Abstract
Literature into exposure to occupational noise in developing countries suggests that the prevalence of occupational noise–induced hearing loss is still high. There is also evidence that the mining industry is aware of this epidemic; however, the efforts to curb occupational noise–induced hearing loss are currently unsuccessful. Therefore, the aim of this study was to explore and document current evidence reflecting trends in the management of occupational noise–induced hearing loss in the mining industry in Africa from 1994 to 2016. A systematic literature review was conducted in line with the Cochrane collaboration guidelines and Preferred Reporting Items for Systematic Reviews and Meta-Analysis. Electronic bibliographic databases such as ScienceDirect, PubMed and Scopus MEDLINE were searched. A total of 1212 titles and abstracts were identified; of which only nine papers formed part of this study. The results indicated that there is a dearth of research on the management of occupational noise–induced hearing loss in Africa. The limited research on the management of occupational noise–induced hearing loss focuses on some aspects of the hearing conservation programme pillars and not on all the pillars as suggested by some scholars in the field. Furthermore, these studies had small sample sizes thereby, minimizing their generalization. There is therefore a need for more studies on the management of occupational noise–induced hearing loss in the mining sector, as there is evidence to suggest that occupational noise–induced hearing loss in African countries is still on the rise.
Keywords
Background
The South African Mine Health and Safety Council (MHSC) 1 states its goal as ‘every mine worker returning from work unharmed everyday: Striving for zero harm’. As far as ear and hearing health, this goal, however, has not been realized despite the concerted efforts from the MHSC and the Chamber of Mines in South Africa. The reality is that approximately 73.2% of miners in South Africa are exposed to excessive noise surpassing the legislated occupational exposure limit of 85 dB, despite hearing conservation programmes (HCPs) implemented in the mining sector.2,3 HCPs are multi-component interventions aimed at managing noise-induced hearing loss in a workplace. 4 Well-integrated and comprehensive HCPs are those that encompass all seven pillars namely: periodic noise exposure monitoring, engineering controls, administrative controls, personal hearing protection, audiometric evaluations, employee/management education and training and record keeping. 5 Amedofu and Fuente 6 argue that the success of HCPs depends on the implementation of all the pillars of the conservation programme.
Numerous studies have been conducted to evaluate the effectiveness and efficacy of management of occupational noise–induced hearing loss (ONIHL) within the South African mining industry. These studies have yielded unfavourable findings, which indicate that significant efforts are still required to successfully manage ONIHL.7–9 Published evidence indicates that the prevalence of ONIHL is high in developing countries such as South Africa. Storbeck and Moodley 10 maintain that hearing loss represents a heavier burden in developing countries than in developed regions of the world because of the challenges faced by developing countries when compared with their developed counterparts. Moreover, ONIHL can present a limitation on the kind of employment suitable for a person with a hearing impairment, 11 which may possibly lead to economic burden for developing countries in particular. Establishing the status of ONIHL and its management in developing countries becomes important if strategic planning around this occupational health challenge is to be systematic and successful. It is therefore with this backdrop that this study was conceptualized. This study aimed to explore and document current evidence reflecting trends in the management of ONIHL in the mining industry in Africa.
Methods
Data sources and literature search
To identify studies reporting the management of ONIHL in the mining industry in Africa, a systematic literature review was conducted in line with the Cochrane collaboration guidelines 12 in conjunction with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). 13 The electronic bibliographic databases that were searched included ScienceDirect, PubMed, Scopus MEDLINE, ProQuest and Google scholar. The search terms used (PubMed mesh terms) included ‘occupational noise induced hearing loss’, ‘occupational noise AND hearing loss’, ‘work- related noise’ OR ‘hearing loss’ OR ‘hearing impairment’ OR ‘disability’, ‘noise in the workplace’ AND ‘Africa’ OR ‘African’ OR ‘sub-Saharan Africa’ AND ‘management’ OR ‘managing’ OR manag* ‘addressing’ OR ‘intervention’ AND ‘mining’ ‘min*’.
Inclusion criteria
Articles selected for inclusion in this study were original pieces of scientific work or reports published in peer-reviewed scientific journals. These articles were conducted in the mining sector in Africa between January 1994 and December 2016. The focus was on the management of ONIHL in the mining sector in Africa. All the articles were published in English.
Data extraction and synthesis
First, articles to be selected for inclusion were independently identified by four investigators (N.M., K.K.-S., A.K. and L.N.) using pre-defined abstraction. Disagreements on papers selected for inclusion were resolved through discussion and consensus among all four researchers. Where consensus was not reached, N.M. as the leading author made the final decision. Second, authors provided a narrative synthesis of the findings from the studies that met the inclusion criteria. The synthesis included the study objectives, study design, study setting and management strategy used in the included studies.
Results
Study identification
A sum of 1212 titles and abstracts were identified, from which 1195 were identified from the databases mentioned previously and 17 manual reviews of the reference lists of the identified publications. A total of 798 titles and abstracts were excluded due to duplication. Around 414 abstracts were screened, and 377 were removed post abstract review, as they did not meet the criteria in terms of being conducted in the mining sector in Africa. Consequently, only 37 articles were subjected to a full-text review, of which 28 were excluded as they were not original research articles or peer-reviewed. Eventually, a total number of nine studies were eligible for inclusion in the study. Of the nine articles reviewed, two focussed on the use of engineering controls; one on administrative controls; four on the use of personal protective devices, and one on education and training as a means of eliminating ONIHL in the African mines. Figure 1 presents the PRISMA flow diagram describing the process of study selection. The findings of each selected study were reviewed and synthesized qualitatively, as there was substantial heterogeneity among the studies reviewed.
The PRISMA flow diagram describing the process of study selection.
Studies characteristics
Study designs
Four studies used cross-sectional descriptive research designs where structured questionnaires and face-to-face interviews, and observations were used to collect data. One study used a retrospective record review of audiograms to analyse the efficacy of an HCP; while another study used multiple measures personal qualitative observations, empirical theory evidence and quantitative descriptions. One study used a web-based survey design; another used functional analysis; while another used workshops utilizing obstacle-based planning techniques (Table 1).
Describes details of study characteristics of each included study.
HCP: hearing conservation programme; HPD: hearing protection device; NIHL: noise-induced hearing loss; ISO: International Organization for Standardization; BQI: buying quiet initiative.
Study settings
Of the nine studies included, seven were conducted in mining contexts in South Africa, while of the remaining two; one was conducted in Ghana and the other in Zimbabwe.
HCP pillar targeted as a means to manage ONIHL in the mines
The reviewed studies focussed on four of the seven documented pillars of successful HCPs. These pillars included engineering controls, administrative controls, personal protection devices, as well as education and training. Current findings on these four pillars are presented in this order below.
1. Engineering controls
Two studies focussed on the use of engineering controls as a means to reducing noise at its source in the mining industry. First, in a study by Gumede et al 14 development of a proposed strategy and structure for the buying quiet initiative (BQI) was investigated. This initiative focussed on adopting and promoting the use of quieter machines as a strategy of controlling noise at its source. Findings of this study highlighted that the mining industry does acknowledge BQI as a proactive strategy that will significantly reduce ONIHL and improve the management of noise at its source. However, this study also identified a number of obstacles in the implementation of BQI. The most serious obstacle concerned the formation of a well-constituted industry-wide task team which should include various representatives from relevant and key industry stakeholders. Furthermore, concerns regarding proper scoping, management leadership and the mining industry’s adherence to the initiative were raised. Moreover, lack of involvement by stakeholders as well as economic constraints were also identified as potential obstacles in the implementation of BQI.
Second, in a study by Burger et al., 21 the focus was on developing a low-noise blast hole drilling system in order to reduce the risk of ONIHL in the mining operations. The rationale for this study highlighted the benefits of using this drill such as removing the operator from the areas of excessive noise and minimizing the need for operators to support the drill, thereby eliminating the risk of vibration-induced injury. Results from this study indicated that the developed low-noise rock drill achieved the noise level specification as stipulated in the legislation, thereby enabling the mining industry to be compliant with the ONIHL regulations.
2. Administrative controls
Of the studies reviewed, only one study focussed on administrative controls. This study was conducted by Steenkamp 19 and aimed to contribute towards best practice according to the ISO with regards to implementing HCPs in the mines. Therefore, this study revisited existing HCPs to report on the trends in order to address the weaknesses of current hearing conservation practices in South African mines. This study presents the six-sigma model, which seems to be a useful model that can serve as a quality management tool of HCPs and assist in managing ONIHL. It advocates for personalized aspects of HCPs such as custom-made hearing protection devices (HPDs). Implementing this model requires that all the pillars of the HCP be subjected to measurement. These measurements should include audiometric testing and monitoring of ONIHL using objective measures as well; worker orientation and education related to HCP; optimal and appropriate custom-made HPDs, as well as consistent use of HPDs by workers.
3. HPDs
Four studies focussed on the use of HPDs as a means of managing ONIHL. While these studies indicated that the use of HPDs is a preferred method; there were challenges associated with the use of HPDs in the mines.
First, Ntlhakana et al 15 conducted a study in the gold and non-ferrous mining subsectors in South Africa and focussed on the use of HPDs in the workplace. A total of 90 mine workers from two mines (Gauteng province: 65 and Limpopo province: 25) were interviewed using a questionnaire with open- and close-ended questions. Direct observations were incorporated in this study where underground miners were observed to verify if they used HPDs when working in noisy places. Findings of this study confirmed the ineffectiveness of the HCP programme as far as the use of HPDs was concerned. All the participants in the study reported using HPDs; however, comfort, design and work-related communication were identified as barriers to poor and inconsistent use of these. Also, the authors specifically reported that participants were aware of the importance of protecting and preserving their hearing; however, this was not motivation enough to use HPDs; therefore, prompting the need for more focussed education on the impact and implications of exposure to hazardous noise levels in the workplace.
Second, in a study conducted by Hansia et al, 20 the actual and reported use of HPDs by participants exposed to excessive noise at a gold mine was explored. Furthermore, this study assessed the workers’ reported knowledge, attitudes and practices relating to ONIHL and HPDs use. This study consisted of 101 participants who were interviewed and observed during their work shifts. The authors reported that some participants (13%) erroneously indicated that their workplaces were not noisy, while 16% did not think that noise was a hazard in the workplace, and 6% were not aware of the importance of using hearing protection when exposed to excessive noise. Around 3% reported that they believed HPDs did not protect hearing. In this particular study, while the majority (n = 93) of the participants reportedly used HPDs, only 50% were observed using their HPDs consistently. A small number (8%) of participants reported that they were not informed about the benefits of using hearing protection despite being informed. The authors reported that the participants claimed that HPDs were uncomfortable; hence their poor adherence to their use. Around 57% preferred other training methods other than the current computer-assisted training. However, the other preferred methods are not listed.
Third, in a study by Steenkamp, 16 the aim was to determine the occupational effects of quality hearing protection in terms of health, safety and productivity. Moreover, this study also documented the testimony and the experiences of using a custom-made hearing protection device (CHPD). Findings in this study revealed that workers used their CHPDs, and this was recorded as a great improvement when compared with standard HPDs use. The results also reinforced that CHPDs are a preferred choice in terms of the workers’ medical and occupational hygiene hearing ability status. Furthermore, CHPDs improved work in terms of quality, safety and productivity. In addition, the workers who were fitted with CHPDs expressed satisfaction with this type of protection.
Finally, the fourth study by Mutara et al 18 aimed to analyse an HCP at a mining company in Zimbabwe. This study consisted of 120 employees who completed individual questionnaires and took part in a focus group discussion. Findings of this study indicated that the company provided HPDs (plugs, noise-ban customized hearing devices and earmuffs) to their employees and that the majority of the employees used the HPDs to protect their hearing. Furthermore, in this study, the company conducted annual audiometric testing for all employees. However, there were setbacks identified as some of the employees did not use their HPDs despite having been educated on the how and the why of using hearing protection. This prompted the authors to recommend that the company should enlist the services of a resident audiologist to assist non-compliant employees.
4. Education and training
Edwards et al 8 conducted a descriptive survey to evaluate ONIHL awareness training programmes in six mines in South Africa. Findings of this study, first, indicated that there was lack of prioritization of commitment to awareness training, and that this challenge received little priority in all the participating mines. Second, findings revealed that a large majority of the mines (80%) lacked a solid and consolidated theoretical basis for their awareness training programmes. Third, language used during the awareness training seemed to be an influencing factor where there did not appear to be a standard language policy followed. In this study, the awareness training programmes were conducted 30% in English only, 40% in the employees’ language of choice and 30% combined English and Zulu. Finally, findings from this study revealed that 60% of the participating mines did not evaluate employees’ acquired knowledge post training.
5. Audiometry evaluation
Amedofu et al 17 sought to examine the effectiveness of an HCP in a large surface gold mine in Ghana. In this study, a retrospective review and comparison of mine workers’ audiograms from 1993–2003 was conducted. A total of 200 mine workers participated in this study. According to this study, the implementation of HCP was introduced in 1999 at the research site. The results revealed that hearing loss worsened in 5.5% of the participants, while in 1.5%, hearing function improved. The authors concluded that evidence from their study indicated that the HCP implemented in Ghana was effective, as over 90% of the participants did not present with further hearing loss during their study. The conclusion from this study seems to have been solely based on the audiograms obtained from the mining company and data were collected from one large-scale mine with only 200 audiograms having been evaluated. This identified limitation in the methodological design of the study suggests that concluding that HCP was effective based on such a small population may have been premature and a similar study with a larger sample may yield more accurate results.
Discussion
This review study identified nine studies which met the inclusion criteria for the systematic review. The studies that were selected were heterogeneous; therefore, attempts were not made to conduct a quantitative synthesis or meta-analysis.
Although ONIHL is not life threatening, unmanaged hearing loss may have a profound impact on the quality of life of the affected individual 22 as ONIHL is irreversible and untreatable as the hair cells, once damaged, cannot be restored. 5 However, ONIHL is preventable through a systematic and comprehensive effective HCP that includes all eight pillars of HCPs.5,17
During this study’s qualitative synthesis, it was noted that no single study attempted to comprehensively and holistically address all the eight pillars of an HCP in the mines. Current authors believe that the failure of conducting comprehensive and holistic studies may be attributed to the fact that HCPs are complex programmes or complex interventions with multiple and multifaceted component/pillars conducted in complex environments with various sources of noise and various stakeholders. Conducting such comprehensive studies may be time consuming; and may require significant resources and commitment from different stakeholders. Regardless of these challenges, current authors believe that if the South African mining industry is fully committed to the elimination of noise and its impact in the mining industry, such studies will need to be conducted to ensure that interventions yield successful HCPs.
Studies reviewed in this study only focussed on four pillars, in a piecemeal fashion; namely engineering controls; administrative controls; personal hearing protection and education and training. These studies neglected periodic noise exposure, audiometric evaluations and record keeping. Overlooking periodic noise exposure monitoring has implications for the entire programme as this pillar serves to identify individuals exposed to excessive noise in the workplace. 23 According to the Workplace Safety and Health Council, 23 noise monitoring should be conducted every time any alterations are introduced and applied on the machines or every 3 years, if there are no changes introduced in the workplace.
Another pillar that was not featured in any of the studies reviewed was record keeping. To maintain accountability, effective record keeping is crucial and it requires commitment and consistency, as ONIHL develops gradually and overtime; therefore, keeping records of each employee becomes crucial, as records can be used to determine the employee’s exposure to noise. 24 Proper record keeping allows for effective and accurate programme evaluation which is important for programme sustainability if successful; and/or programme changes where challenges are identified. 24 Proper record keeping also allows for accurate and appropriate individual conservation programme implementation where employees’ compounding factors such as concomitant exposure to other toxins (e.g. co-occurrence of TB and HIV with ototoxicity) can be taken into careful consideration in employee HCP plans. Furthermore, proper record keeping allows for accurate comparative analysis of employee thresholds for compensation purposes; should this eventuality come. Proper record keeping also facilitates accurate research to be conducted to allow for relevant evidence base that can be accessed by the mining industry to enhance their HCPs. With regards to the pillars that were targeted in the included studies, majority focussed on the use of personal hearing protection. While some authors have argued that HPDs remain the most used method of prevention of ONIHL despite their limitations; they also emphasize that HPDs are fully effective when used in conjunction within a comprehensive HCP.4,25–29 However, the Department of Minerals and Energy in South Africa 30 strongly recommends that the use of personal protection devices should be regarded as the last resort if engineering and administrative controls and audiometric evaluation measures fail. Current evidence, however, suggests that there is an over-reliance on hearing protection devices in the workplace.5,31–33 This was also evident in this study as the majority of the studies focussed on HPDs. Furthermore, it should be highlighted that there are challenges associated with the use of HPDs such as discomfort, negative impact on work-related communication and the design of the HPDs as was reported by the studies included in this review. Several authors15,31,34 support that these challenges impact on compliance and adherence to using HPDs. These findings have profound implications for industries that do not use HPDs as part of a comprehensive HCP as they imply that workers who find their HPDs uncomfortable, they will expose themselves to hazardous noise in the absence of other effective HCPs measures protecting their ears against noise injuries. Therefore, it is also the view of the current authors that HPDs; although, seemingly they minimize the amount of sound energy to the ear, should be used in conjunction with the engineering and administrative controls – and not as a primary strategy.
It is encouraging that three studies conducted in this review focussed on the use of engineering and administrative controls to combat noise in the mining industry. Conducting such studies is critical as engineering and administrative controls are the first line of defence against exposure to loud noises.24,35 The ideal goal is to reduce the noise levels at the source so that other elements of the HCP are not needed. 24 The benefits of implementing administrative controls and engineering controls include ‘permanence, effectiveness with or without worker/supervision compliance, less absenteeism, easier communication, lower worker compensation costs and reduced legal costs’ 33 ,p.33. For engineering and administrative controls to be effective, management has a responsibility to make sure that noise sources that can be controlled through these controls are identified and prioritized and that the resources are allocated accordingly. 36 The results of this study highlighted the benefits of implementing engineering and administrative controls; however, they also highlighted the obstacles such as lack of commitment from management and poor formation of key task team members. According to Patel et al, 37 the lack of enforcing regulatory requirements in the workplace is the major downfall to the success of engineering controls. In addition, there is a misconception that implementing noise controls is too arduous and costly; hence, the lack of synchronized distribution of information regarding the importance of noise controls in the workplace. 33 Although the argument of noise controls being too costly is legitimate; current authors believe that this cost is a once off monetary cost as opposed to the significant benefits to the health and quality of life of employees in the immediate and long run. The benefit also includes the elimination of compensation costs, which might increase significantly in the future with improved employee awareness of their rights as well as health and safety regulations.
Victor Hugo, a French author and playwright once stated ‘No cause can succeed without first making education its ally’ 38 ,p.6. These sentiments were highlighted by the studies included in this review.8,15,18 Patel et al 37 reported that most of the barriers experienced by the miners can be addressed by simply educating and training them on the importance of preserving their hearing. Stanton 39 rightfully emphasized the importance of educating, not just the miners but the management also on hearing conservation practices. Education and motivation are a priority in minimizing hearing loss in the mines as they create opportunities for both management and employees to discuss and agree on commitments, communication lines and cooperation. 24 Training can be conducted to explain various and pertinent topics such as the effects of noise on hearing, as well as the purpose and value of wearing HPDs. In a training programme, advantages and disadvantages of hearing protectors being offered by the company can be discussed in detail. Also, this may serve as an opportunity for highlighting the miners and operators’ responsibilities in maintaining noise controls, while also describing the purpose and the value of audiometric testing. 24 If individuals understand the reasons and the benefits of an HCP, they are more likely to participate, especially if training addresses the specific needs of individuals exposed to excessive noise. Current authors strongly concur that all the stakeholders and policymakers involved in the management of ONIHL should be trained in the long-term impacts and effects of ONIHL regardless of whether these stakeholders and policymakers are exposed to noise or not. This is especially true for the management and employers who may not be directly exposed to noise as knowing and understanding the impact of noise may guide the stakeholders and policymakers in implementing HCPs that are realistic and relevant.
Although one study focussed on the use of audiometry surveillance as a means of monitoring employee’s exposure, it should be noted that this study was based on archived record reviews. This is not in line with the Occupational Health and Safety (OSHA) standards. According to OSHA, 40 audiometric evaluations are conducted to monitor an employee’s hearing status over a period of time; as they play an important role in the HCP. Audiometric evaluations help identify employees who may be at a risk of developing occupational hearing loss. 23 Audiometric evaluations serve as an early detection process, since the symptoms of hearing loss do not readily manifest until a significant threshold shift occurs. 23 For effective evaluation, audiometric evaluations should be conducted at pre-employment; prior to assignment to a work area that has high volumes of noise; annually, if the employee is still working in a noisy area; when being reassigned to another area after being exposed to noise and finally, at the termination of employment. 40 The two most important audiograms in the HCP are the baseline audiogram and the annual audiograms. 40 Furthermore, audiometric evaluations serve as an opportunity to educate and train employees about the importance of preserving their hearing as employees who understand the objectives of an HCP are more likely to protect their hearing. 40 Employers are mandated to keep audiometric evaluation results for as long as the worker is employed. Therefore, this study highlights the need to conduct ongoing baseline and annual audiograms.
Over and above the aforementioned challenge identified in this review of the fact that no single study focussed on comprehensive HCP (inclusive of all pillars) in the management of ONIHL. There were also shortcoming with the methods used to collect data. Of the studies that utilized interviews and questionnaires and archival record reviews, the highest number of participants included was 200. These small sample sizes negatively impacted the ability of the findings to be generalizable.
Conclusion
Evidence-based interventions founded on best practice are critical in any health and safety programme. The fact that HCPs are complex interventions that include a variety of factors and a range of stakeholders, with diverse influencing factors; current findings are concerning. First, the fact that there is such limited research conducted on HCPs in Africa is a significant drawback to the collation of contextually relevant evidence that can be used to implement effective HCPs; and the fact that most of this evidence was from South Africa alone is an even bigger concern. Second, the piecemeal fashion of studies that have been conducted, where individual pillars instead of comprehensive holistic HCP analysis is done also impacts negatively on identifying gaps and/or weak links in any HCP. Third, the fact that only four of the pillars have been investigated over the review period limits the amount of evidence available to the mines as well as evidence for future planning. Finally, the fact that the studies reviewed generally included small sample sizes means that findings from these studies are not easily generalizable to the African mines generally. Current findings, which provide an overview of studies in HCP and ONIHL in Africa, add to the evidence base which can be consulted in planning future studies, in formulating policies around hearing conservation and in planning and implementation of HCPs. These findings should be interpreted taking careful cognizance of the design and methodology adopted in the review.
Footnotes
Declaration of conflicting interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship and/or publication of this article.
Funding
The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This research was supported by the African Academy of Science under a DELTAS Africa Initiative grant [107768/Z/15/Z] as part of the Consortium for Advanced Research Training in Africa (CARTA).
CARTA is jointly led by the African Population and Health Research Center and the University of the Witwatersrand and funded by the Carnegie Corporation of New York (Grant No–B 8606.R02), Sida (Grant No:54100029), the DELTAS Africa Initiative. The DELTAS Africa Initiative is an independent funding scheme of the African Academy of Sciences (AAS)’s Alliance for Accelerating Excellence in Science in Africa (AESA) and supported by the New Partnership for Africa’s Development Planning and Coordinating Agency (NEPAD Agency) with funding from the Wellcome Trust (UK) (Grant No: 107768/Z/15/Z) and the UK government. The statements made and views expressed are solely the responsibility of the fellow.
The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.