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

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 flexes and constricts as the hand is moved. The median nerve passes through the carpal tunnel just before entering the hand. Hand movement compresses the median nerve and its surrounding tissue. Gradually, the nerve becomes swollen and trapped, causing the condition known as CTS. This injury is associated with forceful repetitive motions of the wrists and exposure to vibration. (8) Treating surgeons have remarked during litigation in Connecticut that the median nerve in cases of vibration-induced injury appear more thickened and woody than those in traditional CTS cases, as when the condition is caused by keyboard use.

Studies have shown that vibration affects the hand's neuromuscular mechanisms that control grip force: Workers using vibrating tools often grip the handle of the machine harder than needed. Excessive grip force is known to contribute to the development of CTS. (9)

All estimated 1.45 million American workers use vibrating tools. The National Institute for Occupational Safety and Health (NIOSH) reported that between 6 percent and 100 percent of workers exposed to vibration develop the condition, with the average study showing a rate of 50 percent. (10) Studies of forestry workers who use chain saws found that up to 91 percent develop the condition within five years. (11)

In the mid-1980s, the first of over 1,000 cases of hand-arm vibration syndrome in workers at the Electric Boat Corp. in Groton, Connecticut, was diagnosed. Studies by the Yale Occupational and Environmental Medicine Program revealed that all of the grinders at the occupational health clinic had damaged nerves and blood vessels in their hands. (12) Hundreds of lawsuits and workers' compensation claims followed. (13) Other cases were pursued in Mississippi, Oregon, and Texas. (14)

Several standard-setting bodies, including the American Conference of Governmental Industrial Hygienists, have recommended limits on vibration exposure. (15) The International Organization for Standardization (ISO) and the American National Standards Institute's standards for measuring vibration include appendices recommending exposure limits and showing that the incidence of disease increases as exposure increases. (16)

Despite these recommendations and a flood of reports establishing that hand-arm vibration injuries are prevalent in the United States, the pneumatic tool industry and the federal government have generally failed to act. Most pneumatic tools still lack vibration-reduction devices, and federal regulation efforts seem to have died with the Bush administration's decision to kill the Occupational Safety and Health Administration's ergonomic standard, which would have regulated the causes of repetitive stress injuries. As a result, thousands of workers continue to develop hand-arm vibration syndrome every year.

Industry inaction

Discovery in litigation has revealed that the pneumatic tool industry has known at least since the 1970s that its machines produce vibration injuries. The Compressed Air and Gas Institute (CAGI), a U.S. trade organization, and Pneurop, its European counterpart, met regularly to discuss the hazard and the economic impact that would result from advising consumers of vibration dangers. Documents suggest that they worked jointly to discourage the placement of warnings on their tools. (17)

The industry also fought the development of standard warning symbols for vibration. It suggested drafting warnings that "share responsibility" with the employer and employee. Manufacturers also argued that industry members should develop standard warnings that don't create a "competitive disadvantage" by suggesting the equipment is unsafe. (18)

In the late 1970s, as the ISO neared publication of its standards for measuring vibration, Pneurop completed a set of tests showing that it could measure vibration levels accurately. The European group proposed that CAGI share this information with NIOSH, which had recently reported the results of a series of vibration tests that "were unrealistically high" due to flawed test methods. (19)

The trade organizations and manufacturers weighed whether giving NIOSH the correct data was in their best interests. They knew that vibration was causing white finger. The only issue was how much vibration it took to cause the injury. Correcting the NIOSH error to show that even lower vibration levels were harmful could hurt the industry, they thought. They decided to withhold the information from NIOSH and let workers continue to be injured. (20) The decision to withhold data and cover up the hazard, combined with later decisions to withhold warnings, are the basis for conspiracy, racketeering, and punitive damages claims.

In the early 1990s, British health authorities became concerned about the number of vibration injuries and contacted the British Compressed Air Society, a trade association of compressed air machine manufacturers, to suggest that manufacturers place vibration warnings on pneumatic tools and develop a standard antivibration symbol. European and U.S. tool manufacturers voted to not put warnings on their tools.

Manufacturers have also ignored antivibration technology. In the mid-1990s, Chicago Pneumatic Tool Co. developed a shock absorber that reduced vibration, but it and other manufacturers continue to sell tools without it.

Litigation strategies

Focus on causation. In a vibration injury case, the defense will try to convince the jury or workers' compensation commissioner that the injury's causes are complex and multiple and that causation is poorly understood. It will try to equate the injury with traditional CTS and argue that many people who suffer from CTS were never exposed to vibration. You and your experts should understand the similarities and differences between these injuries to determine how to present the claim.

It is true that vibration is a major cause of CTS, and if a substantial portion of the damages flow from injuries to the carpal tunnel, you may decide that you must focus the claim on those injuries. However, as noted above, doing so gives the defendant an opportunity to confuse the causation issue at trial.

If possible, put the focus elsewhere. For example, vibration is the sole or a major cause of peripheral nerve injuries below the wrist joint, and CTS does not normally result in finger blanching. You may choose to discuss only the vascular and peripheral nerve injuries, which are more easily attributable to vibration.

Concentrate on vibration-induced injury to nerves, not aggravation of CTS. If you decide to include vibration-induced median-nerve damage at the carpal tunnel, be familiar with the pathology and etiology of CTS.

Argue the claim as an employment case. Vibration-induced injuries may lead to significant wage loss, medical costs, mad physical impairment, or these losses may be limited. Nerve damage, like connective tissue injuries, is often not observable. In some cases, to ensure adequate damages are awarded, you may want to emphasize the worker's loss of a trade, which tends to resonate with juries composed of workers and their families.

Many jurors are suspicious of plaintiffs' claims, especially those involving subjective injuries. This antiplaintiff bias does not appear as often in many employment cases. In past generations, workers were loyal to their employers, and employers expected their suppliers to be loyal to workers. Collusion between employers and suppliers to disregard the safety of workers is a violation of the duty of loyalty, and it strikes many jurors as outrageous. As American industry has cut health insurance, pension programs, and other benefits, and increased downsizing and out-sourcing, many jurors have recognized that the bargain has been broken.

Many workers define their identity and personal worth by their profession. Jurors are likely to sympathize with a machinist or welder who lost his or her job--and career--because an employer and tool manufacturer preferred to replace an injured worker rather than a defective tool.

Discuss design defects. Many vibration injuries could be prevented, or at least reduced in severity, if the tools were designed properly. Jurors sometimes have difficulty understanding design defects. A broken spring is a simple defect and easily understood, but a shock absorber that was ineffectively designed is more complex and less compelling. This is particularly true if the tool passes the "pretty test"--that is, some jurors think that if the manufacturer took the care to make the tool attractive, it could not be hazardous.

Take the jurors back to the design process and explain that you are talking not only about the tool they see in front of them, but also about the tool that should have been designed and produced. Tell them: The first step in eliminating injuries is eliminating the hazard that causes them. Injuries that result from hazards that can be eliminated are not accidental. They would not occur if the hazard had not been designed into the tool.

Many jurors mistakenly believe that some risk of injury is acceptable because there is only a small chance that a person may be hurt. But the word "risk" actually describes how many injuries will occur. A one-in-a-million risk of death by electrocution from poor electrical connections in manhole covers per year means that this hazard will kill eight people each year in New York City. If a tool such as a chain saw produces vibration that causes injury in 91 out of 100 workers, the risk of injury is 91 percent.

We know how many people will be injured; only their identities are left unknown, until the diagnosis is made. It is helpful to emphasize that risk is a description of how many injuries will occur in a population, not whether injuries will result.

Explain to jurors that if the manufacturers cannot eliminate the hazard, they should at least reduce it. They should incorporate shock absorbers in vibrating tools, or use a guard to separate the worker from the vibration. The companies go to considerable effort to reduce or eliminate vibration that reduces tool life; they should do the same to reduce injury to users.

Counter blame-shifting. The defense may use several tactics to avoid responsibility and liability. For example, tool manufacturers have blamed employers and workers for failing to heed warnings hidden in the instruction manual. What they fail to point out is that in many cases, the manufacturers placed the warning in the manual rather than on the tool because they knew that it was less likely to be seen there.

Minutes from trade association meetings indicate that the members felt that the warnings' placement and language should not imply that the tool was unsafe to use and should shift blame to the employers. They proposed that the tool should bear a label instructing users to read the instruction manual before using it. If they don't, the argument goes, it's not the manufacturer's fault.

The warning should be clear, easy to see, and printed on the tool. It should describe the hazard--both the vibration and the damage it will cause.

The manufacturer may also charge that modification, alteration, or poor maintenance of the tool caused the injuries. Respond by asking the manufacturer how it intended the tool to be used. If industrial use was anticipated, the manufacturer should have designed the tool so that its safety could withstand expected wear and tear. You can also argue that most pneumatic tools produce unsafe vibration levels even when they are brand new.

A defendant may also try to shift the fault to the worker by producing research showing that cigarette smoking contributes to the severity of hand-arm vibration syndrome. Remind jurors that the vibration the machine produced, not smoking, caused the disease. The effect of smoking does not reduce the manufacturer's liability.

Also, tool manufacturers could reasonably anticipate that users will smoke, so they should not be excused for designing tools that hurt smokers. If smokers are at greater risk, the warning should indicate this and advise smokers that they should not be exposed to vibration.

Compelling accountability

The aggregate costs of work-related and repetitive-stress injuries are often underestimated because workers are forced from their trades in large numbers and must bear the costs of lost wages, benefits, and career opportunities themselves. Workers' compensation claims and products liability lawsuits are the best way to hold employers and manufacturers accountable for the damage these tools inflict--both on injured workers and on society as a whole.

If employers and manufacturers are forced to pay these costs, they often will work to eliminate the hazards, preventing physical injury to the worker and economic injury to society. If workers pay these costs, company executives merely get bigger bonuses. The lawyer's job is to make sure that the risks and costs associated with hazards are properly assigned.


(1.) Alice Hamilton, Reports of Physicians for the Bureau of Labor Statistics--A Study of Spastic Anemia in the Hands of Stonecutters, in Effect of the Air Hammer on the Hands of Stonecutters, BULL. NO. 236 (Industrial Accident & Hygiene Series No. 19) (1918).

(2.) Maria Seyring, Maladies from Work with Compressed Air Tools, 6 BULL. HYGIENE 25, 1 Arch. Gewerbehyg. (Berlin) 359-75 (1931).

(3.) D. Hunter et al., Clinical Effects of Use of Pneumatic Tools, 2 BRIT. J. INDUS. MED. 10 (1945).

(4.) M.D. Grounds, Raynaud's Phenomenon in Users of Chain Saws, 1 MED. J. AUSTL. 270 (1964).

(5.) See, e.g., NAT'L SWEDISH BD. OF SAFETY, HEALTH REG 71:1 (1971).

(6.) J.H. Mills, Pneumatic Hammer Disease in Unusual Location, 41 N.W. MED. 282 (1942).

(7.) M.A. Farkkilla & O.S. Korhonen, Carpal Tunnel Syndrome Among Forest Workers, in HAND-ARM SYNDROME 263-65 (Akira Okeda et al. eds., 1990).

(8.) See G. Wieslander et al., Carpal Tunnel Syndrome (CTS) and Exposure to Vibration, Repetitive Wrist Motions and Heavy Manual Work: A Case-Referent Study, 46 BRIT. J. INDUS. MED. 43 (1989).

(9.) Robert G. Radwin, Neuromuscular Effects of Vibrating Tools on Grip Exertions, Tactility, Comfort and Fatigue (1986) (unpublished dissertation, University of Michigan) (on file with author).


(11.) Grounds, supra note 4, at 270-72.

(12.) M. Cherniack et al., Detailed Chronological Assessment of Neurological Function in Symptomatic Shipyard Workers, 47 BRIT. J. INDUS. MED. 566-72 (1990).

(13.) See, e.g., Potter v. Chi. Pneumatic Tool Co., 694A.2d 1319 (Conn. 1997).

(14.) See, e.g., Abney v. Ingersol-Rand Co., No. 93-3000 (Miss., Jackson County Cir. Ct.); Sheav. Chi. Pneumatic Tool Co., 990 E2d 912 (Or. 1999); Anderson v. Ingersol-Rand Co., No. 96-CV-0663 (Tex., Galveston County Dist. Ct.).



(17.) Meeting Minutes, Indust. Tools Technical Subcomm., British Compressed Air Soc'y (Oct. 21 and Dec. 16, 1982) (on file with author).

(18.) Meeting Minutes, Pneurop, June 6, 1980 (on file with author).

(19.) Meeting Minutes, Pneurop Subcomm. No. 8, Working Group on Vibration, British Compressed Air Soc'y (May 29-30, 1979) (on file with author).

(20.) Meeting Minutes, Engineering Comm., Compressed Air & Gas Inst. (Jan. 11, 1979) (on file with author).

STEPHEN C. EMBRY is a partner with the law firm of Embry & Neusner in Groton, Connecticut.
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Author:Embry, Stephen C.
Date:Aug 1, 2004
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