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Original Investigation
March 18, 2021

Exposure to Cadmium, Lead, and Tobacco Smoke and the 10-Year Cumulative Incidence of Olfactory Impairment: The Beaver Dam Offspring Study

Author Affiliations
  • 1Department of Ophthalmology and Visual Sciences, School of Medicine and Public Health, University of Wisconsin-Madison
  • 2Department of Population Health Sciences, School of Medicine and Public Health, University of Wisconsin-Madison
JAMA Otolaryngol Head Neck Surg. Published online March 18, 2021. doi:10.1001/jamaoto.2021.0079
Key Points

Question  What environmental exposures are associated with the 10-year cumulative incidence of olfactory impairment?

Findings  In this longitudinal cohort study including 2312 individuals, the overall incidence of olfactory impairment was low, but rates increased with age. Participants with higher levels of blood cadmium or high tobacco smoke exposure, as a current smoker or from environmental tobacco smoke, were at an increased risk of developing olfactory impairment.

Meaning  Modifiable environmental exposures may contribute to olfactory impairment that occurs with aging.

Abstract

Importance  Olfactory impairment is common in older adults. Identification of modifiable risk factors for olfactory impairment at midlife has the potential to reduce the burden of olfactory impairment at older ages.

Objective  To determine the 10-year cumulative incidence of olfactory impairment and evaluate potentially modifiable risk factors for impairment including exposure to cadmium, lead, and tobacco smoke.

Design, Setting, and Participants  Data from the Beaver Dam Offspring Study, a longitudinal cohort study of sensory health and aging in a general population, were available from examinations at baseline (2005-2008), 5 years (2010-2013), and 10 (2015-2017) years. A total of 2312 participants without olfactory impairment at baseline and with olfaction data available at the 5- and/or 10-year examination were included. The present study was conducted from April 28, 2020, to January 8, 2021.

Main Outcomes and Measures  Olfactory impairment was measured by the San Diego Odor Identification Test. Cox discrete-time proportional hazards analyses were used to model associations between baseline covariates, including blood cadmium and lead levels and tobacco smoke exposure, and the 10-year cumulative incidence of olfactory impairment.

Results  Of the 2312 participants, 1269 (54.9%) were women; mean age was 49 years (range, 22-84 years) at baseline. The 10-year cumulative incidence of olfactory impairment was 4.6% (95% CI, 3.7%-5.6%) and increased with age. Because of high collinearity, cadmium and tobacco smoke exposure were modeled separately. In a multivariable adjusted model, higher blood cadmium level (hazard ratio [HR], 1.70; 95% CI, 1.05-2.74) was associated with the 10-year cumulative incidence of olfactory impairment. Substituting tobacco smoke exposure for cadmium in the model, high exposure to tobacco smoke as a current smoker (HR, 2.94; 95% CI, 1.63-5.29, smoker vs no exposure) or from environmental tobacco smoke (HR, 2.65; 95% CI, 1.24-5.63, high vs no exposure) was also associated with an increased risk for developing olfactory impairment. Blood lead levels were not associated with olfactory impairment.

Conclusions and Relevance  Results of this longitudinal cohort study suggest that modifiable environmental exposures may contribute to olfactory impairment that occurs with aging. Identification of modifiable risk factors for olfactory impairment may lead to prevention strategies that have the potential to reduce the burden of olfactory impairment at older ages.

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