New back belt study may not tell the whole story
To the editor: I am concerned about the article in the February 1997 issue of Occupational Health Management titled "About face: Major study now says back belts do work, and work well." The article refers to a study of 36,000 Home Depot workers over a six-year period. The article states that the researchers "found that the number of low-back injuries fell by about one-third after the company imposed a consistent policy on belt use." I don’t believe the article or the study tells the whole story about the most likely cause for the reduction in injuries.
Prior to this study, the only two processes that have been found to reduce the incidence of low-back injuries are lifting education classes and a pre-placement examination called the Minnesota Multiphasic Personality Index. However, many other employment policies certainly influence the incidence of work-related injuries in general. Certainly substance abuse screening has had a tremendous impact on reducing the incidence of work-related injuries for those companies with aggressive policies. In addition, during the last six years, many state and federal laws have been passed that also affect the incidence of work-related injuries and job safety. Specifically, the Americans with Disabilities Act (ADA) and workers’ compensation reform have had a tremendous impact on the reporting and treatment of work-related injuries. Over the last six years, the companies operating in the state of Texas have benefited from a reduction in workers’ compensation litigation from 98% of claims to only 5% of claims.
The ADA specifically states that it is the company, not the doctor or attorney, that determines work status. Companies with modified duty positions now have injured employees working instead of sitting home. Secondary gain from the reporting of work-related injuries has all but disappeared.
Also, the treatment of low-back injuries now means mobilization instead of bed rest. This factor has had a tremendous impact on the cost of back pain and certainly resulted in a dramatic reduction in lost-time cases.
So I am left wondering what has happened to Home Depot’s injury rates for other injuries such as shoulder sprains, knee sprains, ankle sprains, and wrist sprains. Was the "decline" in low-back injuries measured in the total number of injuries, the total cost per injury, or the total number of lost-time injuries? Was the decline in back injuries part of an overall decline in injuries that could not possibly be attributed to back belts?
As an example of why the Home Depot injury reductions may not be as impressive as they might seem, consider the experience of the City of Corpus Christi, TX, for which I am the medical director. The city is a self-insured employer and has the precise data for injuries dating back for many years. The city’s work force has remained stable at approximately 3,000 employees. During this interval, hiring and firing decisions have remained reasonably fixed by the Civil Service Commission. The city does not have a drug policy for its workers except as mandated by federal Department of Transportation rules.
The city has a very aggressive return-to-work policy and utilizes a weekly disability review committee meeting to place employees that have been injured and cannot continue in their previous positions. Safety is not just a slogan but a way of life for city employees. The city employees do not wear back belts.
Over the last six years ,the city has seen a reduction in workers’ compensation costs from $11 million in 1990, to $500,000 in 1996. I also am the director of many other large and small employers throughout south Texas, so I know that the city of Corpus Christi’s experience is not the exception but rather the rule, as it pertains to workers’ compensation management.
I tell employers that back support belts are the occupational equivalent of pet rocks they were extremely popular for a brief period in history and yet completely worthless. If Home Depot is realizing only a one-third reduction in back injuries in the state of Texas, perhaps they should look at what they are doing wrong.
David G. Williams, MD
South Texas Occupational Health Clinic
Corpus Christi, TX
Froom P, Melamed S, Kristal-Boneh E, et al. Industrial accidents are related to relative body weight: the Israeli CORDIS study. Occup Environ Med 1996; 53:832-835.
Overweight workers are much more likely to suffer on-the-job injuries than other workers, according to these researchers from the Sackler School of Medicine in Tel Aviv, Israel.
They studied 3,801 men for two years to determine how a number of different factors, including weight, could be correlated to their injury rates. In addition to height and weight, the other factors included fatigue, type A personality, total night time sleep, job satisfaction, somatic complaints, smoking, and education levels. There were 870 reported accidents concerning 707 of the workers during the two years.
The main finding of the study was that an increased body mass index (BMI) increased the risk of reported multiple industrial accidents but not single industrial accidents. The effect was valid even after adjusting for the ergonomic stress levels of different work sites. (BMI is the workers’ weight in kilograms divided by height in meters squared.)
Those workers in the highest BMI quartile were 4.6 times more likely to suffer two or more industrial accidents in the two-year study period. While an increased BMI also was associated with increasing age, less smoking, and decreased sleep hours, those factors did not appear to account for the increase in accidents.
The researchers theorize that workers with an increased BMI are more fatigued from poor sleep patterns, less mobile, and have more chronic diseases. t
Bell NS, Mangione TW, Howland J, et al. Worksite barriers to the effective management of alcohol problems. JOEM 1996; 38:1,213-1,219.
The individual characteristics of a workplace will greatly affect how well an alcohol- management program works, so occupational health providers should tailor the program to the needs of an individual client. Intervening in a worker’s apparent alcohol problem will be most difficult for female managers, managers in larger worksites, and first-line supervisors, according to these researchers from Boston.
A survey of 7,255 supervisors in 114 worksites across seven major corporation revealed that the supervisors felt the most significant barriers to alcohol intervention were "individual," rather than "interpersonal" or "organizational." The latter two categories refer to barriers that are determined by company policies and attitudes, such as "the company is tough on illicit drugs but soft on alcohol."
The more influential "individual" barriers were items such as "job assignments are so fluid that managers don’t have time to get to know people they manage before they move on," and "managers don’t have enough training in how to confront employees’ performance problems."
The greatest challenge is faced by female managers supervising primarily male subordinates. Male managers supervising primarily female workers experienced the least problems in confronting subordinates about alcohol problems.
The researchers suggest that occupational health providers take such factors into consideration when designing an alcohol intervention program for a company. The study results prove that there is no one approach that will work best for all companies. t
Vinger PF, Parver L, Alfaro D, et al. Shatter resistance of spectacle lenses. JAMA 1997; 8:142-144.
Almost all types of eyewear, both prescription and safety glasses, are less resistant to shattering on impact than manufacturers claim, according to this study from Tufts Medical School in Medford, MA, and several other institutions.
The researchers evaluated the relative strength and shatter resistance of spectacle lenses currently used in sunglasses, dress (prescription), sports, and industrial eyewear. All of the lenses were subjected to tests of varying force from five projectiles air gun pellets, golf balls, tennis balls, lacrosse balls, and baseballs. The dress and industrial lenses made from glass, allyl resin plastic, and high-index plastic all shattered at impact energies less than those expected to be encountered during regular use.
Polycarbonate lenses fared much better, resisting more than the impact that would be encountered in regular use.
The industrial safety lenses made of glass or allyl resin plastic were more impact resistant than their dress counterparts, but they still shattered at the usual speeds of the objects tested. Allyl resin plastic lenses were not more impact resistant than glass lenses. The allyl resin lenses tended to shatter when the velocity of the tennis ball exceeded 55 mph. Glass lenses did not shatter until the tennis ball exceeded 89 mph. High-index plastic lenses with a center thickness of 1 mm shattered at tennis ball velocities exceeding 40 mph.
All of the glass, allyl resin, and high-index plastic lenses shattered when hit by a baseball at 94 mph. None of the polycarbonate lenses shattered in that test, even when hit at the baseball’s top speed of 135 mph.
The researchers suggest that current regulations and standards concerning the shatter resistance of eyewear are insufficient and should be reevaluated. "Our findings suggest that many currently prescribed eyeglasses that conform to prevailing standards may pose a potential health hazard and that properly designed eyewear has the potential to act as a protective shield," they write.
Improper eyewear can convert blunt trauma into penetrating ocular injury and permanent visual impairment, they warn. A study in Canada recently found that over a 10-year period, 3.6% of 446 cases of penetrating ocular injury were attributable to shattered spectacle lenses. t
Henning RA, Jacques P, Kissel GV, et al. Frequent short rest breaks from computer work: Effects on productivity and well-being at two field sites. Ergonomics 1997; 40:78-91.
Frequent short breaks from continuous computer work can improve worker productivity and well-being as long as the breaks are coordinated well with demands of the workplace, according to these researchers from the University of Connecticut in Storrs.
They studied 92 workers at two sites of a large insurance company. The workers at both sites had been working on a computer for an average of four years. They worked a minimum of 7.5 hours a day, five days a week, in a flex-time schedule. They had 30 minutes for lunch and a 15-minute break in both the morning and evening. They were allowed to leave their workstations for other reasons also.
The researchers added structured rest breaks of 15 seconds to three minutes long, spaced every six to 10 minutes throughout the work day. Some of the operators were allowed to do whatever they wanted during the breaks, while others were asked to perform stretching exercises. Several factors affecting comfort and productivity were measured.
The rest breaks improved eye, leg, and foot comfort when the breaks included stretching exercises. The employees favored three-minute breaks over shorter ones. The breaks had a "relatively benign effect on worker productivity in the present study, tending to increase rather than decrease productivity."
The effect on comfort and productivity could have been greater if the rest breaks had been more carefully integrated into the type of work performed at the insurance company. The test subjects had to perform difficult tasks and were expected to complete a high number with minimal errors. So when a break was scheduled every 15 minutes, for instance, the worker might be reluctant to take the break if it meant interrupting a task that required concentration. Workers in the study were not forced to take the breaks.
The researchers suggest that it is more effective to allow workers to take breaks when they feel they work best into their work schedule, while still encouraging or requiring them to take a certain number of breaks within a time period.
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