December 18, 2012 | by Shawn Le
The shadows of the former World Trade Center buildings have lingered over the American mindscape since the towers fell in 2001. New fears may be raised by a new study released online Tuesday in the Journal of the American Medical Association reporting an increase in cancer incidence among rescue and recovery workers who worked in the aftermath of the incident. But one cancer expert cautions against undue panic.
The study’s authors, who work for the New York Department of Health and Mental Hygiene, analyzed data from the World Trade Center Health Registry – and found an increased incidence of prostate, thyroid and multiple myeloma cancer cases among rescue and recovery workers compared to the general population of New York state. However, they found no significant difference in the overall cancer rate between the groups.
The New York Department of Health had established the registry in 2002 to monitor the health of people exposed to the disaster and the cloud of toxic dust created by it. More than 55,000 New York City residents enrolled in the registry, of which nearly 22,000 were rescue or recovery workers at Ground Zero. In the new study, researchers analyzed data from the registry and 11 state cancer registries to evaluate the cancer rate among workers at Ground Zero, volunteers in the area, and those with no direct exposure to the area.
The researchers looked at cancers diagnosed between 2007-2008, because those cases would be “most likely to be related to exposure during September 11 and its aftermath.”
Smita Bhatia, M.D., M.P.H., the Ruth Ziegler Chair in Population Sciences at City of Hope, stresses the importance of monitoring the health of this population, saying the only way to fully understand the long-term consequences of toxic-chemical exposure is to continue to follow the people.
“Any time there are major changes in the environment such as the one reported here, the health-care community needs to be sensitized to the adverse consequences,” says Bhatia, “especially among individuals with pre-existing health issues.”
“Our knowledge about how long it can take a cancer to develop after exposure to carcinogens stems from patients developing second cancers related to radiation or chemotherapy treatment,” Bhatia says. “We have learned from atomic bomb survivors that radiation-related cancers usually have a latency of about 10 years.”
As Thomas A. Farley, M.D., M.P.H., the health commissioner in New York City, told the New York Times: “We might see something different 20 years down the line.”
In the recent study, of 1,187 cancer cases that met the researchers' criteria, 439 were diagnosed in rescue and recovery workers, and 748 were among participants not involved in Ground Zero work. Said the authors: “The intensity of World Trade Center exposure was not significantly associated with cancer of the lung, prostate, thyroid, non-Hodgkin lymphoma, or hematological cancer in either group.”
Bhatia says these findings represent preliminary results, and she is not aware of any common genes or carcinogens that link the prostate, thyroid and multiple myeloma cancers. A thorough investigation of what toxic chemicals this group were exposed to would be needed “before the excess cancers reported in the study could be attributed to the event.”