Occupational noise and age: A longitudinal study of hearing sensitivity as a function of noise exposure and age in South African gold mine workers

Abstract

Background: A relationship exists between occupational noise exposure and age, which remains poorly understood. Objectives:The aim of this study was to establish the relationship between hearing loss and age over time.Method: Audiological data from 2583 mine workers in South Africa were utilised. Data were received from a non-noise exposed group (NNEG) (n = 951) and a noise exposed group (NEG) (≥85 dBA) (n = 1632). Data comprised a low-frequency average (LFA512) (average of audiological thresholds for 0.5 kHz, 1 kHz and 2 kHz) and high-frequency average (HFA346) (average of audiological thresholds for 3 kHz, 4 kHz and 6 kHz). Data were compared by using mixed-effects regression analysis.Results: Base threshold values were higher for the NEG than for the NNEG across frequencies. All year-to-year increases in mean hearing thresholds were statistically significant (p < 0.01). When correcting for age, increases in mean hearing thresholds were higher for the NEG than for the NNEG for HFA346 (3.5 dB vs. 2.9 dB decline over a 4-year period) but similar for LFA512 (0.6 dB vs. 0.7 dB decline). Uncorrected for age, increases in mean hearing thresholds were higher than when age was corrected for. Conclusion:Age and occupational noise exposure influence hearing thresholds over time. The continued increase in hearing thresholds of the NEG above that of the NNEG can be related to ineffective noise management programmes and/or the fact that early noise exposure leads to a higher burden of hearing loss over time -even after noise exposure had stopped.

An overview of occupational noise-induced hearing loss among workers: epidemiology, pathogenesis, and preventive measures

“…The age groups from 30-44 and 45-59 years are at higher risk when exposed to occupational noise, corresponding to the ages of peak labor force participation [ 67 ]. A previous study showed that the affected fraction decreased by age group after 30-44 years old [ 1 ], indicating the heavy impact of occupational noise on the burden of hearing loss at younger ages [ 1 – 3 ].…”

Occupational Hearing Loss for Platinum Miners in South Africa: A Case Study of Data Sharing Practices and Ethical Challenges in the Mining Industry

“…Miners’ PLH scores can be influenced by these ear- and hearing-related risk factors (tuberculosis, HIV, otitis media, otitis externa, impacted cerumen, and their treatments) [ 22 , 23 ], which may not have been taken into consideration when assessing hearing deterioration and planning ONIHL prevention strategies. While the exclusion of miners’ medical information from the audiometry surveillance records may be based on maintaining the confidentiality of medical records and adhering to the mine’s privacy policies, it hinders efforts to prevent ONIHL [ 16 , 19 , 23 ].…”

“…Silo reporting (referring to the reluctance to share information with others from different divisions) [ 18 ] of risks associated with ONIHL may impede efforts directed towards the prediction and prevention of ONIHL. There are factors, other than noise, that are associated with hearing loss [ 8 , 19 ], such as ageing, being male and black, genetic predisposition, exposure to recreational noise [ 19 ], and treatments for tuberculosis and HIV [ 19 , 20 , 21 , 22 , 23 ]. Exposure to chemicals (nitrogen sulphide and carbon monoxide) emitted during some mining processes have also been reported to increase the risk of hearing loss, but research on this is limited in the South African mining industry [ 24 ].…”

“…Exposure to chemicals (nitrogen sulphide and carbon monoxide) emitted during some mining processes have also been reported to increase the risk of hearing loss, but research on this is limited in the South African mining industry [ 24 ]. Studies using miners’ HCP records have shown that data on common medical conditions (tuberculosis, cancer and HIV) and treatments thereof [ 22 ], as well as data on occupational exposures (dust and chemicals) that are associated with ONIHL, are often kept separately from HCP data [ 16 , 19 ].…”

Evaluation of the Impact of Noise Pollution on the Workers of the Bottling Line of the Limited Company of Breweries of Guinea (SOBRAGUI)

“…It is estimated that 80% of people with occupational hearing loss live in low- and middle-income countries and that almost half of the industrial workforce is exposed to hazardous occupational noise. Ninety percent (90%) work in areas where noise levels exceed 85 decibels on average [ 11 ].…”