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). Manual handling can also lead to occupational accidents. Around 9% of all non-fatal accidents in the EU-28 can be attributed to Carrying by hand (data from 2017)[2].

According to the Sixth European Working Conditions Survey (EWCS) carried out 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. In the Construction and Transport sector more than half of the working population are exposed to this risk. In sectors with more clerical work such as the Financial sector and Public administration, this percentage is much lower (20% or less) (Figure 1) [3].

Findings from the ESENER survey indicate that Lifting or moving people or heavy loads is among the four most identified risk factors by European workplaces. More than 50% of the workplaces have identified this risk factor and this percentage has increased compared to 2014 [4]. The risk of carrying or moving loads can be associated with all types of MSDs. Based on data from EWCS 2015 an EU-OSHA report (2019) [5] demonstrated that workers who are exposed to the risk of carrying or moving loads, also report more MSDs. Of all the workers whose job always involves carrying or moving heavy loads, around 63 % report having MSDs as opposed to 34% when their job never involves carrying or moving heavy loads. It should be noted that the EWCS include data of self-reported MSDs, not only work-related MSDs. The association between MSDs prevalence and exposure to the risk of carrying or moving heavy loads has been found for upper limb disorders, lower limb disorders and back pain. The more workers are exposed (for a longer period/percentage of their working time) the more likely they are to report an MSD complaint. Figure 2 shows the percentage of workers having backache, by proportion of working time involving carrying or moving heavy loads by age.

Figure 1 – Percentage of workers exposed to the risk of carrying or moving heavy loads by sector, EU-28, 2015

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Source: Eurofound, EWCS 2015 [3]


Figure 2 - Percentage of workers having backache, by proportion of working time involving carrying or moving heavy loads, by age, EU-28, 2015

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Source: Panteia based on the European Working Conditions Survey (EWCS) [5]

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 [6]. 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 [7];
  • 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. However, weight limits can be found in guidance documents and standards. A well-known and widely used reference is the NIOSH recommended weight limit of 23 kg for men and under ideal circumstances used in the NIOSH Lifting Equation [8]. ISO-standard 11228-1 Ergonomics - Manual handling - Part 1: Lifting and carrying proposes a similar limit of 25 kg for men and 15kg for women under ideal conditions. Ideal conditions include aspects such as lifting with 2 hands, trunk is not rotated, lifting duration of less than one hour per day, etc. Lifting under non-ideal conditions decreases the safe lifting limit. Another well-known example are the guidance values of HSE (UK). These values can be used for assessing the risk of manual handling and differ according to the horizontal and vertical reach distance (figure 3). The optimal zone is at elbow height, close to the body. Above shoulder height or below knee height only light weight is allowed [9]. Some EU member states have also included weight limits into their legislation. Directive 90/269/EEC lays down the minimum health and safety requirements for the manual handling of loads. This directive has been transposed into the national legislation of all member states and some of them have included numerical limits for weights lifted (usually 30 kg for men) into their national legislation [10].

Figure 3 – Guidance values – assessing the risk of the weight of a load (HSE)

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Source: [9]

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 [6]. 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 [11]. Other examples of risk assessment tools for manual handling are:

  • the Manual Handling Assessment Chart (MAC) developed by HSE (UK)[12];
  • the Key Indicator Methods (KIM) developed by the German Federal Institute for occupational safety and health (BAUA) and available in German, English, Spanish, French, Dutch and Swedish[13].

These tools make use of observational methods and are practical, efficient and reliable. They are user-friendly and can be applied by ergonomists, occupational hygienists, occupational physicians as well as by employers, labour inspectors, 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

Directive 90/269/EEC imposes that employers should take measures to avoid hazardous manual handling operations. Such measures include redesigning the task to avoid moving the load and/or automating or mechanising the process. If manual handling can not be avoided, the risks should be limited by measures such as:

  • Providing mechanical aids, e.g. conveyors, a pallet truck floor, carts, balancing mechanisms, vacuum hoists, turntables, tilt tables, hooks, automatic pushers, wheels, etc.;
  • Making changes in the work methods such as changing from lifting to pushing or from pushing to rolling, introducing team lifting;
  • Modifying the load, e. g. divide into smaller units, change the shape, provide handles, etc.;
  • Modifying the workplace to reduce carrying distances, twisting movements, or the need to lift things from floor level or above shoulder height;
  • Reducing the total weight handled each day by introducing job rotation;
  • Adapt the work organisation to avoid tight deadlines, provide sufficient storage areas, good work planning, provide sufficient breaks, etc.

Training programmes can help in workers on safe lifting techniques. These training programmes have to be tailor-made, take into account the risks of the tasks and provide practical solutions and techniques. The introduction of exoskeletons can improve the performance of the worker and offer support for frequent lifting of heavy loads. However, the use of exoskeletons remains limited and technical or organisational measures should be preferred over introducing exoskeletons. The use of exoskeletons might create new risks (such as collisions with vehicles or other obstacles), limit the comfort and freedom of movement for the user of shift the physical load to other regions of the body (e.g. to the upper limbs)[14].


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 [15] 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. Eurostat, Causes of accidents at work by physical activity, ESAW, phase III, (hsw_ph3_04). Available at [2]
  3. 3.0 3.1 Eurofound, Sixth European Working Conditions Survey, 2015, Data visualisation tool, Available at: [3]
  4. EU-OSHA, ESENER 2019 Policy brief, 2020. Available at: [4]
  5. 5.0 5.1 EU-OSHA – European Agency for Safety and Health at Work, Work-related musculoskeletal disorders: prevalence, costs and demographics in the EU, 2019. Available at: [5]
  6. 6.0 6.1 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.
  7. 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: [6]
  8. NIOSH, NIOSH Lifting Equation, Available at: [7]
  9. 9.0 9.1 HSE - Health and Safety Executive, Manual handling at work. A brief guide, Available at: [8]
  10. EU, DG Employment, Social Affairs and Inclusion, Evaluation of the Practical Implementation of the EU Occupational Safety and Health (OSH) Directives in EU Member States. Report by directive, Directive 90/269/EC on the minimum health and safety requirements for the manual handling of loads where there is a risk particularly of back injury to worker, 2017. Available at: [9]
  11. EU-OSHA - European Agency for Safety and Health at Work, E-fact 44 - Checklist for the prevention of manual handling risks, Available at: [10]
  12. HSE – Health and Safety Executive, Manual handling assessment chart (MAC) tool, 2014. Available at: [11]
  13. BAUA, KIM method. Available at: [12]
  14. EU-OSHA - European Agency for Safety and Health at Work,The impact of using exoskeletons on occupational safety and health, 2019. Available at: [13]
  15. EU-OSHA - European Agency for Safety and Health at Work, Practical tools and guidance on musculoskeletal disorders, Available at: [14]


Links for further reading

EU-OSHA - European Agency for Safety and Health at Work, Practical tools and guidance on musculoskeletal disorders, Available at: [15]

EU-OSHA - European Agency for Safety and Health at Work, Healthy workers, thriving companies - a practical guide to wellbeing at work, Available at: [16]

EU-OSHA - European Agency for Safety and Health at Work, Conversation starters for workplace discussions about musculoskeletal disorders, Available at: [17]

EU-OSHA – European Agency for Safety and Health at Work, Work-related musculoskeletal disorders: prevalence, costs and demographics in the EU, 2019. Available at: [18]

EU-OSHA - European Agency for Safety and Health at Work, E-fact 44 - Checklist for the prevention of manual handling risks, Available at: [19]

EU-OSHA - European Agency for Safety and Health at Work,The impact of using exoskeletons on occupational safety and health, 2019. Available at: [20]

EU-OSHA – European Agency for Safety and Health at Work, Hazards and risks associated with manual handling of loads in the workplace, Factsheet 73, 2007. Available at: [21]

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: [22]

EU-OSHA – European Agency for Safety and Health at work, Work-related Low Back Disorders, 2000, Available at: [23]


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