Industrial Ergonomics: Material Handling and Back Injury
Industrial ergonomic specialists strive to help employers provide a safe and productive environment for their employees. Ergonomists analyze information about people, tasks, equipment, and workspace in industrial settings found in manufacturing, engineering, and construction. Although industries differ, some tasks may be similar to work performed elsewhere. Lifting and material handling are such tasks that are common to many types of industries such as automobile manufacturing or bridge building.
Industrial Jobs can be Demanding Physically
Jobs in an industrial environment are usually physically demanding and require workers to lift, push, pull, and handle heavy loads. Some individual tasks are repetitious and require the worker to stand or sit for extended time periods. Many industrial work environments involve lifting and material handling. Common causes of back and neck injury related to these tasks include lifting a heavy object from above the shoulders or below the knees, twisting the body while lifting, carrying an object to one side of the body, and bending over at the waist.
Statistical Evidence of Work-Related Back Disorders
Industrial work-related musculoskeletal disorders (WMSDs) are a primary cause of lost work days, productivity, and revenue. According to the Bureau of Labor Statistics (U.S. Department of Labor), during 2002 operators, fabricators, and laborers accounted for almost 4 out of every 10 injuries and illnesses. Additional statistics for this period include:
• Sprains and strains accounted for almost 620,000 cases or 43% of all nonfatal occupational injuries and illnesses.
• The back was involved in 24% of all occupational injuries and illnesses.
• On average, workers with a back or neck injury lost 7 days of work.
• Sprains, strains, and tears accounted for over three-fourths of the musculoskeletal disorders that resulted in days away from work.
In a study published in 2000 by the National Institute of Occupational Safety and Health (NIOSH) for the year 1997, most of the back, spine, and spinal cord disorders were experienced by operators, fabricators, and laborers (41%) and service personnel (19%). During 1997, approximately 799,000 cases of sprains, strains and tears were reported. Nearly half of those cases, about 385,000 involved the back.
Adopt a View toward Injury Prevention
Material handling often involves lifting, carrying, and lowering objects. The National Institute of Occupational Safety and Health (NIOSH) provided guidelines to educate workers how these tasks can be performed using ergonomic principles to help reduce the risk for injury. The NIOSH suggestions are included.
1. Reduce or eliminate the need to manually lift, carry, or lower materials. Some materials can be palletized for bulk handling in large bins or containers and moved by mechanical means.
2. Reduce the weight of the object by reducing the container's capacity or load.
3. Instead of lifting, carrying and lowering objects, convert the job to a push or pull movement. Pushing is the preferred movement. Consider using conveyors, ball caster tables, hand trucks and four-wheel carts. Further, to avoid push/pull movements, convert the movement to powered conveyors, trucks, lift tables, and slides or chutes.
4. Instead of lifting and lowering objects, slide objects.
5. Try to avoid re-handling objects.
When manual lifting, carrying, and lowering are necessary, consider these suggestions:
Step 1: Assess the Situation:
• Assess the load and the situation by testing the weight by lifting one corner. If the object is too heavy, over-sized, or an awkward shape ask for a co-worker's help. If help is not available, consider using a mechanical lift or a hand truck.
• Consider the following before lifting:
When lifted, will the object obstruct your view?
How far will you have to carry the object?
Is the destination pathway clear?
Is the pathway floor flat, slanted, cracked, uneven?
Will curbs, stairs or doorways be encountered?
Is there adequate height and width clearance in aisles?
Does an area need to be cleared to receive the object?
• Wear gloves to help grip the object and protect your hands.
Step 2: Lift, Carry, and Lower with Care
• Position yourself on center and close to the object.
• Stand with your feet shoulder-width apart. Keep feet flat on the floor.
• Tighten your stomach muscles to help support the back.
• Grip the object and hold it close to your body.
• Bend your knees, keep the back straight, and lift using leg strength. The muscles in the legs are stronger and more powerful than your back muscles.
• While lifting, do not twist the body. Lift straight up smoothly - do not jerk the load.
• Look straight ahead, hold the load close, and walk toward your destination.
• Instead of twisting to change direction, turn the feet (e.g. pivot).
• Know where you plan to set the object down. Have a plan in mind.
• To lower and set the object down: keep the load close to your body, bend your knees, and let your leg muscles do the work to lower the object. Remember to keep your back straight and do not twist.
Material Handling Equipment
Many different types of equipment are available to help workers minimize the physical demands of material handling. Chain and lift hoists, conveyors, lift trucks, scissors lift tables, service carts, dock levelers, manipulators and balancers, and stackers are a few examples.
To be effective, these devices are designed for a specific industry application and operators must be instructed in proper use. Proper use should include worker awareness of the ergonomic principles involved to safeguard against musculoskeletal injury.