Prevalence of noise induced hearing loss among employees at a mining industry in Zimbabwe

Abstract

Background: Noise induced hearing loss (NIHL) is within the top five occupational illnesses in Zimbabwe. Workers at a mining company complained about loss of hearing at the mine clinic. Objective: To determine the prevalence of NIHL among employees at the Mine. Methods: We conducted a descriptive cross sectional study at the mine. Workers were proportionally selected to represent all the mine departments or working areas. We measured noise levels at various mine sites, conducted a walk-through survey to observe noise related worker practices and conducted audiometric testing. Results: Mean age for workers was 34.8±7.6 years and the mean duration of exposure to noise was 7.5±1.2 years. All workers could define noise. Ninety (53%) workers attributed NIHL to noisy work environment. Excessive noise levels were in Plant Processing (94 dBA), Underground Mining (102 dBA) and (Underground Workshop (103 dBA). Sixty two (36.7%) workers had NIHL. NIHL increased as a function of age (chi square=30.99 df=3 p<0.01) and was associated with work area (chi square=24.96 df=5 p<0.01). Observed workers took heed of noise warnings. There was no documented hearing conservation program at the mine. Conclusion: The prevalence of NIHL of 37% is high. Age and work area were associated with NIHL. Studies reported that age tends to distort the relationship between noise exposure and NIHL. Mine management should institute a hearing conservation program to protect employees against hazardous noise. Management may meanwhile use administrative controls and adhere to permissible exposure limits according to the noise regulations.

Community Regulation in Noise Control Towards Less Noise City

“…The following programs of effective HCP include noise monitoring, engineering control, administrative control, worker education, selection, and use of Hearing Protection devices (HPDs), and periodic audiometric evaluations. HPDs should be able to reduce worker exposure to tolerable noise or permissible exposure level (PEL) [12].…”

Occupational Noise Exposure and Hearing Impairment among Spinning Workers in Iran

“…In fact, chronic exposure results in metabolic changes in cochlear hair cells and capillary vasoconstriction. Hearing loss, caused by exposure to high levels of occupational noise, depends on the duration of exposure, noise characteristics, and the individual's susceptibility (11)(12)(13). However, with respect to the reversibility of NIHL, the available data supporting the role of demographic factors are inconclusive (14).…”

A proposed preliminary model for monitoring hearing conservation programmes in the mining sector in South Africa

“…A review of literature on the management of ONIHL in the mining sector shows that hearing conservation programmes (HCPs) are the most effective way of managing excessive exposure to hazardous noise in the workplace (Amedofu, 2007;Feuerstein, 2001;Chadambuka, Mususa, and Muteti, 2013;Moroe, 2018). This is particularly so for the hierarchy of control, which if implemented correctly is reported to lead to desired outcomes that include the elimination of noise as depicted in Figure 1.…”

“…Direct costs include compensation costs, costs associated with damage in the workplace, and the cost of interruption of production; while indirect costs include the cost of livelihood lost and loss of income to dependents (Hermanus, 2007). Statistics on the burden of ONIHL in developing countries are not readily available (Nelson et al, 2005); however, Chadambuka, Mususa, and Muteti (2013) argue that 80% of individuals affected by ONIHL reside in low-and middle-income countries where ONIHL presents a 'much heavier burden than in developed regions of the world'.…”