Prevalence of Hearing Threshold Shift among Chemical Industrial Workers: A Comparison of NIOSH and OSHA Threshold Shift Criteria

Abstract

The purpose of this study was to compare the prevalence of abnormal hearing tests among workers from 8 chemical industries using NIOSH
and OSHA criteria with or without age correction. This study was conducted in 8 chemical industries in eastern region of Thailand which provided
annual hearing tests by occupational medicine department, Rayong Hospital (2011-2015 AC). Participants with 2 year-consecutive audiograms
were included. First audiogram served as baseline audiogram for annual test interpretation using NIOSH and OSHA criteria. 

Results from the research revealed that prevalence of signifcant threshold shift (NIOSH), standard threshold shift (OSHA), and standard threshold shift with age correction were 22.15-31.91%, 4.83-14.85%, and  2.34-5.29%, respectively. No baseline revisioncaused the rising of prevalence. OSHA criteria with age correction showed possibility of high specifcity, while NIOSH criteria showed possibility of high sensitivity for occupational noise induced hearing loss screening.

The research recommendations for further study were : (1) comparison study to demonstrate sensitivity and specifcity of each criteria; (2)
results of proper baseline revision for signifcant threshold shift and standard threshold shift; and (3) similar studies in other industrial sectors.