Risk factors for musculoskeletal disorders in manual handling of loads

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Metka Teržan, Institute for Occupational Safety, Slovenia

Introduction

Manual handling operations involve the transporting or supporting of a load, including the lifting, lowering, pushing, pulling, carrying or moving of a load by the hands or through the application of bodily force. There are several risk factors that make manual handling of loads hazardous and increase the risk of injury. Particularly, for back pain, these can be grouped into five main categories: the load; the task; the environment; organisational and psychosocial factors; and individual and lifestyle factors. Risk assessment methods have been developed to provide comprehensive information about the complex interactions of risk factors associated with the handling of loads.

Manual handling occurs in almost all work environments (hospitals, factories, warehouses, building sites, farms, offices, etc.). The Directive 90/269/EEC lays down health and safety requirements for the manual handling of loads [1]. The aim of the directive is to reduce or eliminate the risk of injury associated with manual handling operations in all workplaces, regardless the economic sector.

The prevalence of musculoskeletal disorders associated with manual handling

The manual handling of loads can lead to discomfort, pain or injury to the musculoskeletal system. In particular, back pain is a major work-related health complaint associated with manual handling and occurs across the European Union (EU).

The sectors with the highest number of work-related musculoskeletal disorders (MSD) are: Agriculture; health and social work (N85); transport; storage and communication; and[2].

According to the Sixth European Working Conditions Survey carried out by EU-27 in 2015, 33,0% of all workers are exposed to the risk of carrying or moving heavy loads for at least a quarter of their working time. An analysis of data from an earlier EWCS survey shows the highest exposure rates are found amongst high-skilled manual workers (figure 1) [3].

Figure 1 – Exposure to the risk of carrying or moving heavy loads - EU27 - 2010

Msd 5.jpg

Source [3]

Musculoskeletal disorders have the highest impact on sickness absenteeism of all work-related health problems within the EU. Bone, joint or muscle problems that mainly affect the back occur more often than resp. upper limb and lower limb disorders [4].



Manual handling risk factors and musculoskeletal disorders

Multiple risk factors

There are a number of risk factors that make manual handling of loads hazardous and increase the risk of musculoskeletal injury. Whilst each of these risk factors may independently contribute to the development of musculoskeletal disorders, the risk is greater if several risk factors are present at the same time [5]. Examples of risk factors within the five major risk factor categories are:

The load:

  • heavy, bulky or unwieldy;
  • difficult to grasp;
  • unstable or likely to move unpredictably (like animals);
  • harmful, e.g. sharp, hot;
  • too large for the handler to see over or around.

The task:

  • holding loads away from the body;
  • awkward and static postures, e.g., working with hands above shoulder level, sitting;
  • applying high forces, e.g., lifting, carrying, pulling, pushing and using tools;
  • long carrying distances;
  • repetitive movements, especially if they involve the same joints and muscle groups, and if they involve high force exertions.

The work environment:

Organisational and psychosocial factors:

Individual and lifestyle factors:

  • medical history;
  • physical capabilities;
  • age;
  • obesity: the anthropometric characteristics of obese handlers are linked to a significant increase of peak lumbar loading [6];
  • smoking;
  • acute trauma;
  • pregnancy;
  • lack of work experience, training or familiarity with the job.

Characteristics of the load

The characteristics of the load highly impact the risk of MSDS. Especially if one of the following conditions is present during lifting, carrying, and the pushing and pulling of loads, the risk of back injury increases

Heavy load

There is no single weight limit for manual handling. A weight of 20 to 25 kg is heavy to lift for most people, especially if loads are handled repeatedly. Research shows that lifting heavy loads may have a substantial impact on musculoskeletal health [7]. It should be noted that pushing or pulling causes less strain on the lower back than lifting or carrying.

Large load

One basic recommendation for lifting and carrying is to keep the load as close to the body as possible. In order to grasp a large load, the handler has to adopt a posture with the arms extended, thus increasing the spinal loading.

Difficult to grasp

Loads that are difficult to grasp can result in the object slipping, causing sudden movement of the load. Gloves usually make holding objects more difficult than with bare hands. Providing the objects with handles or using aids to assist gripping (e.g. when carrying metal plates) reduces the load on the handler. Loads with sharp edges or containing dangerous materials (solids or liquids) present a risk to handlers, especially in the event of a collision.

Unbalanced, unstable or if the contents can move

With unbalanced objects, it is difficult to hold the centre of gravity of the load close to the body. This may lead to asymmetrical loading of muscles, and potentially lead to fatigue. Unstable or moving contents, such as liquids, are particular hazardous as the load can suddenly move causing the handler to lose their balance, with the possibility of them falling.

Difficult to reach

Loads that can only be reached with outstretched arms, or by bending or twisting the trunk, often require more muscle force. When lifting, the spine is particular at risk of injury when the trunk is bent or twisted.

While some musculoskeletal disorders are caused by the sudden application of a high force, most often they are the result of many repeated, apparently moderate force applications, sustained over an extended period of time.


Manual handling risk assessment

Given the risks associated with many manual handling tasks, employers are required to assess the risks and ensure the health and safety of their employees. The weight of the object, the hold on the object and the position of its centre of gravity are important issues when assessing the risk of injury from manual handling tasks. A poor work environment, (e.g. the space available to perform handling tasks, temperature, humidity, etc.) can compromise muscle efficiency and may lead to vascular and neurological damage of the musculoskeletal system. Workers with cold hands may exert greater forces than normal, affecting muscles, soft tissues and joints. It is important to be aware that individuals differ in their susceptibility to musculoskeletal injury.

Under the EU Council Directive 90/269/EEC [1], employers are required to avoid the need for manual handling of loads by workers. Where this is not possible employers must assess the risks associated with manual handling in the workplace, and act to safeguard the safety and health of their employees and others who may be at risk. A Risk assessment involves a systematic and thorough evaluation of the hazards in the workplace and the likelihood that these could cause harm to an individual. On the findings of the risk assessment, it can then be decided whether sufficient precautions have been taken to prevent injuries occurring, or whether further action is necessary [5]. The benefits of a good risk assessment are that they can help reduce the costs to businesses from lost output, compensation claims and higher insurance premiums.

The starting point for a risk assessment in small and medium sized enterprises is to observe the work environment and work tasks. The use of a simplified checklist to identify potential hazards can be of great benefit in ensuring that all risk factors are identified. It is important that employees are involved in this process as they are the ‘experts’ when it comes to identify hazards in their workplace. Some examples of suitable risk assessments can be found on national and international health and safety at work websites. For example, the checklist for the prevention of manual handling risks on the EU-OSHA website. The checklist allows assessing the risks related to manual handling and examines risk factors related to:

  • the weight and specific characteristics of the load
  • the task and organisation of work
  • workplace layout and equipment
  • work environment
  • individual capacity, skills and training level.

The checklist also provides examples of preventive measures [8].

Another example is the risk assessment tool developed by HSE (UK): the Manual Handling Assessment Chart (MAC) [9]. This risk assessment tool was developed to provide comprehensive information about the complex interactions of risk factors involved in the handling of loads. Methods like this are practical, efficient and reliable. They can be applied equally by all potential users: labour inspectors, employers, workers, safety engineers, occupational physicians, etc.

This and other similar methods are based on a linear interpolation, mathematical model. The risk factors which must be taken into account when carrying out an assessment of the risks are primarily: loads characteristics, the physical stress exerted on the handler (distance of the load, adopted posture, intensity of the task, frequency and duration of the required handling task, etc.), characteristics of work environment, age, gender, and working experience.

Once data has been collected there are some computer programmes that can be used to calculate the risk of injury to the handler. In many cases, some of these methods have been incorporated (as employer decision support tools) into company specific guidelines. The output from these risk assessment guidelines is not a ‘safe limit’ for lifting, but guidelines for preventing injuries.


The prevention of manual handling related injuries

One approach to the prevention of work-related musculoskeletal disorders is through health and safety guidelines and directives. For example, Directive 90/269/EEC specifies health and safety requirements for the manual handling of loads. Each Member State has transposed these requirements into national law [10]. However, the Directive is of a general nature, so as to allow implementation in different ways by each Member Country.

Under EU legislation, each employer must undertake a suitable and sufficient risk assessment of those manual handling operations that pose a risk to an individual and take appropriate steps to prevent the risk of injury. Whilst training programmes are of crucial importance to injury prevention, they are not on their own, a suitable substitute for a lack of mechanical aids, inappropriate loads and poor working conditions. There are several health care prevention strategies that target first occurrence of a condition (referred to as primary prevention, and includes the preventing the recurrence of symptoms after the first occurrence), secondary prevention and tertiary prevention. The latter includes the reduction of the progression of a condition and is more related to treatment, rehabilitation and reintegration of workers who already suffer from musculoskeletal conditions.

Many MSDs from manual handling can be prevented, or greatly reduced by complying with existing health and safety regulations and following guidance on good practice. However, effective prevention measures are considered to include: designing and organising tasks to avoid manual handling, or at least to reduce it; the use of automation and lifting aids, organising manual handling tasks in a safer way (e.g. dividing the load into smaller items, and ensuring appropriate rest breaks), and providing information and training to workers about the tasks, the use of equipment and correct handling techniques.

There is a growing body of practical guidance and examples from workplaces about how to prevent manual handling risks. National health and safety authorities and EU-OSHA [11] are among those who provide such information. Nevertheless, every workplace is different, which means employers must carry out an assessment of the risks at their own workplace so that those solutions that are developed are specific to their own situation.


Conclusion

Musculoskeletal disorders are one of the most common causes of occupational ill-health in the EU, thereby representing a major public health issue. Prevention has mostly been targeted at providing resources to address a number of key areas, mainly through improving compliance with the regulations. Nevertheless, further improvements must inevitably involve changes to cultural practices making musculoskeletal disorders a public health priority.

The good news is that good practices in many enterprises throughout the EU have show that musculoskeletal disorders are preventable if employers and employees follow existing health and safety regulation, guidance and their own experience for improving and making their work safer.


References

  1. 1.0 1.1 Directive 90/269/EEC – manual handling of loads, of 29 May 1990 on the minimum health and safety requirements for the manual handling of loads where there is a risk particularly of back injury to workers (fourth individual Directive within the meaning of Article 16 (1) of Directive 89/391/EEC). Available at: [1]
  2. EUROFOUND – European Foundation for the Improvement of Living and Working Conditions, Musculoskeletal disorders and organisational change, 2007. Available at: [2]
  3. 3.0 3.1 EUROFOUND – European Foundation for the Improvement of Living and Working Conditions, Fifth European Working Conditions survey - 2010, Survey mapping tool. Retrieved 2 March 2015 from: [3]
  4. EUROSTAT - Health and safety at work in Europe (1999-2007) - A statistical portrait, Inna Šteinbuka, Anne Clemenceau, Bart De Norre, August 2010. Available at: [4]
  5. 5.0 5.1 SLIC – European inspection and communication campaign, Thematic Day, Supervising Council Directive 90/269/EEC, Committee of Senior Labour Inspectors, European Commission, Maastricht, Netherlands, November 4, 2004.
  6. Corbeil, P., Plamondon, A., Teasdale, N., Handrigan, G., Ten Have, J., Manzerolle, N., Biomechanical and Ergonomic Impacts of Handling in Obese Workers, Report R-825, IRSST, 2014, Available at: [5]
  7. Coenen, P., Gouttebarge, V., van der Burght, A., van Dieën, J., Frings-Dresen, M., van der Beek, A., Burdorf, A., 'The effect of lifting during work on low back pain: a health impact assessment based on a meta-analysis', Occupational & Environmental Medicine, 2014, 71, pp. 871-877
  8. EU-OSHA - European Agency for Safety and Health at Work, E-fact 44 - Checklist for the prevention of manual handling risks, Available at: [6]
  9. HSE – Health and Safety Executive, Manual handling assessment chart (MAC) tool, 2014. Available at: [7]
  10. EU-OSHA – European Agency for Safety and Health at Work, Directive 90/269/EEC - manual handling of loads. Retrieved 10 June 2015 from: [8]
  11. EU-OSHA – European Agency for Safety and Health at Work, Report - Prevention of work-related musculoskeletal disorders in practice, Office for Official Publications of the European Communities, Luxembourg, 2008. Available at: [9]


Links for further readings

EU-OSHA – European Agency for Safety and Health at work, Work related musculoskeletal disorders (MSDs): an introduction, E-fact 9, 22.1.2007. Available at: [10]

EU-OSHA – European Agency for Safety and Health at Work, Hazards and risks associated with manual handling of loads in the workplace, Factsheet 73, EU-OSHA, Belgium, 2007. Available at: [11]

EU-OSHA – European Agency for Safety and Health at work, Work-related musculoskeletal disorders: prevention report, 2008, Available at: [12]

EU-OSHA – European Agency for Safety and Health at work, Hazards and risks associated with manual handling in the workplace, E-fact 14, 2007, Available at: [13]

EU-OSHA – European Agency for Safety and Health at work, Work-related Low Back Disorders, 2000, Available at: [14]


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