Laser scanners have speeded up supermarket checkout lines in the past decade, but they have produced a lot of pain and suffering among the clerks who run them.
Repeatedly pulling and tugging thousands of items of all sizes over the checkout scanners has spawned a growing epidemic of repetitive stress injuries among the nation's 800,000 grocery checkout clerks.
"It's become a big problem," said William Marris, an Ohio State University bio-dynamics engineer who wired up and monitored checkout clerks' movements in a lengthy study of the ergonomics of the checkout counter.
Indeed, in the past 15 years, American grocers have moved through six generations of new and improved laser scanners that ring up prices in the blink of an eye. But the scanners have been installed in no less than 19 different styles of checkout stations, many of which remain rooted in the old ways of doing things.
Meanwhile, repetitive stress disorders such as carpal tunnel syndrome have risen from 18 percent to 69 percent of grocers' reported annual on-the-job injuries. And the federal Occupational Health and Safety Administration levied $91-million in fines against grocers in 1991, the year the study began.
Repetitive stress injuries are caused by wear and tear on the tendons of the forearms, shoulders and wrist. Carpal tunnel syndrome is a numbness or sharp tingling sensation that radiates from the wrist where the tendons that work the fingers and thumb have irritated nerve endings. People who suffer from it sometimes lose the sense of touch in part of their hand.
The Food Marketing Institute has been bankrolling extensive studies of the biomechanics of the checkout counter to come up with some solutions. The final report will not be released until May. But some of the principals in the effort were in Tampa on Monday to outline preliminary findings that call for revised training and new types of work stations for checkout counters.
Some of the findings are:
Most repetitive stress injuries are caused by too much bending of the wrists to pull items over scanners. The risk of injury is considered low if done for less than 20 hours a week but rises dramatically beyond that.
Many people (14 percent of the female population) are predisposed to suffer repetitive stress disorders even without the kind of work that aggravates the condition. Such people include those with arthritis or gout, women using oral contraceptives, pregnant women or those who have had a hysterectomy.
Checkout work stations are now all uniformly built for people about 5 feet 6. That means people far shorter or far taller must adapt their bodies to make up the difference and risk injury. The study will recommend checkout counters that are adjustable (but cost about four times what today's models run) so they can be raised or lowered.
Checkout work stations in which the cashier faces the customer while scanning are not only the safest but also allow clerks to process more items per minute than other setups.
Checkout systems that keep clerks from having to make repeated pinching motions with a thumb and forefinger are preferable. That's a drawback to paper shopping bags and one reason why today's plastic grocery bags were developed with handles.
Giving checkout clerks a chair would be little help because standing gives clerks the freedom to bend and twist. Checkout clerks in Europe usually sit in swivel chairs as they tug items over the scanners but American researchers decided that slowed down checkout too much.
"Besides, that ends up causing back and shoulder problems," said Marris.