Globally, the operation of earth-moving equipment in the mining industry often contributes to prolonged and high magnitude vibration exposure. Load-Haul-Dump (LHD) trucks are used extensively in mining, and the operation of these trucks is characterised by repetitive tasks such as driving while exposed to whole body vibration (WBV). Exposure to WBV and the postural requirements of the job have been identified as important risk factors in the development of musculoskeletal disorders of the spine among workers (Farioli et al, 2014). Changes in mining work practices and a demand for increased productivity has seen almost all heavy physical work in mining replaced with sedentary work and mechanised equipment operation (Bovenzi et al., 2015), the latter resulting in increased exposure to WBV. Operators of LHD trucks, in particular may be at increased risk of injury due to postural demands and whole-body vibrations exposure levels associated with harmful effects to the human body such as LBP (Hinz et al., 2008).
Bellmann (2005) asserts that, lower back pain is one of the leading causes of occupational injury and disability among LHD truck operators. According to Eger et al (2006), lower back pain is a common complaint of LHD truck operators and individuals exposed to occupational whole-body vibration increase their risk of experiencing this discomfort. Lower back pain is a condition of multifactorial origin and several individual, social, and work-related risk factors have been found to be associated with the occurrence of this symptom, for instance age, gender, anthropometric characteristics, previous back traumas, educational level, physical work load, whole body vibrations, psychosocial and psychological risk factors (Seidel, 2005). Eger et al (2008), observed that ergonomic risk factors such as vibration, awkward postures, contact stress, force (forceful exertions), repetition and static postures especially when occurring at high levels or in combination, are most often associated with the occurrence of Musculoskeletal disorders (MSDs). Ergonomic risk factors are the aspects of a job or task that impose a biomechanical stress on the worker (Bovenzi et al., 2015). Bellmann (2005) suggests that LHD drivers are exposed to multiple factors which are considered risks for lower back disorders. These factors include whole body vibration, constrained postures and repeated twisting or bending of the back and neck.
Whole body vibration has been recognised as a main risk factor for low back pain in coal mining activities. Heavy equipment operators in gold mining may be exposed to a higher LBP risk due to the land condition of the overburden overlying gold deposits, which is less stable than that of coal deposits (Godwin, Salmon & Dunn, 2008). Occupational exposure to WBV particularly for heavy equipment operators has increased over the past twenty to thirty years and a positive relationship between long term exposure to vibration and definite medical problems such as degeneration of intervertebral disc, and disc herniation have been shown (Godwin & Eger, 2009). Farioli et al. (2014), identified that occupational exposure to whole body vibration instigating from operation of LHD drivers has been accredited as a significant risk factor for lower back disorders in the mining sector.
Freda Rebecca Gold Mine (FRGM) Limited, formerly known as Ashanti Goldfields Zimbabwe Limited is based in Bindura, Zimbabwe. As of April 30 2005, the mine became a subsidiary of Mwana Africa PLC. It has proven reserves of 2.4 million tonnes of gold as of March 2010 estimates. The company is one of the major employers in the province with an employee compliment of more than 1000 both seasonal and permanent employees. For the past half-decade, the organisation has been implementing various forms of health and safety measures in a bid to reduce occupational health problems and to enhance productivity. However, the use of LHD vehicles at the organisation is prevalent with an estimated 45 operators and as many as 56 dump trucks. As LHD trucks are used extensively in mining at FRGM, the operators of these trucks are exposed to various risks and hazards inherent to this occupation. Heavy mining trucks operators are exposed to a number of factors which are considered risks for lower back pain. This study seeks to explore the ergonomic risk factors causing occupational lower back pain among load-haul-dump truck operators at FRGM, Bindura, Zimbabwe. This chapter discusses the background of the study, statement of the problem and the purpose of the study. It also covers the justification and objectives of the study.
1.2 Statement of the problem
FRGM has experienced an unprecedented escalation of reports of spinal degeneration, spinal disc disease, disc failure, sciatic pain, herniated discs and lower back pain, amongst its underground mine workers particularly in earth-moving equipment operators for the past five years (Freda Rebecca Gold Mine Safety Health Annual Report 2017). There is limited information at the mine about the definite source of lower back pain. Since the mine reopened in 2009 there has been inadequate evidence and studies on ergonomic risk factors and prevalence of occupational lower back pain and its associated occupational factors among LHD truck operators.
The company has a zero-harm safety policy for its employees and all LHD trucks are delivered certified for driver safety. It is agreed that the human body absorbs most vibration frequencies transmitted through the dump truck operator-seat interface. It is said however whole-body vibration frequencies between 1 Hertz and 20 Hertz may cause resonance of the spinal column, pelvis, internal organs and soft tissues (Mansfield, 2005).
It is against these statements of facts that the study explores the ergonomic risk factors that are causing occupational lower back pain among load haul dump truck operators at FRGM. Further the study seeks to look at possible interventions which may require changes in systems, policy, equipment, and driver behaviour, environmental and ergonomic factors.
1.3 Justification of the study
For FRGM this study will be of great value in that the organisation may be encouraged to research more on the issue and then develop a policy to manage lower back pain. This will also assist other industries that are currently faced with the same problem of lower back pain incidents who may benchmark with the findings of this study to address the problems attributed to the incidents which they are facing.
In the sub region of Southern Africa, the results of this study will be of great value in the creation of awareness and lobbying for the comprehensive management of lower back pain. The study results will perhaps augment information to already existing limited data about incidences of lower back pain due to ergonomic factors among LHD operators especially in the Southern African region. The WHO (2002) observes that back pain information is more readily available in developed nations, while LBP data from developing nations is rather limited or scare.
At the international level this study will be of great benefit by adding information which can be used in law and policy formulation and implementation in the management of ergonomic factors which are associated with lower back pain and an overview on the adjustments needed to international laws and polies in respect to lower back pain management. To academia, this study accords an opportunity to students to use these findings of this study to widen their knowledge base in getting a clear understanding of the relationship between ergonomic risks and occupational lower back pain.
1.4.1 General Objective
To analyse the ergonomic associated factors and the prevalence of occupational lower back pain among load-haul-dump truck operators at FRGM.
1.4.2 Specific Objectives
1. To establish the negative health outcomes caused by exposure to whole body vibration among LHD truck operators at FRGM.
2. To assess the association of lower back pain with the operation of LHD trucks at FRGM.
3. To determine the nexus between behavioural factors of individual LHD truck operators and experience of occupational lower back pain.
4. To assess the effectiveness of the risk management and control measures that are available in managing whole body vibration exposure at FRGM.