There are several risk factors that make the manual handling of loads hazardous and thereby increase the possibility of injury. Especially for back injury, they are related to different aspects of manual handling of loads:
too heavy: there is no exact weight limit that is safe;
unbalanced or unstable: the centre of gravity of the object being away from the middle of the worker’s body; difficult to reach;
difficult to grasp: loads with sharp edges or with dangerous materials can injure workers;
too large: if the load is large, it is not possible to follow the basic rules for lifting and carrying;
shape or size that obscures the worker’s view.
The manufacturing cycle can increase the risk of injury of the employee in the manual handling of loads:
if it is too strenuous, carried out too frequently or for a long time;