Pipetting is a necessary but often monotonous laboratory task that many scientists perform for hours each day. Manual pipetting is often described as time-consuming, repetitive or dull, but it can also be a health risk, especially for those who perform the task for hundreds of hours a year throughout their career. Repetitive strain injuries (RSI), an umbrella term that can include conditions such as carpal tunnel syndrome, cubital tunnel syndrome and tendinosis, are musculoskeletal or nerve injuries resulting from a gradual buildup of damage due to repeated motions – like pipetting. Symptoms of RSI include pain, stiffness, weakness or numbness in the affected areas; for pipette users, this could be felt in the thumb, hand or wrist, and even extend to the elbow, neck, shoulders or back after long periods spent sitting in the same position. In extreme cases, RSI can affect the use of one’s hands or limbs so severely that they can no longer perform necessary work tasks.
When it comes to lab safety, many scientists are understandably more worried about serious accidents such as chemical spills or fires, but the potential impact of RSI should not be overlooked. According to the U.S. Bureau of Labor Statistics (BLS), in 2018, about 30% of workplace injuries resulting in days away from work were musculoskeletal disorders (MSDs), with repetitive motion being one of the primary causes.1 In 2000, the U.S. Occupational Safety and Health Administration (OSHA) estimated the direct costs of work-related MSDs to be between $15-20 billion per year.2 And while RSIs are often associated with working long hours at a computer or on an assembly line, lab workers are also at risk due to the force and repetition associated with manual pipetting. For example, one survey-based study found that pipette users reported significantly higher rates of hand and elbow problems than non-users, and that almost 90% of workers who use pipettes continuously for more than an hour at a time reported pain or discomfort in their hands.3
With all of this in mind, how can one minimize strain when performing these necessary liquid handling tasks? Fortunately, there are many steps both workers and laboratories can take to embrace ergonomics, reduce the risk of RSIs and make pipetting safer and more comfortable.
1. Create a Comfortable Workspace
Setting up an appropriate workspace is key to getting your pipetting session off to the right start. Being mindful of your work environment can set you up to both work in a comfortable position and reduce unnecessary motions that can cause strain over time. One aspect individual pipette users have the most control over is the positioning of items on the workbench, such as tubes, well plates, reagents, tips and disposal containers. The items that will be most frequently accessed should be placed close to the edge of the bench and organized in a manner that reduces unnecessary reaching, leaning or extension of the arm and wrist. Less frequently used items, such as a pipette stand or vortex, can be placed further away but ideally still within arm’s reach.
The bench and chair used for pipetting tasks can make a big difference in allowing for a healthy posture that reduces strain in the neck, shoulders, elbows and back. Pipetting tasks should ideally be performed at a bench with cut-out space beneath so the user can be seated as close to the bench as possible. Height adjustable lab chairs are also preferred so that any user can adjust to a height where they can work comfortably at the bench. For example, if the height of the chair is too high, the user may have to crane their neck down further to look at the workspace, which can cause significant strain over time. Chairs with backrests and footrests (or separate footrests placed in front of the chair) provide additional support and reduce strain on the back and legs when seated for long periods of time. Additional suggestions for making the workspace more ergonomic are using an elbow rest to reduce hard contact of the elbow against the benchtop, and using a short waste container, or waste container tilted toward the user, to reduce lifting and extension of the arm when disposing pipette tips.
2. Pay Attention to Posture and Pipetting Technique
Proper posture and pipetting technique are key to cutting out unnecessary strain during long pipetting sessions. Small adjustments to the way you sit and move can make a big difference in the long run. As mentioned, one should sit close to the workbench to reduce the need to reach and lean – this is especially important when working in biological safety cabinets, where tools must be positioned closer to the center of the cabinet. The height of the chair should ideally be adjusted so the benchtop is at or just below the height of the elbow. For improved leg circulation, placing one’s feet on the floor or on a footrest – with their knees bent at a 90 degree angle – is preferable to the use of “ring-type” footrests found on many lab chairs, where the feet are tucked more inward.
While it is obviously necessary to look down at what you’re doing when pipetting, one should avoid lowering their head more than necessary, to avoid straining the neck; the back should be kept straight, the shoulders should be relaxed and the forearms should be at about a 90 degree angle to the body. When pipetting, users should avoid bending their wrist and instead keep their wrist aligned with their forearm at all times. Users should also avoid gripping the pipette more tightly than necessary, and only exert the minimum amount of force needed for aspiration, dispensing, tip disposal and volume adjustment etc.
3. Take Breaks
Some pipetting sessions can go on for hours, and extended periods of non-stop repetition can take a huge toll on your thumb, hand and arm. For long sessions, it’s important to take periodic breaks to give your muscles a little time to rest and recover. OSHA recommends that pipette users take a 1- to 2-minute break for every 20 minutes of pipetting.4 Use these breaks as an opportunity to stretch or stand up and walk for a bit. If you are able to, alternate the hand you use for pipetting between breaks to give your other hand an even longer rest.
4. Select Pipettes with Ergonomic Features
The risk of developing an RSI increases with a greater number of repetitions and with higher levels of force. Many modern pipettes come with ergonomic features designed to reduce one or more of these factors, something that should always be considered when shopping for new pipettes. Firstly, the size of the pipette/handle should be considered – if the pipette is too large or small to hold comfortably, the force needed to grip it can be enough to strain the hand. Look for models with hook-like finger rests, which also allow the pipette to be held with less force. Some pipettes are specifically designed to minimize the force needed for each step of the pipetting process, with electronic pipettes needing the least force, only requiring the light push of a button for each task. Another important consideration is the ease of mounting new tips onto the device – motions such as twisting, rocking or slamming in an attempt to get a good seal can exert a lot of force that will build up damage in the hand and wrist over time. Ensuring the use of tips that fit that well and mount easily can save users both time and hand strain in the long run.
Another pipette design feature you may want to look for is the ability to use the thumb for dispensing and the index finger for aspiration – alternating between the two fingers reduces repetitive motions of the thumb. Multichannel pipettes are another option that not only increase productivity, but also reduce the number of repetitions needed to fill large well plates.
5. Consider Automated Pipetting
While not the cheapest option for reducing pipetting strain, liquid handling robots offer numerous benefits in addition to reducing the physical burden or manual pipetting. In addition, liquid handling robots come in different sizes and with levels of automation, and more budget-friendly options can still reduce, if not eliminate, pipetting hours. With increased throughput and precision, and more time for scientists to focus on other tasks, automated liquid handling should be considered by any lab where pipetting is a chore.
References
- "Occupational injuries and illnesses resulting in musculoskeletal disorders (MSDs)," Factsheet, U.S. Bureau of Labor Statistics (2020). https://www.bls.gov/iif/factsheets/msds.htm
- "Statement of Charles N. Jeffress, Assistant Secretary for Occupational Safety and Health, U.S. Department of Labor, before the Subcommittee on Employment, Safety, and Training of the Senate Health, Education, Labor and Pensions Committee," OSHA Archive. https://www.osha.gov/news/testimonies/04272000
- David, G.; Buckle, P. A Questionnaire Survey of the Ergonomie Problems Associated with Pipettes and Their Usage with Specific Reference to Work-Related Upper Limb Disorders. Applied Ergonomics 1997, 28 (4), 257–262. https://doi.org/10.1016/s0003-6870(97)00002-1.
- "Laboratory Safety Ergonomics for the Prevention of Musculoskeletal Disorders," Factsheet, OSHA (2011). https://www.osha.gov/sites/default/files/publications/OSHAfactsheet-laboratory-safety-ergonomics.pdf