The September 11 cancer wave ahead

Smoke rises from the rubble of the World Trade Center in September 2001, as crews search for survivors and victims from the terror attacks two days earlier.

After the collapse came the dust. It billowed across Lower Manhattan in the wake of the 2001 World Trade Center terror attacks, turning people into ghosts as they trudged to safety.

It blew into buildings through broken windows and air intakes, settling into carpets, curtains and upholstery and leaving a fine powder on surfaces. People wrote messages in the dust coating the windows of buildings.

Despite official assurances at the time, the dust was toxic — loaded with finely pulverized building materials, as well as the byproducts of jet fuel combustion and vaporized heavy metals like cadmium, lead and mercury.

The U.S. Centers for Disease Control and Prevention estimates that as many as 400,000 people were exposed. Some were first responders like firefighters and paramedics, but others were put in harm’s way because they returned to contaminated apartments, schools and offices in Lower Manhattan or Brooklyn, where they breathed in contaminants.

As a result, more people have now died of environmental illnesses that followed the September 11 attacks than perished during the collapse of the towers that day.

Over the past 25 years, the mix of problems experienced by September 11 survivors has changed, too. About half of the 54,000 survivors who have qualified for financial help through the World Trade Center Health Program now have cancer, roughly triple the number who had the same diagnosis five years ago, according to CDC data.

The likelihood that a person will get cancer increases with age, so it’s not surprising that people who lived through the World Trade Center attacks would be more likely to get cancer 25 years later. But there are signs that some of these cancers are linked to the toxic dust people were breathing for months after the attacks, and aren’t just a factor of aging. Rare “sentinel cancers” such as mesothelioma are beginning to show up in World Trade Center survivors, and they appear to be more prevalent than in the general population.

“This is one of the largest man-made disasters in the history of United States,” said Dr. Alan Arslan, a cancer epidemiologist at NYU Langone Medical Center who studies September 11 survivors. “And it is also a disaster characterized by a very complex exposure to many, many potential carcinogens, including asbestos.”

Dr. Leigh Wilson, who directs the World Trade Center Environmental Center — one of seven clinical centres of excellence in the New York area that treat people exposed after the World Trade Center disaster — and works with Arslan, said their program continues to receive about 120 new patients each month.

Enrollment is picking up as people realize they qualify for care. When the program was launched in 2012, more first responders signed up than “survivors”: people who lived, worked or went to school within a certain area around ground zero. But over time, the number of new survivor enrollments each year has outpaced those of first responders. Roughly twice as many survivors as first responders enrolled in the program in 2024 and 2025, according to CDC data.

“I think it’s very well understood that [first] responders are eligible for the World Trade Center Health Program, but a lot of survivors don’t realize that they are eligible,” Wilson said.

A rare and deadly cancer increases in 9/11 survivors

One of the chief concerns in the wake of the tragedy was the hundreds of tons of asbestos that had been used as a fireproofing material in one of the towers and blasted free in the attacks.

Asbestos has tiny needle-like fibers that burrow deep into tissue, creating chronic inflammation that spurs the development of cancers of the lungs, voice box and ovaries. It also causes a rare and aggressive cancer called mesothelioma, or cancer of the mesothelium, the thin layer of tissue that protects internal organs like the lungs and abdomen.

Mesothelioma is what’s known as a sentinel cancer. Almost always, when doctors diagnose it, they also know exactly how how it happened: through exposure to asbestos. Very few cancers have ever been so closely linked to an environmental agent.

Still, exposure doesn’t guarantee a person will get mesothelioma. Somewhere between 1 in 8 and 1 in 13 people who are heavily exposed to asbestos on the job will develop the cancer later in life. And mesothelioma isn’t the only way asbestos makes people sick; it can also cause lung cancer and progressive scarring of the lungs called asbestosis.

But mesothelioma does offer cancer researchers one of the clearest pictures they have of cause and effect. Many chemical exposures, for example, have been linked to breast and prostate cancers, cancers that are also prevalent in World Trade Center survivors, but so are lifestyle factors and genes, making it a thorny problem to tease out the cause of any one person’s cancer after an environmental disaster. Not so with mesothelioma.

Because of this, researchers see it as a kind of harbinger.

“Rates are only going to go up,” said Dr. Jacqueline Moline, who directs the World Trade Center Health Program at Northwell Health. “This will be a foreshadowing” of the cancer burden ahead.

Moline says 38 cases of mesothelioma have been diagnosed among the nearly 155,000 people enrolled in the World Trade Center Health Program to date, an incidence that already appears to be about three times as high as in the general population.

And it’s still early. Mesothelioma takes its time to show up, said Dr. Raja Flores, chairman of the department of thoracic surgery at Mount Sinai Health System, who has pioneered treatments for the disease.

“I think what we’re seeing now is actually the beginning. The latency period for mesothelioma can be 25 to 50 years,” he said. It’s not the most common cancer showing up after the World Trade Center attacks, but “mesothelioma is a very important one because it’s practically a death sentence for most people.”

How ordinary people were exposed

For one of the residents enrolled in the survivor group, a man who was 23 at the time of the attacks, it took 15 years.

The man lived a few blocks from the World Trade Center. He told investigators he was exposed to the large dust cloud on September 11. He left his apartment for a week after the attacks, and he came home to a light coating of dust on its surfaces. He cleaned up the dust but never had his space professionally cleaned.

He remembered World Trade Center dust being present in his apartment for more than a month after the attacks. He saw it in the air every day for months.

Aside from living close to the Twin Towers, the man appeared to have no other risk factors. He didn’t smoke and wasn’t overweight.

In 2012, the man began to have abdominal pain and bloating. Four years later, when doctors performed a minimally invasive procedure to repair what they suspected was a hernia, they found something else.

He was diagnosed in 2016, at age 38, with mesothelioma of his abdominal wall. He had aggressive surgery to cut out the tumors and “hot wash” chemotherapy, in which doctors filled his abdominal cavity with warmed cancer-killing medications to destroy any microscopic tumors that remained.

His case was among four described in a study of mesothelioma in World Trade Center survivors in 2024. He responded well to the treatment and was still alive when the report was published. Two of the four patients had died of their cancers, however.

In a December 2001 memo included among the newly released documents, Cate Jenkins, an environmental scientist in the Waste Identification Branch at the U.S. Environmental Protection Agency, did some rough calculations of the risk people might face from living or working near the Twin Towers after September 11.

In a scenario eerily like the actual case described by the World Trade Center Health Program, Jenkins calculated the increased risk to a person who was enveloped by the initial dust cloud walking back to their apartment in Lower Manhattan and who left for a few days after but came back and tried to clean their own apartment.

In that case, she wrote, the increased risk of getting mesothelioma would be 1 in 100, about 100 times above the EPA’s acceptable threshold for cancer risk from an environmental exposure. If the person continued to live in that apartment for the next 15 years, their risk for mesothelioma would rise to 1 in 10, which is 1,000 times above the EPA’s threshold.

New documents highlight flawed testing and communication

Jenkins’ memo was part of a cache of new documents made public last week by New York City officials in response to two Freedom of Information Act lawsuits filed by the 9/11 Health Watch advocacy group.

Even as internal discussions were sounding the alarm, health officials were making reassuring statements to the public.

In a statement issued a week after the attacks, EPA Administrator Christine Whitman said that air testing in New York and Washington showed that people in those areas were not being exposed to “excessive levels of asbestos or other harmful substances.”

“Given the scope of the tragedy last week, I am glad to reassure the people of New York and Washington DC that their air is safe to breathe, and their water is safe to drink,” Whitman was said a news release. It was only one of many repeated assurances to people who were living or working near the site.

Fifteen years later, Whitman apologized in media interviews. “I’m very sorry that people are sick,” she told the Guardian. “I’m very sorry that people are dying, and if the EPA and I in any way contributed to that, I’m sorry. We did the very best we could at the time with the knowledge we had.”

Investigations later showed that these statements were based on flawed testing.

Early on, the EPA was primarily focused on asbestos levels in outdoor air and didn’t test inside many buildings, where pollutants can concentrate and become trapped, resulting in higher exposures.

The agency also relied on testing thresholds for asbestos that were not health-based.

“Asbestos is unsafe at any amount,” said Kimberly Flynn, director of the nonprofit advocacy group 9/11 Environmental Action.

“The EPA said it was safe many, many, many times and said that that declaration of safety was based on science, which it was not,” said Flynn, who is herself a World Trade Center survivor.

As a result, Flynn said, many people simply didn’t realize the danger they were in and didn’t take steps they should have to protect themselves.

Additionally, the agency’s tests relied on a less sensitive optical microscopy method that can see only larger asbestos fibers. The intensity of the World Trade Center collapse created a range of sizes of asbestos fibers, including some that were very small, which were later picked up by a more sensitive technology: transmission electron microscopy.

This testing, which was commissioned by the Ground Zero Elected Officials Task Force, a group started by Rep. Jarrold Nadler, found that levels of asbestos in two apartment buildings near the World Trade Center were “significantly elevated.”

Jenkins, the EPA environmental scientist, later said the scientists, who were asbestos testing experts and EPA contractors, found nine asbestos fibers for every one found by the EPA.

Their report recommended that indoor spaces be cleaned by professionals with experience removing asbestos and that residents not reoccupy those spaces until after they had been cleared.

Instead, New York officials recommended that people clean their own apartments with wet mops and wet rags and if possible with vacuum cleaners with HEPA filters.

Many of these homes were not cleaned using even these minimally protective methods, however, according to a door-to-door survey conducted shortly after the attacks by the New York City Department of Health.

“People went home to poison, while the government that was supposed to protect them looked the other way,” said Linda Reinstein, president and co-founder of the nonprofit Asbestos Disease Awareness Association.

As a result, environmental health specialists believe, residents were probably re-exposed to the toxins in the dust in their own homes for months after the attacks. Anything that could stir up the dust – such as vacuuming the carpet, sweeping the floor, even just tracking it in on their shoes – could stir up the dust again.

“The composition of the World Trade Center material should also have demanded caution,” said Dr. Richard Peltier, a professor of environmental health sciences at the University of Massachusetts at Amherst.

“This was not ordinary urban particulate matter. The collapse pulverized concrete, gypsum wallboard, glass fibers, carpeting, stored chemicals and other building materials. The fires and destruction added metals, asbestos and a complex mixture of combustion products and organic chemicals. In effect, thousands of tons of materials that were never intended to be inhaled were crushed, burned, aerosolized and deposited across a densely populated urban area.

“I think this changes how we should think about September 11. The mortality from the World Trade Center disaster did not end when the buildings fell. The health consequences have continued to accumulate for 25 years.”

Brenda Goodman, CNN