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Laboratory Ergonomics

Things you should know...things you should do.

by Other Author

Concern about musculoskeletal disorders (MSDs) has escalated during the last two decades as work cadences, techniques and time pressures have intensified in the life sciences arena.1,2 Extensive pipetting practices, once on the periphery of ergonomics discussions, now form the core of a hot debate because they are considered a major risk factor that could lead to strain-related injuries, especially in biology research laboratories.2-5

Based on an independent evaluation of the activities performed in a typical cellular biology laboratory and conducted by ergonomics consultants, this article reaches beyond the present-day controversy about pipettes and their relationship to the appearance of MSDs and attempts to re-establish the importance of this indispensable tool. Additionally, we propose general recommendations to improve comfort while performing pipette-oriented tasks and reduce the risk of developing MSDs in the laboratory.

Musculoskeletal disorders — Repetitive strain injuries

MSDs are disorders of the osteoarticular and muscular systems involved in movement. Their severity and the physiological regions affected may vary. MSDs result from an imbalance between biomechanical demands and an individual’s functional capacities. Their precise developmental mechanism is not fully known, although some studies have identified contributing factors. Inadequate circulation due to static contractions, highly repetitive work and selective muscular activation over long periods of time are believed to be major factors in the development of muscle, tendon, cartilage and bone lesions. Canadian ergonomists have suggested the name repetitive strain injuries (RSIs) as a subcategory of MSDs attributable to repetitive work.6 Carpal tunnel syndrome (CTS), the most widely recognized RSI, is identified by swelling of the membrane linings and surrounding tendons in the base of the palm. Its symptoms include pain or numbness in the wrist, thumb and first three fingers and loss of strength or dexterity in the hand. Musculoskeletal disorders have multiple origins. Most authorities agree that MSDs result from different factors acting simultaneously, and their severity and individual impact are impossible to foresee. The three main categories of factors associated with the appearance of MSDs are biomechanical, psychosocial and individual (Figure 1).

Figure 1. Contributing Factors to Musculoskeletal Disorders

Ergonomics study in a research laboratory

The ergonomics study sought to determine the relationship between the risk of MSDs and activities involving the use of pipettes and other common tools within a research laboratory specializing in cellular biology. The consultants noted distinct differences in the study participants’ operating modes, primarily because of the high variability of tasks but also because of their individual differences in aptitude, skills and morphology. Lab scientists perform multiple tasks—pipetting, centrifugation, microscopy, calculations, etc.—all of which are governed by time, precision and safety constraints (Figure 2). The study results indicated that 57 to 88 percent of a scientist’s time spent working in the lab involves the use of pipettes. Except for work breaks, which range from 0 to 14 percent of the time worked, the remainder of the scientist’s day, between 9 and 22 percent of the time, is devoted to operations such as centrifugation, microscopy and calculations. The study also reported that intense repetitive movements, ranging from 59 to 89 per minute, were maintained over prolonged periods. Cramped rooms, poorly adapted laboratory furniture (sadly commonplace in laboratories), disorganized workstations and stress resulting from the acoustical assault of droning apparatus all contribute to a greater probability of the appearance of MSDs.

Figure 2. Distribution of Tasks of One Operator (Cell Cloning)

The use of pipettes requires dexterity that is often complicated by tasks that force the operator to adopt awkward postures (Figure 3). For example, manual gel loading demands the technician’s full attention as each sample is transferred into a separate well. Maintaining a reasonable distance can only be theoretical. As with working under the fume hood, one must maintain a nonphysiological alignment of the shoulder, wrist and finger joints.

Accelerations of the heart rate were observed during these tasks, owing to the emotional strain that probably originates with the responsibility for errors and their heavy consequences. Bench work causes difficulties linked with worktable dimensions, which are adapted to neither the sitting nor standing position. The table is either too high for pipetting gestures to be conducted without exaggerated flexion of the shoulder, or too low for techniques that require a short eye-task distance. Other commonly used laboratory apparatuses such as safety screens and microscopes force researchers to assume a boxer’s dodge stance, with arms outstretched in an elevated position for the entire duration of a manipulation. A prolonged static position can generate muscle fatigue in the neck region, leading to pain.

Figure 3. Awkward and Static Postures Lead to Muscle Fatigue

Ergonomics Recommendations

Pipette users acknowledge the transformative effect the RSI debate has imposed on pipette manufacturers, which now develop product plans based on the principles of ergonomics. Pipettes now require less force to operate, and motorized electronic versions drastically reduce hand pain related to prolonged repetitive pipetting. Pipettes aside, there are universal recommendations for improving one’s comfort level in the laboratory7,8 (Table 1). The study revealed that the risk associated with extended use of pipettes depends not only on the ergonomics of the pipettes, other laboratory devices and furniture, but also on factors such as an individual’s physical characteristics, work rhythm, postural constraints and environmental conditions. Choosing the appropriate tools and organizing a work space in a more ergonomic manner can enable one to work smarter and greatly reduce strain-related injuries.

Table 1. General Ergonomics Recommendations

References
1. D. Colombini, A. Grieco, E. Occhipenti, “Occupational musculoskeletal disorders of the upper limbs due to mechanical overload,” Ergonomics, 41(9), 1998.
2. K. Kroemer, “Avoiding cumulative trauma disorders in shops and offices,” Am Indust Hygiene Assoc J, 53(9):599–600, 1992.
3. M.G. Bjorksten, B. Almby, E.S. Jansson, “Hand and shoulder ailments among laboratory technicians using modern plunger-operated pipettes,” Appl Ergon, 25(2):88–94, 1994.
4. G. David, P. Buckle, “A questionnaire survey of the ergonomic problems associated with pipettes and their usage with specific reference to work-related upper limb disorders,” Appl Ergon, 28(4):257–62, 1997.
5. K.R. Asundi, J.M. Bach, D.M. Rempel, “Thumb force and muscle loads are influenced by the design of a mechanical pipette and by pipetting tasks,” Hum Factors, 47(1):67–76, 2005.
6. Presentation, Annual Conference of the Association of Canadian Ergonomists 2003.
7. European and ISO standards (Table 1).
8. International Encyclopedia of Ergonomics and Human Factors, 2001, Taylor & Francis eds.