M.P.H.(Occupational Hygiene), Faculty of Health Sciences, University of the Witwatersrand, 2009 / BACKGROUND
Hearing loss from occupational exposures is a serious and widespread problem in
underground nickel mining. This is a major contributor to compensable illnesses
resulting not only in costly compensation but posing a serious threat to safety and also
reducing the quality of working life.
OBJECTIVES
The objectives of this study were to identify the prevalence of noise induced hearing
loss amongst underground nickel miners with at least 5 years of exposure as well as
describe some risk factors for noise induced hearing loss in this occupational setting.
METHODS
One hundred and sixty eight underground nickel miners, or one hundred percent of
eligible workers’ medical records with baseline and periodic audiograms were
reviewed to identify the prevalence of noise induced hearing loss and also evaluate
some of the risk factors for noise induced hearing loss namely age, duration of
exposure, use of oto-toxic agents, high ambient noise levels, hearing impairment, high
pre-employment noise levels, history of acoustic trauma, history of ear injury and
history of previous military, hunting or police work. One hundred underground mine
workers were interviewed to give insight into their pre-employment noise exposure
history, non-occupational noise exposure, perceived noise levels at work, knowledge
of noise hazards and their control, and the use of hearing protection devices. One
hundred and sixty eight workers were observed in their various tasks over a 14 day
period and their work practices were scored to identify compliance to the use of
hearing protective devices as well as confirm the presence or absence of oto-toxic
agents like heavy metals and solvents. Data were analyzed using the EpiInfo software
version 3.4.3: 1997 as well as the online statistical package Vassar Stats.
RESULTS
A noise induced hearing loss prevalence of 27.4% was identified with 42% being mild
hearing loss, 28.8% moderate hearing loss and 28.8% moderate to severe noise
induced hearing loss. The highest noise induced hearing loss prevalence of 60% was
found in the 50 and above years age group whilst 45.5% was found in the 40 – 49
year age group, 20% in the 30- 39 year age group and 5.3 % in the 20 – 29 year age
group. This difference was statistically significant ( 2
1 = 19 p < 0.001). Age with a 2
= 24, p< 0.002 and duration of exposure with a 2 = 19, p< 0.001 were found to be
major determinants of noise induced hearing loss at the mine. Jackhammer operation
and machine operation were found to be associated with noise induced hearing loss
compared to the other tasks; Tukey’s Honestly Significant Difference 0.05 = 12.23
p<0.01. The following risk factor was found to be related to noise induced hearing
loss: use of quinine OR = 2.16 with CI 95% = 0.12 – 1.72. Ninety seven percent of
the workers confirmed exposure to high noise levels. The knowledge of noise induced
hearing loss at the mine was high (85%). Compliance with the use of hearing
protective devices was found to be low with optimum usage only being achieved
during the last 4 days of the 14 day observation period.
CONCLUSIONS
These findings attest to the relatively high prevalence of noise induced hearing loss at
the mine. It can also be concluded that though the knowledge of noise induced
hearing loss is high, the effective use of hearing protection still needs improvement
through the implementation of comprehensive hearing conservation programs which
adequately screen workers at pre-employment stage as well as consider the workers’ perceived knowledge, attitudes as well as practices in an occupational setting.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:wits/oai:wiredspace.wits.ac.za:10539/7370 |
| Date | 19 October 2009 |
| Creators | Masaka, Edmore |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf, application/pdf |
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