treatment options for people who already are sick.