Scientists find strong link between severity of exposure at Ground Zero, lung cancer

Researchers hypothesized soon after the Sept. 11, 2001, World Trade Center attacks that responders’ exposure to airborne toxic particles, including known carcinogens, could be harmful to their lungs.

Conclusively linking exposure to lung cancers, though, was difficult, partly because those cancers can take decades to develop. Some work has actually shown a low incidence of lung cancer for responders relative to the general population, which researchers say may be due to the responders’ lower smoking rates.

But scientists with the WTC Health and Wellness Program at Stony Brook University say that, for the first time, they have uncovered a strong association between the severity of exposure and the incidence of lung cancer. A paper published Thursday in JAMA Network Open suggests that police, firefighters, construction workers and others whose jobs on or near the Ground Zero pile made them the most exposed responders developed lung cancers at three times the rate of those who were least exposed, such as those who worked part of the time off-site or whose jobs did not involve excavation, even after correcting for demographic factors and smoking.

“We’re starting to be in the window in which lung cancers will develop,” said Sean Clouston, a Stony Brook University epidemiologist who was the paper’s lead author. “There may be cancers coming in now that will help us to better understand what’s happening to these responders. We certainly haven’t seen the end of it.”

The study, which followed 12,334 responders receiving health care at Stony Brook’s two Long Island clinics for WTC patients from 2012 to 2023, found that 118 lung cancers were diagnosed in that group.

An estimated 400,000 people were exposed to contaminants after the attacks, according to the Centers for Disease Control and Prevention. In lower Manhattan, the plane crashes that resulted in the collapse of the Twin Towers created dust clouds that covered city blocks with ash, debris and particles, including asbestos, silica, metals, concrete and glass. Fires in the debris pile and at WTC 7, which also collapsed, burned through December 2001, with flare-ups through 2002.

Prior research focused on responders’ arrival date at the pile and on their exposure to the dust clouds, an approach that experts say may not adequately account for exposure to fine particulate matter. Because of its size, this material, 2.5 microns or less in diameter, penetrates deep into the lung alveoli and even the bloodstream, making it a significant risk factor for lung cancer. Some responders’ work, such as excavation, would have thrown significant quantities of this material into the air, where it would have lingered for an extended time, invisible to the naked eye, Clouston said.

Clouston and his fellow researchers developed a nuanced exposure severity index by sifting responders‘ answers to questionnaires administered after exposure ended in 2002 for specific exposure activities, sites, smells, hygiene and use of personal protective equipment. They divided their pool of responders into three groups by degree of exposure.

Beyond their central findings on risk and exposure, the researchers found that practices like changing clothes or wearing a hooded protective suit over work clothes were associated with reduced incidence of lung cancer. Some experiences, like working for at least 500 hours in areas that smelled of sewage, were associated with increased incidence — probably not, researchers surmised, because of the sewage itself, but because environments where responders encountered those smells were likelier than others to be fouled by dust or chemicals, or because the responders who detected those smells could do so because they were not wearing protective masks effectively.

Dr. Jacqueline Moline, a Northwell Health epidemiologist and former principal investigator for the World Trade Center Medical Monitoring and Treatment Program at Mount Sinai School of Medicine, who was not involved in the research, said Clouston and his colleagues had made a significant advance by confirming scientists’ early hypotheses about responders’ risk of lung cancer.

The “exposure matrix” they developed is also significant, she said. Cancer screening for survivors and responders now focuses on those who are smokers or former smokers, she said, but it may be “time to reconsider whether we should advocate for screening for high-exposure individuals.”