Goals. Vibration I njury in the Workplace. Definitions HAVS. HAVS (cont.) HAVS (Cont.)

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1 Goals Vibration I njury in the Workplace Stewart Russell D.O.,M.P.H. October, 2014 OMED Seattle Be able to define the types of vibration injury Recognize the probable causes of vibration injury Interventions when injury is diagnosed Mitigation techniques to prevent injury from occurring Definitions Two types of vibration injury Hand Arm Vibration Syndrome (HAVS) Whole-Body Vibration (WBV) These can be acute or chronic in nature. While these conditions involve the worker s total health picture, I will deal with these one at a time. HAVS Vibration can be explained as the back and forth motion produced by objects such as tools, machinery, and equipment. This has two components: Frequency (repeat rate) Amplitude (displacement) Some objects vibrate by design such as jackhammers or sanders, and some due to defects or malfunctioning HAVS (cont.) When a worker uses or handles a vibrating object, the vibration is transmitted to the hands and arms, resulting in hand/arm vibration. Both frequency and amplitude play a role in injury. Who is at risk? Any person who operates powered equipment with high frequency vibration or high impact for extended periods of time is at risk for HAVS. Examples are users of chainsaws, grinders, jackhammers, impact wrenches, or sanders. Industries commonly at risk-construction, Mining, Automotive repair, Forestry, Foundry/Smelter, and Manufacturing. Estimate 2 million workers. Smokers are at greater risk than non-smokers M-1

2 Symptoms of HAVS Numbness, tingling, finger blanching(vibration white-finger), decreased hand sensation and dexterity, and decreased grip strength. These findings are progressive if the exposure continues. Initial symptoms of numbness and tingling may be ignored until one finger may blanch in response to cold exposure, which can be followed by multiple fingers, and both hands may be involved. Cold weather and smoking are important aggravating factors. Example: Young males, many of whom smoke cigarettes, working outside in winter, using jackhammers in road construction have multiple risk factors predisposing them to HAVS. Similarly, forestry workers using chainsaws outside in cold conditions are very susceptible to HAVS. Degrees of HAVS Mild=Occasional attacks affecting the tips of one or more fingers Moderate=Occasional attacks affecting the tips and knuckles of most fingers Severe=Frequent attacks affecting all sections of most fingers Very Severe=As in severe, but with skin alterations in the fingertips Adverse health effects Continuous exposure results in constriction of blood vessels in the hands and arms, thereby cutting off blood supply to the fingers and hands. This causes numbness, blanching, and tingling in the affected part. HAVS may also have a neurological component that can mimic carpal tunnel syndrome. Stiffness in the hands and wrists can be due to a musculoskeletal component. The amount of damage to the blood vessels is proportional to the duration of the exposure and the intensity of the vibration. This process is generally slow and cumulative. However, once the condition is present, continued hazardous vibration exposure increases the risk of permanent injury and loss of hand function. Ceasing exposure will generally stop the progression and up to 40% of workers would be expected to note some improvement. Preventive Measures: Identify the jobs or occupations that involve the use of powered hand tools Evaluate the extent of use including duration and intensity of vibration Determine if any workers are showing symptoms of HAVS If vibration is a concern, develop a code of practice for use of tools, equipment or machinery M-2

3 Code of Practice should include: Tool selection Alternate tools and methods for certain jobs Train workers on proper use and handling of tools, equipment, and the warning signs of HAVS Mandatory rest periods of 10 minutes every hour of tool use Regular inspection and maintenance of tools Selection and use of anti-vibration gloves Pre-placement and periodic medical evaluations of workers exposed to vibration Workers who suffer from an advanced stage of HAVS should be removed permanently from ongoing exposure WHOLE BODY VIBRATION Growing concern in industry, traffic, and other branches of the economy. Estimate 8 million workers. In spite of increasing exposure to vibration, most medical practices do not pay adequate attention to the health effects of whole-body vibration. Need to evaluate frequency, amplitude, velocity, and acceleration. In an adequate evaluation, need to assess weighted average value, peak values, rating, and weighting procedure of vibration measurement. Need also to note exposure from vibration direction, exposure time, transmission and dissipation. The most pronounced long-term effect of wholebody vibration is damage to the spine. The most frequent is the lumbar spine where spinal deformation, lumbago, and sciatica can develop. Possible causes are mechanical overload and metabolic changes in the intervertebral disc. Other organ systems can be affected and include peripheral and autonomic nervous system, vestibular, vascular, digestive and female reproductive systems. Risk assessment is based on evaluation of vibration exposure and individual response. Health risks increase with intensity and duration of vibration exposure. This is no different than HAVS. Forced sitting posture and heavy physical work are additional factors involved with risk. The main problems in diagnosing whole-body vibration syndrome are differentiating this from aging changes in the spine. M-3

4 Only long-term medical surveillance can guarantee proper assessment of the damage induced by whole-body vibration. For workers exposed to vibration, preplacement and periodic examinations are recommended. These should include a basic medical examination and an x-ray of the lumbar spine, at a minimum. The US Navy has determined that vertical vibration in the range of 4 Hz and side to side vibration of 1-2 Hz, will literally cause an operator to be unable to control a vehicle. Therefore, proper design of equipment (engineering controls) is essentially to the safe operation of any equipment by humans. WBV and HAVS Prevention-What can be done to prevent or mitigate these conditions Air ride seat installation that attenuates vertical, front to back, and side to side vibrations. Estimated cost is $ per seat. Design anti-vibration tools to decrease exposure (engineering controls) Cost varies with tool type. Use of anti-vibration full-finger gloves (personal protective equipment) Cost $6-40/pair. Examples For example, if a young person came to work for a construction company and was evaluated for a job running heavy machinery, an examination of the low back and possibly an x- ray can be indicated. Let s say the x-ray demonstrated bilateral pars defects and a Grade I spondylolisthesis. What can be done to address this situation? Examples Example-You hire a 55-year-old laborer who is sent by his union to work on a job replacing concrete walls in a paper mill. The job description indicates he is going to have to use a jackhammer most of the day. You have a post-offer physical performed and the physician notes positive Tinel s and Phalen s maneuvers and that he complains of low back pain. What is your course of action? The health effects of vibration on the upper extremities of workers, Global Virtual Conference, April 8-12, 2013, Monica Lopez-Alonso et.al. The hand-arm vibration syndrome-diagnosis, assessment and objective tests: a review. W. Taylor. Journal of the Royal Society of Medicine, volume 86, February 1993, pages M-4

5 Bad Vibrations: Hand-Arm Vibration Exposure and HAVS Prevention, Cliff Wolcott, ehstoday.com/standards/osha/ehs/imp Vibration-Health Effects, Canadian Centre for Occupational Health and Safety, 10/21/2008. Navy Safety Center-Acquisition Safety- Vibration, 4/23/2014, M-5