Preventing and Controlling Back Injuries

Low back pain and injuries attributed to manual lifting activities continue as one of the leading occupational health and safety issues facing preventive medicine. Although no approach has been found to totally eliminate back injuries caused by lifting, an effective training program and ergonomically designed work tasks and equipment will help to prevent a substantial number of this type of injury.

Implementing administrative and work practice controls involves carefully selecting and training workers so they know how to safely perform lifting tasks. Engineering controls are used to redesign a job or use mechanical lifting equipment so the lift becomes less hazardous.

Suggested administrative and work practice controls include:

• Strength testing of existing workers, which has been shown to prevent up to one-third of work-related injuries by discouraging the assignment of workers to jobs that exceed their strength capabilities.

• Training employees to utilize lifting techniques that place minimum stress on the lower back.

• Physical conditioning or stretching programs to reduce the risk of muscle strain.

• Use of two-person lift teams when mechanical lifts are not available.

• Observing micro-breaks to minimize muscle fatigue.

Suggested engineering controls include:

• A reduction in the size or weight of the object lifted.

• Adjusting the height of a pallet or shelf. Lifting which occurs below knee height or above shoulder height is more strenuous than lifting between these limits. Obstructions which prevent an employee's body contact with the object being lifted also generally increase the risk of injury.

• Installation of mechanical aids such as pneumatic lifts, conveyors, and automated materials handling equipment.

Other lift factors to be considered to help reduce the risk of injury include frequency of lifting, duration of lifting activities, and type of lifting, as well as individual variables such as age, sex, body size, state of health, and general physical fitness.

The National Institute for Occupational Safety and Health (NIOSH) has issued a revised formula for the design and evaluation of manual lifting tasks. This updated equation provides methods for evaluating asymmetrical lifting tasks and lifts of objects with less than optimal connection between the object and the worker's hands. It also provides guidelines for a larger range of work durations and lifting frequencies than the previous formula. It is not, however, designed to be applied to situations such as one-handed lifting, lifting extremely hot or cold objects, or to factors that may increase the risk of a slip or fall.

By evaluating on-the-job lifting tasks and using the NIOSH formula to reduce the physical stresses associated with each task, the incidence of low back injuries to workers can be reduced.