Advanced noise-induced deafness among workers in Singapore-What has changed?

Abstract

Context: Noise-induced deafness (NID) contributes a significant disease burden internationally, and is a leading occupational disease in Singapore. Aims: This study profiles the epidemiological characteristics of advanced noise-induced deafness (NID(A)) cases and explores whether these have evolved with time. Settings and Design: A quantitative retrospective analysis of prior NID(A) cases was performed. National records of NID(A) cases from 2001 to 2010 were obtained, with permission from the Ministry of Manpower, consisting of worker audiograms, case records, and noise monitoring reports. Methods and Material: Comparison was made with data from a prior study (127 cases, 1985-1994) to identify shifts in NID(A) epidemiology; 71 out of 73 NID(A) case records (2001-2010) from the national data were reviewed. Statistical Analysis Used: Statistical Package for Social Sciences (IBM) was used for statistical analysis. Results: Mean noise exposure (24-29.6 years) and age at diagnosis (48-54.6 years) have risen. Total case numbers (127 to 73 cases), average hearing loss levels (61.5 to 56.0 A-weighted decibels), and delayed reporting of NID(A) cases (82.7% to 47.9%) have decreased. Metal manufacturing and marine industries remain top contributors (69.1%, from 68.5%); 31% were noncompliant with hearing protector (personal protective equipment, PPE) use and 38% did not use PPE properly. Conclusions: NID(A) case profiles have shifted over time, with reduced case numbers, lower hearing loss levels at diagnosis, and earlier case notification, possibly linked to improvements in legislative coverage and NID prevention programs. Changes in age and average duration of noise exposure may be related to these improvements. Early case notification, PPE compliance, and proper usage should be focus areas for NID prevention and hearing conservation programs.