ArticlesEarly assessment of cancer outcomes in New York City firefighters after the 9/11 attacks: an observational cohort study
Introduction
The attacks on the World Trade Center (WTC) on Sept 11, 2001 (9/11), created an environmental disaster of unprecedented scale for the New York area, and the potential for occupational exposure to known and suspected carcinogens. Many first responders, including about 12 500 firefighters employed by the Fire Department of the City of New York (FDNY), were exposed to aerosolised dust—an amalgam of pulverised cement, glass fibres, asbestos, lead, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and polychlorinated furans and dioxins produced as combustion byproducts from the collapsed and burning buildings.1 They were also exposed to toxic fumes, initially from burning jet fuel and over the subsequent 10-month recovery effort from diesel fuel from heavy equipment.
The full extent of the association between WTC-exposure and cancer occurrence remains unknown. So far, only one study investigating WTC-related cancer has described eight cases of multiple myeloma in WTC responders, but uncertainty related to the definition of exposure and the exact population at risk limit the generalisability of its conclusions.2 Our study is a preliminary effort to examine incidence of cancers occurring within the first 7 years after 9/11 in a cohort of nearly 10 000 male firefighters with known health information before 9/11 and minimal loss to follow-up.
Section snippets
Study population
The original study population consisted of 10 567 firefighters who were employed by FDNY for at least 18 months, were active firefighters on Jan 1, 1996, and if alive on Sept 12, 2001, also had known WTC-exposure status (WTC-exposed or non-exposed). The Jan 1, 1996, start date was chosen on the basis of completeness of the New York state tumour registry data. We excluded data from 576 firefighters who were or would have been aged 60 years or older on 9/11, because their small number could have
Results
Table 2 shows selected characteristics of the primary analytic cohort. The mean age at first cancer diagnosis was older in the WTC-exposed group (52·5 [SD 6·4] years) than in the non-exposed group (49·9 [SD 8·9] years).
We identified a modest effect of WTC exposure for all cancers combined by comparing the ratios in the exposed group to those in the non-exposed group (table 3). An exposure-response gradient generated with the FDNY exposure categories3 or the common-exposure categories4 was not
Discussion
WTC-exposed firefighters had about 10% higher overall cancer incidence ratios than those expected in a similar demographic mix from the general male population in the USA and about 32% higher than in non-exposed firefighters (panel). We identified these differences in our primary analysis in which we compared only first cancers in the FDNY cohort with all tumours reported in SEER reference rates. Additional analyses consistently showed similar modest increases in all cancer sites combined for
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