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Safety Meeting Presentation: Part I. Department of Occupational Safety and Health Executive Vice President’s Office Communications Workers of America, AFL-CIO. Objectives of this program.

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Safety Meeting Presentation: Part I

Department of Occupational Safety and Health

Executive Vice President’s Office

Communications Workers of America, AFL-CIO


Objectives of this program

  • The focus of this program is on the hand tools you use every day on your job (cutters, pliers, pickabonds, punch-on tools). You might never have realized it, but the design of these tools or the way you use them might actually be hurting you, bit by bit. In this program, we want to make you aware of the key roles tool design and tool use play in repetitive motion illnesses or musculoskeletal disorders (MSDs), what can be done, and what you can do about them. Here’s how we’ve organized this program.

    - What exactly are musculoskeletal disorders (MSDs)?

    - What risk factors are associated with developing MSDs ?

    - Some commonly-used hand tools used by field techs and the risk factors they present.

    - A checklist to help you spot design problems with hand tools.

    - Application of this checklist to a variety of commonly-used hand tools.

    - A checklist to help you identify problems associated with hand tool use.

    - Examples of how this checklist can be used.

    - - What you can do about problems you document using these checklists.


Is it the way they’re designed, the way they’re used, or both?

A poorly designed hand tool, even if you think you’re using it correctly, can increase your risk of developing a repetitive stress injury.

Even if you’re using a correctly-designed hand tool, you may be using it in such a way that you’restill putting yourself at injury.

Reducing injury risk = well-designed tools + proper tool use


What are musculoskeletal disorders?

  • Musculoskeletal Disorders (MSDs) aren’t caused by a single accident or trauma, like falling off a ladder or cutting yourself with a knife. You can pretty easily tell you’ve been hurt by the blood, bruise, or broken bone.

  • MSDs are caused by repeated exposure to traumas. Unfortunately, we don’t know exactly how many “repeats” it takes to cause a particular illness. Unlike single trauma injuries, you don’t generally feel overwhelming pain or see blood. If you experience symptoms, they may include sharp or aching pain, stiffness or soreness, tingling or numbness, swelling, or even sometimes tiredness or loss of coordination. Unfortunately, these symptoms are easily confused with other ailments, which makes them difficult to detect and treat.

  • Like many diseases, there are risk factors associated with developing these MSDs. The good news is that we have some degree of control over these four risk factors, so we can do something to minimize the chance of an MSD occurring:

    - Force

    - Repetition

    - Posture

    - Contact stressors


Risk factor #1: Force

  • We can look at force in at least two ways in connection with hand tools:

    - How much force is required to grip and use a tool?

    - What is the weight of the tool?

  • The gripping force is particularly important because the longer we have to apply force to grip, the more fatigued our hand and arm muscles become, which affects the blood supply and contributes to muscle fatigue. Gripping force also is related to the dimensions of the grip (ask anybody who has ever had writer’s cramp), frictional characteristics of the handle, the sharpness of the blade (for cutting tools), and whether gloves are used (glove use will require more gripping force).

  • The weight of the tool can also create muscle fatigue problems. Holding a heavy tool in place while you are in a fixed position for long periods of time can also be fatiguing. Awkward postures further aggravate the situation.


Risk factor #2: Repetition

  • Repetition simply means the more often you do something, particularly in connection with a poor posture, excess force, or a contact stressor, the more likely you are to increase your risk of an MSD. Unfortunately, we don’t know exactly how many repetitions it takes to produce a particular symptom or illness.

  • One NIOSH study found workers with jobs that lasted less than half a minute per work cycle were three times as likely to develop MSDs as compared with workers having longer cycle jobs.

  • For example, a frame attendant’s job can involve repetitive activities such as attaching leads to a jumper. Repeated use of a poorly-designed hand tool, such as the punch-on tool shown in the slide below, can increase the risk of an MSD.


Risk factor #3: Posture

  • Stand up right now! Find your most comfortable posture. Notice that your arms are at your side, your back and neck are straight, and your wrists and elbows are flat against your side. This is your neutral or natural posture. Any significant deviation from this posture, particularly where the other risk factors--force, repetition, or contact stressors are involved--stresses your muscles, tendons, ligaments, nerves, and blood vessels.

  • According to the National Institute for Occupational Safety and Health (NIOSH) of the U.S. Centers for Disease Control, the postures most often associated with upper body MSDs are:

    - Wrist flexion (bending your wrist down—away from you)

    - Wrist extension (bending your wrist up- towards you)

    - Ulnar deviation (bending your wrist laterally towards your little finger)

    - Radial deviation (bending your wrist laterally towards your thumb)

    - Pinch grip (gripping tools with your thumb and finger tips)

    - Wrist and elbow rotation (like wringing the water out of clothes)

    - Shoulder abduction (your arms are pulled away from your shoulder, like “winging”)

    - Working with your hands above your shoulder


Example of wrist extension and flexion

  • The slide above shows wrist flexion of the left hand (you can see the thumb). With your arm out in front of you, with your palms facing down, bend your wrist toward the floor. This is flexion.

  • Extension, on the “other hand”, is the opposite of flexion. Again with your arm out in front of you, with your palms facing down, bend your wrist toward the ceiling. This is extension.

  • See if you can think of at least two times during the day when your wrists are extended or flexed.


Ulnar and radial deviation

Hold your arms directly in front of you, with your palms facing each other (handshake position). Now bend your wrists down so your pinkies are pointing towards the floor. This is ulnar deviation as also seen in the photo below. Typing on a standard keyboard also requires ulnar deviation.

If you repeat the exercise but move your hands upward (with your pinkies pointing toward the ceiling, you have radial deviation).


Wrist and elbow rotation

Hands wringing (like wringing water out of clothes) is a motion we often

see when using a can wrench to open a pedestal, as pictured below.


Pinch Grip

Grasping materials or objects with the tips of the fingers and thumb requires the use of smaller muscles in the forearm and arm. Using these smaller muscles to exert large forces results in more rapid fatigue and tendon stress. Also, using a pinch grip with the wrist flexed further reduces the strength of the muscles. For example, the technician below is using a pinch grip with both hands as he grasps the sand paper and runs it over the sheath to roughen the surface.


Winging

Note how the left elbow is positioned well away from the side of

the body

(the neutral position) as the technicianis using a torque wrench to tighten this bolt.


Arm(s) above the shoulder

Note how the left arm and hand is above shoulder height. Working with the arm(s) and hand(s) above shoulder height for long periods (static loading) decreases blood flow to the shoulder muscles and increases fatigue more rapidly.


Risk factor #4: Contact stressors

When ever a tool rests against body parts, such as the palm pinch with the right handed punch-on tool in the slide below, a contact stressor is created. These contact stressors can affect both the blood supply and thenerves.


Contact Stress

Note how the right-handed loop of these snips is pressing into the base of the palm, right near the base of the median nerve!


Part II: Tool design/selection checklist

In order for union representatives, workers, managers, and others to evaluate the design of hand tools, a checklist has been developed over time by ergonomists and other experts from universities, government, companies, and unions. It is an attempt to incorporate principles of ergonomic design directed at minimizing or eliminating the risk factors we’ve been talking about.

At least seven (7) factors are examined in this worksheet. You should have a copy of this worksheet in front of you now. We will use this worksheet to evaluate every hand tool and determine what we should do about each tool: keep it, find a substitute, modify it, or replace it.

A description of each of the criteria follows the checklist.



Tool design/selection criteria: Handle length and diameter

  • The length of the handle, experts agree, should be a minimum of four (4) inches (However, also be aware tools with longer handles will usually also have a larger grip span). If gloves will be worn by the tool user, the handle should be a minimum of four and one-half inches long. This way, the handle does not end inside the palm when gripped, thus eliminating a contact stressor.

  • The diameter of the handle depends upon how the tool is gripped.

    • - If a precision grip is used (e.g. a pencil), the diameter should fall between 0.3 and 0.6 inches).

    • - If a power grip is used (the way you hold a baseball bat), the diameter should fall between 1.25 and 2.00 inches).

  • Remember, the diameter is the distance across the handle of the tool.

Handle length

Handle diameter


Tool design/selection criteria: Handle span and return

  • The handle span is the distance across from one handle to the other handle of the two-handled tool (pliers, cutters, crimpers, etc.). The distance between the handles at the point where the greatest amount of force is applied should between 2 and 3 inches. The outside distance between handles should not exceed 3.5 inches for a grip between the third finger and the palm at the base of your thumb; if the span is greater than this, it significantly increases the difficulty for a person with a small hand to use this tool.


Tool design/selection criteria: Recessed hand grips and flange

  • Form-fitting handles may look and perhaps even feel comfortable at times, but not every tool user’s fingers will fit perfectly into these recesses. When this happens, some of the gripping force that is supposed to be transferred into the hollows of the handle is instead transferred into the ridges themselves, thus creating a contact stressor and perhaps affecting your circulatory and nervous system. The same applies to screwdrivers with knurls (recesses). One advantage of a tool with knurls is that the knurls increase the friction between the hand and the handle, thus requiring less hand grip force to hold the tool.

  • A flange at the base of the handle prevents the tool from slipping accidentally out of your hand when you’re using it. Thus, you don’t have to grip the tool as hard, which further reduces the contact stressor.

In some cases, the knurls may hurt rather than

help.

Form-fitting handles


The grip itself flange

  • Minimize sharp edges on the tool. They create contact stressors.

  • The handle should be coated with a slightly compressible material (but not too soft) to improve the grip and reduce gripping force requirements.

  • The material coating the handle should be non-slip.

  • The material coating the handle should be non-conductive.

  • Tools should be appropriate for both right- and left-handed workers.

    Note the well-padded handles on this tool - They’re non-slip, compressible, and non-conducting.




How do we use the results of the tool design/selection checklist?

  • Now that we’ve filled out the tool design evaluation checklist on several tools, what do we do with the results? First of all, highlight (use a highlighter pen) those of the seven areas where the hand tools don’t measure up. Then, for each case so identified, ask yourself:

  • Can we modify the tool? Usually this involves adding a compressible, non-conductive, non-slip gripping material.

  • Can we find a safer substitute? Maybe you already have a better tool in the shop or in your tool box. You can put green tape around those tools which “pass inspection”, yellow around those which are “borderline”, and red around those which “should not be used”.

  • Should we simply replace it? If so, you can use the completed checklist as documentation for your request.


Part III: Tool use checklist checklist?

  • The tool use checklist helps us to determine what risk factors are present when a particular tool is being used. We’ve already analyzed the tool itself; now we have to see how it is used and document the presence of risk factors.

  • Here’s a list of the risk factors we are looking for:

    • High hand force

    • Winging

    • Arm(s) above the shoulder

    • Extended or flexed wrists

    • Ulnar or radial deviation

    • Pinch-grip

    • Hands-wringing

    • Trigger finger

    • Contact stress

    • Vibration



High Hand Force: Pinch grip checklist?

The technician below is using a pinch grip with both hands as he grasps the sand paper and runs it over the sheath to roughen the surface. A pinch grip is the grip you typically use when you grip a pencil or pen. You know what happens when you grip it for too long--you get “writers’ cramp”.


High hand force: Power grasp checklist?Notice how this technician uses both hands to grasp the snips handles as she cuts through the cable sheath. This is an indication that excessive hand force is required.


Winging checklist?

Note how the left elbow is positioned well away from the side ofthe body (the neutral position) as the technician is using a torque wrench to tighten this bolt.


Arm(s) above the shoulder checklist?Note how the technician’s left arm and hand are above shoulder height. Working with the arm(s) and hand(s) above shoulder height for long periods (static loading) decreases blood flow to the shoulder muscles and increases fatigue more rapidly.


  • The slide below shows wrist flexion of the left hand (you can see the thumb).

    With your arm out in front of you, with your palms facing down, bend your wrist

    toward the floor. This is flexion.

  • Extension, on the “other hand”, is the opposite of flexion. Again with your arm

    out in front of you, with your palms facing down, bend yourwrist toward the

    ceiling. This is extension.

  • See if you can think of at least two times during the day when your wrists are

    extended or flexed.


Ulnar and radial deviation can see the thumb).

Hold your arms directly in front of you, with your palms facing each other (handshake position). Now bend your wrists down so your pinkies are pointing towards the floor. This is ulnar deviation as also seen in the photo below. Typing on a standard keyboard also requires ulnar deviation.

If you repeat the exercise but move your hands upward (with your pinkies pointing toward the ceiling, you have radial deviation).


Hands-wringing can see the thumb). Hands wringing (like wringing water out of clothes) is a motion we often see with the use of a manual screwdriver, as is the case in the graphic right below. Using a well-designed power tool can eliminate this motion.


Trigger finger can see the thumb). Note here how the index finger is depressed against the trigger of the screw gun. Where this risk factor is present repetitively over a period of time, there is a risk of developing a tendinitis condition called “stenosing tendinitis” or “trigger finger”. Locking triggers or a trigger bar are preferred.


Contact stress can see the thumb). Contact stress is clearly illustrated in the slide below. Note how the upper handle (right photo below) is pressing directly into the meaty part of the palm, right at the base of the median nerve. Also the photo on the left illustrates contact stress with the palm of the hand and the end of the screwdriver handle.


Vibration can see the thumb). Certain power tools expose workers to significant amounts of vibration, as in the slide below. Repetition also plays a key role here. Lighter and counter-balanced tools, as well as vibration-absorbing coatings on the handles help reduce vibration. Minimizing exposure in wet, cold environments and selecting tools which have less vibration also helps. Redesigning the tool to lower vibrations and using vibration dampening grips on handles helps reduce risk factors.


Now, let’s try to use the checklist on several different tool uses.

  • Take out four blank tool use checklist forms.

  • Observe each of the next slides and complete the checklist for each slide.

  • The slides depict the following scenes:

    - Frame attendant using a punch-on tool

    - Splicer using a screwdriver

    - Installer using a screwdriver

    - Splicer cutting a cable sheath


Tool use checklist #1: Frame attendant with punch-on tool tool uses.

Now, complete the Checklist on the next page.


#1 Frame attendant tool uses.


Tool use checklist #2: Splicer using screwdriver tool uses.

Now, complete the Checklist on the next page.



Tool use checklist #3: Installer using screwdriver tool uses.

Now, complete the Checklist on the next page.



Tool use checklist #4: Splicer cutting cable sheath tool uses.

Now, complete the Checklist on the next page.



Using the tool use checklist: some pointers tool uses.

  • Use the checklist to coach your fellow members in how they are putting themselves at risk and what they can do to minimize the risks.

  • Work to revise job practices and work methods so that they reflectMSD risk reduction practices described in this program.

  • Tool redesign may be necessary--substitution, modification, or replacement.

  • Changes in work layout may be necessary; using adjustable fixtures, templates, jigs, stools, or other set-ups might reduce the need to work with awkward postures.

  • Job rotation and more frequent rest breaks might also be helpful in reducing the risk of repetitive use. Sometimes, it may be a more frequent change of work posture.


What you can do with problems concerning tool use tool uses.

  • Start with showing this program: watch it yourself, with your co-workers, supervisors, and managers. Show it at a safety meeting.

  • Use the tool design/selection checklist to start analyzing tools. Use the completed checklists to start modifying, substituting, and replacing tools which don’t measure up.

  • Work with your employer and union, one-on-one or through safety and health committees, to replace poorly designed tools.

  • Start collecting catalogs of tools or visit the World Wide Web or Thomas Directory.

  • The tool use checklist can help analyze jobs and use the results for coaching, revising job procedures, designing new fixtures, templates, and tools.

  • Become an advocate for ergonomics on and off the job -- not just the tools you use but how you use them.

  • Ergonomics means fitting the workplace and the tools to the worker, not the other way around. If you’re not part of the solution, you may be part of the problem!


CREDITS tool uses.

  • Photos:

    Keith Brossard, CWA Local 7800,

    Gary Mullikin, CWA Local 4630, and

    John Lund, School for Workers, University of Wisconsin

  • Written and edited by:

    John Lund, School for Workers, University of Wisconsin,

    David LeGrande, CWA Occupational Safety and Health

    Director,

    Keith Brossard, CWA Local 7800, and

    Gary Mullikin, CWA Local 4630

  • Executive Producer: David LeGrande, CWA


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