LIFTING, PUSHING, PULLING AND LOWERING (Fall 97 issue)

Each year, more American workers suffer back injuries than any other single type of injury. A 1990 report by the National Safety Council indicated that overexertion accounted for 31% of all occupational injuries, and 22% of all injuries were to the back. Most of these injuries are the result of manually handling materials.

In the maritime industry, crew members perform the same tasks as the shore side workers. The only difference is that at times, the platform on which they are standing moves, occasionally quite significantly. Back injuries occur handling lines aboard tugs where the crew has been reduced by the operator to cut costs, moving fish products most often in 50 pound boxes aboard fish processing vessels, manually handling a stretcher carrying another crew member during drills with only two people, or hauling aboard empty barrels from the dock with a line.

The National Institute for Occupational Safety and Health (NIOSH) recognized that steps were necessary to reduce back injuries. Earlier attempts to deal with this problem focused on adopting arbitrary weight limits for lifting loads, or training personnel in the correct method of lifting. Neither approach had much effect on the number of injuries occurring.

In the late 1970's, the NIOSH commissioned a group of experts in the fields of psychophysics, epidemiology, biomechanics, and physiology to review all literature and studies on overexertion and develop a guideline by which lifting tasks could be objectively evaluated.

As a result of their work, NIOSH published Work Practices Guide for Manual Lifting in 1981. This guide provided a formula by which the risk to a worker could be determined for a specific lifting task. The values inputted into the formula were the location of the hands when the lift commenced, the distance the object was lifted and the repetition rate at which the task was performed. The National Safety Council, the largest and most prestigious nonprofit organization dedicated to safety, adopted and republished the guide, providing a slide rule device to do the calculations as well as a computer program into which the same parameters could be entered.

The output was two weights, the first named the Action Limit and the second, the Maximum Permissible Limit. The Action Limit was considered the weight up to which 75% of women and 99% of men could safely lift. The Maximum Permissible Limit was the weight for the particular task above which any person would be exposed to a significant risk of musculoskeletal injury. These tasks required engineering controls, in other words, mechanical assistance or redesign of the task. Weights falling in between the lower Action Limit and the Maximum Permissible Limit required administrative controls. These controls fell into two categories, physical evaluation and training.

The guidelines were accepted by OSHA and applied by them in doing their ergonomics evaluations of lifting jobs in U. S. Industries. It thus became an industry standard. However, there were severe limitations to the type of lifting task that could be evaluated. Foremost was the limitation that the lift being evaluated had to be a two handed lift which occurred in the sagittal plane, in other words, no twisting of the body or carrying of the material.

In the marine industry, larger companies, recognizing that the mariner was not qualified to properly evaluate lifting tasks, had consultants ride their vessels and evaluate lifting tasks that they observed. Exxon was among the leaders and had an extension study conducted using the 1981 NIOSH standard.

The limitations of the 1981 standard caused NIOSH to revisit the lifting task evaluation. In 1994, a revised lifting equation was published in the Applications Manual for the Revised NIOSH Lifting Equation. The new equation evaluated tasks that included twisting up to 135 degrees, the quality of the control that the worker had of the material which he was lifting, and the duration of the repetitive lifting task as well as the frequency. The National Safety Council once again accepted the manual and created a calculator that could be used in the field to make the evaluation.

Another group entered the ergonomics field. They were a group of academians associated with the University of Utah's Department of Mechanical Engineering. Initially, they were funded by the American automobile industry and developed an extensive compilation of ergonomics knowledge and computerized models used in proactive design environments. Foreseeing the potential in the Internet World Wide Web, the group began developing an extensive Web-based system, which soon became known to a world wide audience as "ErgoWeb: the place for ergonomics." Their site has available to subscribers a Tool Box which not only contains computer models for evaluating lifting and lowering tasks, but pushing, pulling, and upper extremity injuries. Further, it provides the online user with suggestions on how to decrease the risks involved in many ergonomic tasks.

Companies have a duty to their employees, ie. ship crew members, aviation baggage handlers, service technicians and ticket clerks who handle baggage, to evaluate their tasks to assure that the workers are not at risk of injury in performing the lifting tasks assigned them. It is of little satisfaction to an injured worker to hear a supervisor say the task has been performed for years and thus is obviously safe.

Where a company has not made a reasonable effort to assure that the employees have a safe working place, they may experience loss of time, workman's compensation claims, or in the case of seamen, Jones Act negligence or unseaworthiness claims.

Captain Greiner of Maritime & Aviation Consultants has done computerized evaluations of lifting tasks under the 1981 standards for years and last year subscribed to ErgoWeb online services described above for evaluation of lifting tasks under the 1994 NIOSH standards and pushing and pulling tasks as well. Other computerized models are available to run comparison evaluations.

The 1994 NIOSH manual containing the lifting equation is available from NTIS for $12 plus handling. Purchases may be made by calling (703) 487-4650. ErgoWeb's Internet address is www.ergoweb.com.

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