Researchers Reflect on Longterm Health Impacts of 9/11
The 25th anniversary of the September 11 attacks is a reminder that the horrific events of that day continue to be felt a quarter century later. While 2,753 people perished in the initial attacks on the World Trade Center, in the time since, hundreds of people exposed in the aftermath have died from related illnesses. Columbia Mailman School researchers have led research uncovering some of those health impacts.
“Twenty-five years later, 9/11 remains a singular catastrophe for New York City. Nearly 3,000 people were killed, hundreds of thousands were directly affected, and the entire city was shaken,” says Alfredo Morabia, a professor of epidemiology who leads the WTC Heart Study. “One meaningful way to honor those who died, and those who continue to suffer, is to ensure that what we learn from their experience serves humanity by improving care and protecting others in the future.”
WTC Health Registry
On the day of the attacks, people in the vicinity of the site were exposed to intense concentrations of fine particulate dust containing hazardous substances, including many known carcinogens, such as asbestos and silica. Fumes and dust also penetrated people’s homes and workplaces in Lower Manhattan, leading to a lengthy and difficult decontamination process.
In November 2001, the New York City Department of Health and Mental Hygiene (NYCDOH) helped create the World Trade Center Health Registry in response to concerns about the potential long-term health effects of exposure to the dust cloud, environmental contaminants, and traumatic events associated with 9/11. Between 2007 and 2015, Professor Stellman served as research director for the Registry, one of the world's largest and longest-running post-disaster health studies, helping evaluate the attacks' health impacts on Lower Manhattan residents, workers, passersby, and rescue/recovery workers.
Stellman authored papers reporting on a variety of outcomes, including cancer, cardiovascular disease, acid reflux, asthma, as well as job loss and early retirement. Many of these findings were published in a special 9/11-themed issue of the American Journal of Industrial Medicine timed for the fifteenth anniversary in 2016. One of these studies reported that rescue/recovery workers at the World Trade Center site had an 11 percent greater overall cancer risk compared to New York State norms. Another presented evidence that by 2011, about 7 percent of non-uniformed rescue and recovery workers had left their jobs prematurely, about half through early retirement and half due to health-related job loss.
Reflecting on the anniversary, Stellman says, “Twenty-five years later, I think one of the most important accomplishments of the World Trade Center Health Registry is that it allowed us to turn a catastrophe of enormous scale into an extraordinary opportunity for learning. We could not know in 2001 which health consequences would emerge quickly and which would take years or decades to become apparent. The Registry made it possible to follow people over time and to document not only physical and mental health effects, but their consequences for work and everyday life.”
WTC Pregnancy Study
Julie Herbstman, professor of environmental health sciences and director of the Columbia Center for Children’s Environmental Health, and colleagues led several studies assessing the effects of air pollutants released by the destruction of the World Trade Center towers on fetal growth, respiratory health, and cognitive development. Participants in the Columbia University World Trade Center birth cohort included 329 women with singleton pregnancies enrolled between December 13, 2001, and June 26, 2002, at one of three hospitals located near the disaster site.
In a study published in Environmental Health Perspectives, they found that babies born to women living within two miles of the site in the weeks after 9/11 were, on average, born five ounces lighter and one-third of an inch shorter than babies born to women living farther away. In addition, women who were in the first 13 weeks of pregnancy on 9/11, regardless of where they lived or worked, had slightly shorter pregnancies by an average of 3.6 days. Another study in the journal Environmental Pollution found evidence that exposure to the disaster during pregnancy increased levels of PFAS ("forever chemicals") in mothers. The researchers say the findings point to the need for long-term medical monitoring of children exposed to the World Trade Center disaster in utero.
WTC Heart Study
In 2011, President Barack Obama signed the James Zadroga 9/11 Health and Compensation Act into law. Named after James Zadroga, a New York Police Department officer whose death was linked to exposures from the World Trade Center disaster, the law funded and established the World Trade Center Health Program to provide medical treatment for responders and survivors with health complications related to 9/11.
Since 2012, Alfredo Morabia, professor of epidemiology, has led the WTC Heart Study, which examines the risk of cardiovascular disease among 6,481 first responders involved in the 2001 policing and cleanup activities. The CDC and NIOSH-funded research drew on participants enrolled in the World Trade Center Health Program.
In a study published in 2018 in the journal Circulation: Cardiovascular Quality and Outcomes, Morabia and colleagues found that first responders who developed PTSD related to the traumatic physical and psychological conditions at Ground Zero had about twice the risk of cardiovascular disease than those who did not develop PTSD. In ongoing work, they are looking at whether PTSD has a direct effect on cardiovascular disease or whether other risk factors mediate it.
The World Trade Center Health Program pays for the treatment of a range of illnesses for those exposed to the disaster, including respiratory diseases, some cancers, as well as mental health conditions such as PTSD. After the study’s publication in 2024, the program considered cardiovascular disease for inclusion as a World Trade Center-related illness, but as of today, it still does not cover it.
Reflecting broadly, Morabia says, “Around the world, people endure the health consequences of war, terrorism, and natural disasters, often on a similar or even greater scale. What distinguishes the World Trade Center experience is that the Zadroga Act created a sustained framework for monitoring, research, and care, allowing us to understand the long-term health effects of 9/11 and how they might be prevented or mitigated.”