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Cancer Risk and Ground Zero Exposures: The Early Evidence

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Timothy S. Paul
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The Biggest Study to Date Finds Little Evidence of Elevated Rates of Cancer, But Researchers Stress That It's Still Early to Tell

The collapse of the Twin Towers on September 11, 2001, exposed hundreds of thousands of survivors to dust, debris, and fumes containing known and suspected carcinogens, including asbestos, silica dusts, polycyclic aromatic hydrocarbons, benzene, and metals such as arsenic and cadmium.

Many feared a resulting spike in cancers. But so far, the number of cancers among people living or working near Ground Zero has been in line with the general population, according to a new study by Mailman School faculty member Steven Stellman, PhD, MPH, and co-authors at the New York City Department of Health and Mental Hygiene. The researchers did, however, find higher rates of three types of cancer among first responders.

The paper, published in December 19 edition of The Journal of the American Medical Association, is the largest study to date of cancer among 9-11 survivors.

The researchers looked at 23 types of cancer in 55,778 people answering World Trade Center Health Registry surveys from 2003 to 2008. Among rescue and recovery workers, they found elevated rates of thyroid cancer, prostate cancer, and multiple myeloma, although the role of September 11th exposures is uncertain.

Thyroid cancer is linked to radiation exposure, but there have been no documented or suspected carcinogenic levels of radiation at the site. While prostate cancer has been suspected to have linkages to environmental exposures, there has been no conclusive evidence to support the assertion.

More intriguing are the higher levels of multiple myeloma, which has been linked to occupational exposures, including firefighting and benzene. Blood cancers have a short latency period, which means these cancers develop sooner than solid tumor cancers like lung or breast cancer. The elevated rate, although based only seven cases, could presage emergence of other cancers in the future.  

"The operative phrase is, it’s early. The majority of cancers take a very long time to develop from exposure to environmental toxins. It can take decades," says Dr. Stellman, professor of Clinical Epidemiology and the senior author of the study.

New York City Health Commissioner Thomas Farley made a similar point in an interview about the study with The New York Times: “Cancers take 20 years to develop, and we might see something different 20 years down the line.”

Much remains to be seen. For now, the government is playing it safe. In June, John Howard, director of the National Institute for Occupational Safety and Health, ruled that cancer could be added to the list of sicknesses covered by the $4.3 billion World Trade Center fund.