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Bad vibrations: industrial tools can cause devastating hand and arm injuries. Help protect workers by holding manufacturers liable.

Article Excerpt
Grinding machines, chippers, dental drills, glass cutters, and impact wrenches are a few of the modern tools that, when used as intended, produce high levels of vibration that gradually damage the nerves and blood vessels in users' hands. Regular use of such tools over a few years can produce a crippling condition known as "hand-arm vibration syndrome" or "white finger."

White finger was first described in the United States by Dr. Alice Hamilton, who in 1918 investigated an outbreak of hand injuries in Bedford, Indiana, that appeared shortly after pneumatic air hammers were introduced in the stone-cutting industry. She found that 89 percent of the workers had developed what she called "dead hand"--their hands were greenish-white and shrunken "quite like the hands of a corpse." (1)

Over the next 50 years, workers in the shipbuilding, airplane manufacturing, metal casting, and glass cutting industries developed the condition. It has been reported in users of grinding tools, (2) rivet guns, (3) and chain saws. (4) By the 1960s the problem was so widespread that some European countries began to set permissible vibration-exposure limits. (5) Design changes in Europe and the United States in chain saws, including placement of rubber isolators on handles, followed in the early 1970s, leading to a rapid reduction in the number of reported injuries.

Vibration first produces mild symptoms of tingling and numbness. These can appear after only a few hours of a task such as weed whacking. The temporary effects fade, but repeated exposure to vibration causes cumulative, permanent injury. Several months or years of exposure can damage the blood vessels in the hand. The fingers begin to blanch, or whiten, while the blood vessels in the hand spasm, preventing blood flow and depriving nerves and muscles of oxygen. Since cold weather can also provoke blanching, most workers who use vibrating tools outdoors in cold weather do not realize that their work is causing permanent injury. Physicians often misdiagnose the condition as frostbite.

If the vibration exposure continues, the blanching attacks gradually in crease in frequency, duration, and severity. Blanching is often followed by a marked red flushing of the hand as the blood vessels relax and blood pours back into the fingers, causing intense pain. Extreme cases may lead to gangrene and require amputation.

Over time, this process damages hand and wrist nerves, causing the worker to lose dexterity, sense of touch, and grip strength. The injuries may also cause reflex sympathetic dystrophy in which the blanching and weakness can occur in parts of the body not exposed to vibration. (6)

Vibration also contributes to and accelerates the development of carpal tunnel syndrome (CTS). (7) The carpal tunnel is a narrow, bony passage that...

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