Twenty-five years after the September 11th terrorist attacks, researchers are preparing to study a group of people whose experiences have received considerably less attention than those of the firefighters, police officers, and other adults who responded to the disaster.
They were children.
Some were old enough to remember the planes striking the World Trade Center. Others were infants. Some were still in the womb. Many lived in Lower Manhattan or attended school nearby and were exposed to the enormous cloud of dust and debris created when the towers collapsed.
Now, a major federal research effort is being established to examine what that exposure may have meant for their health over the course of their lives.
The new study is one of the more significant developments surrounding the 25th anniversary of September 11th, but it also raises an uncomfortable question. Why has it taken a quarter-century to establish a major study specifically designed to understand the health effects of 9/11 exposure on children?
A Population That Was Easy to Overlook
In the immediate aftermath of September 11th, the most visible victims were the people who died in the attacks and the emergency workers who rushed toward the burning buildings.
The health consequences that emerged afterward also initially centered heavily on adults who had worked at Ground Zero or participated in the rescue, recovery, and cleanup effort.
That focus was understandable. First responders and cleanup workers experienced some of the most intense exposures to the dust, smoke, and other contaminants released by the destruction of the World Trade Center.
But thousands of children were also living, attending school, or spending time in the area.
Reuters reported this week that approximately 25,000 children were living or attending school near the World Trade Center on September 11, 2001. That population included children who were exposed directly to the dust cloud as well as those who were exposed through contaminated air, buildings, and environments in the weeks and months that followed.
The problem was that many of these children were not included in the earliest large-scale health studies.
Researchers also faced a practical problem that became more difficult with every passing year. The children grew up.
They moved away. They went to college. They began careers and families of their own. Tracking down people who were children in 2001 became increasingly difficult.
That makes the creation of a new research cohort especially important.
Congress Called for a Youth Research Cohort
The idea of studying the long-term health effects of 9/11 exposure on young people is not entirely new.
Congress established the legal framework for such research in legislation enacted in 2022. The law directed the World Trade Center Health Program to establish a research cohort large enough to conduct future studies into the health and educational effects of exposure among people who were 21 or younger when they were exposed.
The new initiative is now moving toward implementation.
The Centers for Disease Control and Prevention’s National Institute for Occupational Safety and Health, which administers the World Trade Center Health Program, has announced plans for a World Trade Center Youth Research Coordinating Center.
In August, the program released a grant opportunity forecast for the center, signaling that the formal funding process was beginning.
Reuters reports that the study could receive as much as $50 million and is expected to begin by July 2027. The research is intended to follow people who were 21 or younger, or were in utero, and who lived in Lower Manhattan or Brooklyn during the relevant period. Researchers also plan to include a comparison group of people who were not exposed.
The goal is not simply to document what happened to a group of children two and a half decades ago. Researchers want to understand whether exposure during childhood has produced health effects that persist into adulthood.
There Were Already Warning Signs
Although a comprehensive youth study is only now being organized, researchers have not been completely in the dark about what happened to children exposed to the disaster.
Earlier studies have found evidence of health problems among young people who were exposed to the World Trade Center disaster.
A CDC-published study examining hospitalizations among people who were younger than 18 on September 11th found that exposure to the dust cloud was associated with hospitalization for respiratory conditions. The study also found an association between post-traumatic stress symptoms and hospitalization for mental health or substance-use conditions.
The research followed 3,248 people who had been children at the time of the attacks and were enrolled in the World Trade Center Health Registry. Researchers examined hospitalizations between the participants’ enrollment in 2003 and the end of 2016.
The findings do not establish that every health problem experienced by someone exposed to 9/11 was caused by that exposure. They do, however, demonstrate why continued research is necessary.
The researchers themselves concluded that continued monitoring would be important for understanding the long-term effects of 9/11 exposure.
That long-term question has become even more important as the children of 2001 have entered middle age.
Twenty-Five Years Later, the Health Story Is Still Developing
The new youth study is arriving at a time when researchers are still learning about the health consequences of September 11 among adults.
The New York City Department of Health said this week that its World Trade Center Health Registry is tracking approximately 71,000 people who were exposed to the aftermath of the attacks. The registry was created in 2002 and has followed participants for more than two decades.
According to the city’s Health Department, registry research has contributed to a better understanding of respiratory illnesses, cancer, gastrointestinal disease, mental health conditions, autoimmune diseases, hearing problems, and cognitive impairment among people exposed to the World Trade Center disaster.
The department also reports that people who experienced 9/11 as children were about twice as likely to develop asthma as the general New York State population and have an increased likelihood of depression.
Those findings are important because they demonstrate how a disaster that occurred a quarter-century ago can continue to produce new health questions.
The children who were exposed in 2001 are no longer children.
They are adults who have spent most of their lives after September 11th.
Why Childhood Exposure Is Different
There is a particular reason scientists are interested in people who were exposed when they were young.
Children are still developing. Their lungs, immune systems, and other biological systems are changing throughout childhood and adolescence. An environmental exposure that affects a developing child could potentially have consequences that are different from those experienced by an adult.
There is also the psychological dimension.
A child may not have understood what was happening on September 11. A young child may remember only fragments of the day. Another may have been too young to remember it at all but could still have experienced the environmental exposure and the disruption that followed.
The combination of physical exposure and psychological trauma creates a complicated research problem.
A study that follows these people over time can help researchers separate those factors and determine which health outcomes appear more frequently among people who were exposed.
That information could have implications beyond 9/11.
Lessons for the Next Disaster
One of the most important reasons to study the children of September 11th is that another disaster will eventually happen.
It may not resemble the World Trade Center attacks. It could involve a major industrial accident, a wildfire, a chemical release, a natural disaster, or another event that exposes children to dangerous substances.
When that happens, public health officials will need to know how to monitor those children.
The lessons learned from the World Trade Center population could help determine what information should be collected immediately after a disaster, how children should be monitored, and what kinds of health problems might take years to emerge.
That is one reason long-term research matters.
A disaster ends on the day the immediate emergency is over. Its health consequences may not.
Research Takes Time
There is also something important about the timing of this study that is easy to miss.
The fact that the research is beginning 25 years after September 11th does not necessarily mean that scientists have ignored the health of children. The World Trade Center Health Registry has followed young people, and other studies have examined specific health outcomes.
The challenge is that studying long-term effects is inherently difficult.
Researchers have to locate participants, establish accurate exposure histories, and obtain reliable health information. They have to account for factors that have nothing to do with September 11th. They need comparison groups and sufficiently large populations to identify meaningful differences.
And then they have to wait.
That is particularly true when studying diseases or conditions that can take decades to develop.
The people who were children in 2001 have now provided researchers with something that did not exist 25 years ago: time.
A Study That Should Have a Long Life
The creation of the youth research program is therefore about more than filling a historical gap.
It is an acknowledgment that the health consequences of September 11th did not end when the smoke cleared or when Ground Zero was cleaned up.
They have continued to unfold.
The World Trade Center Health Registry will continue following its participants, while the new youth research effort will create a more focused opportunity to study people who experienced the disaster during childhood.
The CDC has described the new initiative as a way to build a research cohort capable of supporting future studies.
That word, “future,” may be the most important part.
Researchers may discover that some health effects are relatively minor. They may find that some conditions are more common than expected. They may discover that certain exposures matter more than others.
They may also discover things nobody anticipated.
That is the nature of scientific research.
9/11 Did Not End on September 11th
America will spend this week remembering the nearly 3,000 people who were killed on September 11, 2001.
That remembrance is necessary.
But there is another part of the story that deserves attention.
Thousands of people who were children at the time of the attacks have spent the past 25 years growing older while researchers have tried to understand what exposure to the World Trade Center disaster might mean for their health.
Some already know the answer.
Others may not.
The new federal study cannot change what happened to them. It cannot turn back the clock or undo the exposure they experienced as children.
What it can do is make sure that their experiences are not lost.
And if the research produces information that helps doctors and public health officials protect children after the next major disaster, then the knowledge gained from September 11th could serve a purpose far beyond remembering the past.
Twenty-five years later, America is still learning what happened that day.
For some of the children who were there, the answer may only now be coming into focus.
—Greg Collier
