Occupational exposure to disinfectants and asthma incidence in U.S. nurses: A prospective cohort study

Background Exposure to disinfectants among healthcare workers has been associated with respiratory health effects, in particular, asthma. However, most studies are cross‐sectional and the role of disinfectant exposures in asthma development requires longitudinal studies. We investigated the association between occupational exposure to disinfectants and incident asthma in a large cohort of U.S. female nurses. Methods The Nurses’ Health Study II is a prospective cohort of 116 429 female nurses enrolled in 1989. Analyses included 61 539 participants who were still in a nursing job and with no history of asthma in 2009 (baseline; mean age: 55 years). During 277 744 person‐years of follow‐up (2009‐2015), 370 nurses reported incident physician‐diagnosed asthma. Occupational exposure was evaluated by questionnaire and a Job‐Task‐Exposure Matrix (JTEM). We examined the association between disinfectant exposure and subsequent asthma development, adjusted for age, race, ethnicity, smoking status, and body mass index. Results Weekly use of disinfectants to clean surfaces only (23% exposed) or to clean medical instruments (19% exposed) was not associated with incident asthma (adjusted hazard ratio [95% confidence interval] for surfaces, 1.12 [0.87‐1.43]; for instruments, 1.13 [0.87‐1.48]). No association was observed between high‐level exposure to specific disinfectants/cleaning products evaluated by the JTEM (formaldehyde, glutaraldehyde, bleach, hydrogen peroxide, alcohol quats, or enzymatic cleaners) and asthma incidence. Conclusions In a population of late career nurses, we observed no significant association between exposure to disinfectants and asthma incidence. A potential role of disinfectant exposures in asthma development warrants further study among healthcare workers at earlier career stage to limit the healthy worker effect.