Twenty-five years after the September 11 attacks, the health consequences for people exposed to the World Trade Center disaster are still unfolding. Cancer has become an increasingly significant concern, with thousands of survivors now receiving treatment through the World Trade Center Health Program.
The 9/11 cancer cases emerging today are occurring decades after people were exposed to the dust and smoke that covered Lower Manhattan following the collapse of the World Trade Center towers.
Toxic Dust Exposed Thousands
When the towers fell in 2001, enormous clouds of dust spread through Lower Manhattan. The material entered nearby buildings through broken windows and ventilation systems and settled on furniture, carpets and other surfaces.
The dust contained pulverized construction materials, products from burning jet fuel and heavy metals including cadmium, lead and mercury. The Centers for Disease Control and Prevention estimates that as many as 400,000 people may have been exposed.
Those affected included firefighters and paramedics, but exposure was not limited to emergency workers. People who lived, worked or attended school near the World Trade Center also encountered the contaminated environment.
Cancer Diagnoses Have Increased
Data from the World Trade Center Health Program show a major increase in cancer among people affected by the attacks. About half of the roughly 54,000 survivors receiving financial assistance through the program have now been diagnosed with cancer, around three times the number recorded five years ago.
Age is an important factor because cancer becomes more common as people grow older. However, researchers have also found indications that certain illnesses among survivors may be associated with their exposure to the toxic dust.
That has increased attention on the long-term effects of the disaster and the growing number of 9/11 cancer cases.
Mesothelioma Raises Concern
Researchers are particularly interested in rare cancers such as mesothelioma. The disease is strongly associated with asbestos exposure, and asbestos was among the hazardous materials present at the World Trade Center site.
According to researchers involved in studying the affected population, mesothelioma has appeared among World Trade Center Health Program participants at a higher rate than expected in the general population.
The cancer is also notable because it can take decades to develop after exposure. That long delay means some health experts believe current cases may not represent the full future impact of the exposure.
Survivors Continue Seeking Care
Medical centers treating people exposed after the attacks continue to receive new patients. One New York treatment program reported seeing approximately 120 new patients each month.
Enrollment has also shifted over time. While first responders initially represented a larger share of new participants, people who lived, worked or attended school around Ground Zero have increasingly joined the program.
In 2024 and 2025, approximately twice as many survivors enrolled as first responders, according to CDC data.
A Health Crisis That Has Lasted Decades
The continuing increase in 9/11 cancer cases highlights how the health effects of the attacks did not end when the debris was cleared from Lower Manhattan. Some conditions appeared relatively soon after the disaster, while others have taken decades to emerge.
The World Trade Center Health Program now provides medical monitoring and treatment for nearly 150,000 members across the United States and its territories.
As survivors continue to age, researchers and medical providers are monitoring the population closely. The full scale of the long-term health consequences may become clearer only with continued research and follow-up.
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