ny workenvironment,including thelaboratory,

can be a source of ergonomicstress. Two factors in pipettingwhich can cause the user physicalstress are the design of the pipetteand the manner in which it isused. An ergonomically designedpipette should pose few if anydifficulties or risks to the userwho, trained in body mechanics,knows which positions and pos-tures to avoid. Awkward posturesand repetitions are not bad inthemselves, but can pose a prob-lem if stresses are cumulativeand tasks are not balanced.

Selecting your pipettes andthe manner in which they areused is a relatively simpleproject which requires little morethan applying some useful infor-mation. The investment of someresearch and training is far out-weighed by the return: improvedsafety and health in the work-place, improved productivity,reduced absenteeism and turn-over, and reduced probability ofaccidents and errors.3

Potential problemsManual action pipettes, one

of the most commonly used lab-oratory instruments, can causemuscle strain or tendon swelling,particularly if good body me-chanics are not applied whilepipetting. Manual pipetting in-volves several ergonomicstresses of the wrist, arm, and

shoulders. The stresses are typ-ically caused by repetition,awkward posture, and the exces-sive use of thumb force4 whendispensing a sample. “In addi-tion, pipetting is done in aposition where the thumb is notstable but nevertheless has towork to stabilize the grip aroundthe pipette and to press downthe button [plunger] of the pi-pette. Therefore the muscleshave to work as both mobilizingand stabilizing structures” and

are subjected to increasedstress.5 These physical stressesare further aggravated by themental pressure resulting fromthe accuracy, precision, and tim-ing demanded in many pipettingprocedures.2 Taken together,these factors put laboratorytechnicians at a great risk of de-veloping a CTD, or a cumulativetrauma disorder: one of a groupof health disorders affecting themuscles, tendons, joints, andnerves, which can cause pain

Issue 3

ergonomicsPipette use and

“Ergonomic disorders

are the fastest growing

category of work-

related illness...There

is no question that

workplace injuries are

a major factor in

bottom line

profitability across the

world...” 1

Darcor, The Cost of CTDs

■ Rotate pipetting tasks among several people.1

■ Use only the force necessary to operate the pipette; do not useexcessive force.1

■ Choose pipettes requiring the least pressure.1

■ Use shorter pipettes, which allow for decreased arm elevationand thus eliminate the use of awkward postures.1

■ Consider using electronic pipettes, which are programmableand reduce the need for excessive thumb force and repetition.2

Electronic pipettes, however, are sometimes designed with right-handed persons in mind and may be difficult for a left-handedtechnician to use.6

■ Use low profile waste receptacles for used tips. Receptaclesshould be no higher than the tops of the tubes being filled.1

■ Take short pauses of several seconds when youare unable to take a longer break.1

■ Use adjustable chairs or stools with built-in solid foot rests. Work with arms close to thebody to reduce strain on shoulders. Multipi-pettes, which are considerably stiffer thanautomatic or manual action pipettes, shouldbe used on a limited basis.1

■ Choose a pipette that fits your hand. Yourhand should cover more than half, but notthe entire, circumference of the pipette.1

19A3228A

Steps that you can take to reduce the risk of developinga cumulative trauma disorder include:

What are some of the more common cumulative traumadisorders, and what are their symptoms?

Among the more common forms of CTD are DeQuervain’s diseaseand carpal tunnel syndrome, in which the median nerve runningthrough the wrist becomes compressed. Symptoms of carpaltunnel syndrome include pain, numbness, or tingling in the firstthree fingers and the base of the thumb.3 DeQuervain’s diseaseaffects the tendons on the side of the wrist and at the base of thethumb. Symptoms include pain and difficulty in movement.3

Other CTDs include epicondylitis, commonly referred to as “tenniselbow,” which is an inflammation of the tendons within the elbow.Symptoms include swelling, pain, and weakness. Tendinitis is aninflammation of the tendon in the wrist and hand which can causeswelling and pain. “Trigger finger” results when a tendon sheathin the finger swells and becomes locked. The condition is referredto as “trigger finger” because attempts to move the finger resultin a snapping and jerking movement.3

How do I determine my risk of developing a CTD?

"Yes" answers to any of the following indicate that CTD risk factorsare present at your job6:

Are there frequent, repetitive motions?

Does your working position require bending of the neck,shoulder, wrist, or finger joints?

Are there forceful or quick, sudden motions?

Do you work across the midline of your body or out to theside?

What else can I do to relieve some of the discomfort caused byCTDs?

Analgesics, such as acetaminophen or ibuprofen, are often helpful.7

However, as with any health concern, consider seeing your physician,who can accurately assess your condition and recommend anappropriate course of action, which might include physical therapyto help heal strained muscles, and painkillers such as analgesics.

Are there any additional safety considerations, not necessarilymechanical or ergonomic in nature, that I should keep in mindwhen working with pipettes?

Pipetting should never be done by mouth, even if extension tubesare used, in the event that liquids or vapors are drawn into thebody through the mouth or nose.8

Broken glass pipettes can also pose a danger to users. Unusablebroken glassware or pipettes should be collected in a labelledcardboard box which can be sealed for disposal when full.9

&AnswersQuestions

lab report © is published by Artel, Inc. for laboratory professionalsand all pipette users.

For more information, please contact Artel, Inc.

Tel: 207-854-0860 Email: post@artel-usa.com

Fax: 207-854-0867 Web: www.artel-usa.com

25 Bradley Drive, Westbrook, Maine 04092-2013

and swelling.3 An informedtechnician does not have to bea CTD statistic. With CTDs,protection and prevention arethe best medicines.

The solutionsThe design of a pipette is

as important as the manner inwhich it is used. Pipette man-ufacturers recognize thebenefits of an ergonomicallydesigned pipette, and this isrevealed in the designs of pi-pettes on the market. Forexample, pipettes with a curvedhilt allow a relaxed hold, re-ducing muscle strain.

Separate buttons for tipejection, depending upon thetension in the spring within thepipette, usually allow theoperator to use a shorter, lessforceful motion for tip ejectionthan do pipettes with a single“combination” button for bothsample dispensing and tipejection. This can reduce thestress on an operator’s thumb.

A separate ejector, however,requires an additional move-ment to a button which may notbe ergonomically placed. Onelectronic pipettes, the tip ejec-tor is located on the far side ofthe pipette, allowing the user tosimply exert a light squeezewith the index finger in orderto eject the pipette tip. Manualaction pipettes, however, requirethe user to relocate the thumbto another button, further stress-ing the muscles.

Several other features maymake pipetting less stressful.Non slip, contoured surfacesminimize fatigue by increasing

friction, allowing the use of arelaxed grip. Plunger buttonsare sometimes sloped to betterfit the user’s hand. Keep thesefeatures and the list of guide-lines above in mind when pur-chasing and using your pipettes.

Avoiding CTDs is a simpleand relatively inexpensive task,the importance of which cannotbe overestimated. A healthytechnician will have better at-tendance, a better attitude, andbetter accuracy and precisionthan one who is coping withthe effects of CTDs. Pipettingresults are only as reliable asthe mechanism (operator + en-vironment + pipette) withwhich they are obtained. A lab-oratory’s technicians, as wellas its pipettes, should be insound condition, and shouldbe in a comfortable, controlledenvironment.

References:1 Darcor. Ergonomics. The Cost ofCTDs, www.darcor.com.2 Dr. Putz Anderson. FisherScientific, Lab Ergonomics, 1996.3 Lawrence Berkeley Laboratory,PUB 3000, Chapter 17, Ergonomics.4 Fitzgerald, NIH, NIEHS SafetyNotes, April 19965 Kerstin Fredriksson. “LaboratoryWork with Automatic Pipettes: AStudy on How Pipetting Affects theThumb”, Ergonomics 1995, vol 38,no 5, Pharmacia.6 Clark Rundell, Ph.D. Maine MedicalCenter Research Institute, interview.7 University of Utah ResearchFoundation, Ergoweb, 1994-1996.8 Time-Life, Medical ReferenceHandbook, 1996.9 University of Illinois, Lab SafetyExam, 1997. (www.eecs.vic.edu)