Within 7 years of the September 11, 2001 terrorist attacks, World Trade Center rescue and recovery workers had a 15% increased risk of cancer, according to a recently released report.1 Higher-than-expected incidences of cancer, particularly of thyroid cancer, prostate cancer, combined hematopoietic and lymphoid cancers, and soft tissue cancers were found.
The study, based on health records and tumor registries from 2001 to 2008, was conducted by the Mt. Sinai Hospital World Trade Center Health Program and included 20,984 police officers, firefighters, rescue workers, construction workers, and others who worked at the site. Forty-three percent of responders were exposed to the dust cloud caused by the buildings’ collapse and the average duration of service at the site was 57 days.
Overall, there were 575 cases of cancer in the study cohort, whereas 499 cases would be expected in a similarly-sized cohort of the general population. Among the rescue and recovery workers, the incidence of thyroid cancer was 239% higher and the incidence of soft tissue cancer was 226% higher than would be expected in a general population cohort. There was a 36% increased risk of hematopoietic and lymphoid cancers and a 21% increased risk of prostate cancer. Increases, though non-significant, were also found in the incidences of non-Hodgkin’s lymphoma and kidney cancer.
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Workers at the site were exposed to a complex mixture of toxic chemicals, including many known and suspected carcinogens such as heavy metals, benzene, asbestos, silica, and glass fibers. Workers who were exposed to the dust cloud and those who worked on the debris pile and had high exposure to dust had an increased cancer risk compared with other workers who were not exposed. Cancer risk was also higher in protective services workers (eg, law enforcement, emergency medical service workers) and in cleaning, maintenance, and electrical/telecommunications workers than in others who participated in the rescue and recovery.
Philip Landrigan, MD, MSc, FAAP, a co-author of the study, said, “Previous studies have looked at cancer incidence rates after September 11, but did not report on associations according to levels of exposure. This study is significant because for the first time it examines associations between several types of cancers in a specific population—WTC rescue and recovery workers—and levels of exposure to the dust on the debris pile in lower Manhattan.”
In an earlier study of New York City firefighters, those who were exposed to the World Trade Center site had a modest 10% increase in cancer incidence compared with firefighters not exposed to the site.2 A comparison of rescue workers with New York State residents not exposed to the site also showed an increased incidence of prostate cancer, thyroid cancer, and multiple myeloma.3
The authors of the Mt. Sinai study warn that the results should be interpreted with caution because of the short follow-up since the 9/11 attacks, the long latency period of most cancers, and the small numbers of observed and expected cases of several types of cancer. In addition, increased medical surveillance may have contributed to the excess cancer incidence.
Most occupational cancers are not diagnosed until 10 or more years after exposure to carcinogens, therefore continued monitoring of World Trade Center rescue and recovery workers may reveal even higher levels of cancer risk.
References
1. Solan S, Wallenstein S, Shapiro M, et al. Cancer in World Trade Center Rescue and Recovery Workers, 2001 to 2008. Environ Health Perspec . doi:10.1289/ehp.1205894.
2. Zeig-Owens R, Webber MP, Hall CB, et al. Early assessment of cancer outcomes in New York City firefighters after the 9/11 attacks: an observational cohort study. Lancet. 2011;378:898-905.
3. Li J, Cone JE, Kahn AR, et al. Association between World Trade Center exposure and excess cancer risk. JAMA. 2012;308:2479-88.
