Mortality among Fire Department of the City of New York Rescue and Recovery Workers Exposed to the World Trade Center Disaster, 2001–2017

Abstract

The World Trade Center (WTC) attacks on 9/11/2001 have consistently been associated with elevated rates of physical and mental health morbidities, while evidence about mortality has been limited. We examined mortality between 9/12/2001 and 12/31/2017 among 15,431 WTC-exposed Fire Department of the City of New York (FDNY) firefighters and emergency medical service providers (EMS), specifically assessing associations between intensity of WTC-exposure and mortality risk. Standardized mortality ratios (SMR) and 95% confidence intervals (CI) compared FDNY cohort mortality with the US general population using life table analysis. Deaths were identified via linkage to the National Death Index. Cox proportional hazards regression models were used to identify associations between intensity of WTC-exposure and mortality, accounting for age, sex, race/ethnicity, smoking history, and other relevant confounders. We identified 546 deaths and a lower than expected all-cause mortality rate (SMR = 0.22; 95% CI, 0.20–0.24). No cause-specific SMRs were meaningfully elevated. Mortality hazard ratios showed no association or linear trend with level of WTC-exposure. Our results provide evidence of the healthy worker effect, despite exposure to the World Trade Center. More follow-up time may be needed to assess the full impact of WTC-exposure on mortality in this occupational population.

Application of Standardized Proportional Mortality Ratio to the Assessment of Health Risk in Relatively Healthy Populations: Using a Study of Cancer Risk in Telecommunication Workers with Excess Exposure to Acid Mists as an Example

“…In the 1980s, several studies on steel workers observed increased risks of laryngeal cancer in those who were exposed to acid mists, mainly sulfuric acid from pickling operations [ 5 , 10 , 11 , 12 ]. The result was later confirmed by studies on other steel workers [ 9 , 13 ], as well as other workers with exposure to acid mists from other manufacturing process [ 14 ].…”

“…The SMR for all causes combined of the study cohort was significantly smaller than 1 ( p = 0.01), which indicated a healthy worker effect, because the overall mortality of the cohort members was lower than the general population of the same sex and age group in Taiwan [ 10 ]. Such a health worker effect is common in studies on occupational cohorts and may be introduced by various causes.…”

All-cause and cause-specific mortality in a cohort of WTC-exposed and non-WTC-exposed firefighters

“…The increased risk of these and other chronic illnesses in WTC-exposed rescue/recovery workers has not resulted in elevated mortality rates, however, when compared with general populations. Studies conducted in three different WTC rescue/recovery worker cohorts and, most recently, in a large combined cohort of WTC rescue/recovery workers showed significantly lower than expected mortality among participants compared with USA, New York State and New York City populations 10–13. These findings may reflect healthy worker effects, a phenomenon in which workers experience better health outcomes than the general population because they were healthier at the time of their employment 14.…”

9/11 Health Update

“…Colbeth et al [ 7 ] studied the mortality among Fire Department of New York City rescue and recovery workers. The researchers used NIOSH’s Life Table Analysis System to generate Standardized Mortality Ratios with the US general population as the comparison group.…”