Environmental Cadmium and Lead Exposures and Hearing Loss in U.S. Adults: The National Health and Nutrition Examination Survey, 1999 to 2004

Yoon-Hyeong Choi,¹ Howard Hu,^1,2 Bhramar Mukherjee,³ Josef Miller,⁴ and Sung Kyun Park^1,2

¹Department of Environmental Health Sciences, ²Department of Epidemiology, and ³Department of Biostatistics, University of Michigan School of Public Health, Ann Arbor, Michigan, USA; ⁴Department of Otolaryngology, University of Michigan Medical School, Ann Arbor, Michigan, USA


Abstract

Background: Although cadmium and lead are known risk factors for hearing loss in animal ­models, few epidemiologic studies have been conducted on their associations with hearing ability in the general population.


Objectives: We investigated the associations between blood cadmium and lead exposure and hearing loss in the U.S. general population while controlling for noise and other major risk factors contributing to hearing loss.


Methods: We analyzed data from 3,698 U.S. adults 20–69 years of age who had been randomly assigned to the National Health and Nutrition Examination Survey (NHANES) 1999–2004 Audiometry Examination Component. Pure-tone averages (PTA) of hearing thresholds at frequencies of 0.5, 1, 2, and 4 kHz were computed, and hearing loss was defined as a PTA > 25 dB in either ear.


Results: The weighted geometric means of blood cadmium and lead were 0.40 [95% confidence interval (CI): 0.39. 0.42] µg/L and 1.54 (95% CI: 1.49, 1.60) µg/dL, respectively. After adjusting for sociodemographic and clinical risk factors and exposure to occupational and nonoccupational noise, the highest (vs. lowest) quintiles of cadmium and lead were associated with 13.8% (95% CI: 4.6%, 23.8%) and 18.6% (95% CI: 7.4%, 31.1%) increases in PTA, respectively (p-trends < 0.05).


Conclusions: Our results suggest that low-level exposure to cadmium and lead found in the general U.S. population may be important risk factors for hearing loss. The findings support efforts to reduce environmental cadmium and lead exposures.


Key words: cadmium, epidemiology, hearing, lead, NHANES. 


Environ Health Perspect 120:1544–1550 (2012). http://dx.doi.org/10.1289/ehp.1104863 [Online 31 July 2012]


Address correspondence to S.K. Park, SPH II-M5541, Departments of Epidemiology and Environmental Health Sciences, University of Michigan School of Public Health, 1415 Washington Heights, Ann Arbor, MI 48109 USA. Telephone: (734) 936-1719. Fax: (734) 936-2084. E-mail: sungkyun@umich.edu


Supplemental Material is available online (http://dx.doi.org/10.1289/ehp.1104863).


This study was supported by grant K01-ES016587 from the National Institute of Environmental Health Sciences. This research was also supported, in part, by a pilot project research training grant (T42-OH008455) from the Center for Occupational Health and Safety Engineering at the University of Michigan. The contents of this paper are solely the responsibility of the authors. 


The authors declare they have no actual or potential competing financial interests.


Received 16 December 2011; Accepted 31 July 2012; Online 31 July 2012.