Factors Affecting the Risk of Injury from Manual Materials Handling

Strains and sprains from manual materials handling are significant causes of workplace injury. Although lifting, placing, carrying, holding, and lowering are involved in manual materials handling (the principal cause of compensable work injuries), Bureau of Labor Statistics data shows that four out of five of these injuries were to the lower back, and that three out of four occurred while the employee was lifting an object.

Management and workers should both be involved with analyzing and assessing manual materials handling job tasks for risk of injury. When a manual materials handling task has been assessed as a risk, the first control option should be redesign (i.e., redesigning the task so that the risk is completely eliminated). If this is not possible, the risk should be reduced through the use of mechanical aids and training.

Consider the following factors when assessing the risk of a manual materials handling task:

Weight – A lighter load normally means a lesser risk of injury. The weight of the objects should be within the capacity of the person to safely handle.

Type of Handling – It is easier to pull or push a load, than to lift, put down, or carry it.

Position of the Load – When lifting, there is much less force on the spine if the load is held in front and comfortably close to the body. Twisting and bending during lifting puts more force on the spine and increases the risk of injury, even for light loads.

Frequency – The more times a load is handled, the more tired the muscles become, making it easier for a person to be injured.

Distance – The farther the load has to be moved, the greater the risk of injury.

Duration (time) – Where the job involves repetitive movements, reducing the time spent on handling will help to ensure the movements are not causing unnecessary strain.

Forces Applied – Forces should be applied smoothly, evenly, and close to the body. Forces exerted should be well within the capacity of the person, and the person should maintain proper posture.

Nature of the Load – Loads that are compact, stable, easy to grip, and capable of being held close to the body, are much easier to handle.

Terrain – Rough ground, steep slopes, slippery and uneven floors, stairs, and cluttered floors make moving a load awkward and increase the chance of injury.

Environment (Climate and Lighting) – If it is too hot, too humid, too cold, or the lighting is inadequate, the capacity to work safely is reduced.

Condition of the Workplace – Safe and comfortable working conditions, with adequate space to perform the task, and tools and equipment that are well-maintained, make the job safer.

Age/Gender – Young and old workers alike may be at an increased risk of injury from manual materials handling activities.

Training – Proper training for the specific task is vital to reduce injury.

Team Lifting – If one person cannot lift or move a heavy, large, or awkward object safely, organize a team lift. Team lifting reduces the risk of injury, reduces fatigue, and makes the task much easier.

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