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BioPerspectives

Liquid Handling Best Practices

Ergonomics factors more into lab safety and performance than you may realize.
  • Sandra Doehr
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  • Carolyn Phelan
  • ,
  • Mickie Henshall

For Laboratory Technicians, the Risk is Real

Identified as Repetitive Stress Injuries (RSI), musculoskeletal injuries in the workplace have been a serious issue for the past decade, amounting to tens of billions of dollars in costs associated with diagnosis and treatment. In a news release summarizing 2011 statistics, the U.S. Department of Labor (DOL), Bureau of Labor Statistics (BLS) reported 387,820 cases of ergonomically related injuries, which represented 33% of all cases of workplace injuries and illnesses reported1. Furthermore, over 40,000 cases were directly related to hand, wrist, finger and arm RSIs2.

For laboratory technicians, the repetitive nature of standard laboratory techniques, especially pipetting, makes the risk of RSI quite real. In a study published by Bjorksten et al., manual pipetting for more than 300 hours per year increases the risk of hand and shoulder injuries3. When put in perspective, full-time laboratory technicians who pipette just three hours or more per day will exceed the risk factor described in the study.

Common RSDs in the Laboratory

There are three common areas of injury in the laboratory: Shoulder injuries, elbow injuries, and hand injuries. Shoulder injuries usually fall into Impingement Syndrome or Muscle/Neck Fatigue, both of which can be caused by pinching of the rotator cuff and neck muscles when using a “winged” pipetting technique.

Elbow injuries include Lateral Epicondylitis (Tennis Elbow) and Cubital Tunnel Syndrome caused by prolonged pressure on a hard surface or awkward positioning of arms and elbows in the hood.

Hand injuries can occur such as Carpal Tunnel Syndrome, Tenosynovitis with Trigger Thumb/Finger and De Quervain Tenosynovitis caused by force, repetition, pinching and twisting, excessive force in mounting and ejecting tips, repetitive twisting motions for opening tube caps, and one-handed manipulation of PCR tubes and strips.

Safety and Ergonomics

It is important to report any injuries or symptoms to your health care provider or lab safety officer. In addition, follow these best practices for optimum safety and performance while pipetting:

Establish a Bench Top Comfort Zone

Place the most-used equipment and materials within easy reach, no more than 15 inches away and adjust your chair to an appropriate height to prevent leaning or excessive arm raise. Minimize reaching by placing items that are used less often, like stock reagents and consumables, to within 24” of your reach.

When sitting, ensure that you have leg room with your legs positioned at a 90 ° angle with your back supported. Be sure to avoid any twisting or leaning.

Relaxed Posture

Keep shoulders relaxed and elbows close to your sides when working. Maintain a neutral or aligned wrist and arm posture when working. Avoid forceful twisting and turning motions and work with the wrist in a neutral or straight position (“hand-shake” position).

Pipetting Technique

At all times, avoid a “winged” pipetting technique. Using an upper arm angle of 30° is ideal (where the arm is closer to the side of the body); this lends 100% arm strength to the job and lowers the risk of shoulder strain. When your arm is angled at 90° (nearly at shoulder level) arm strength is reduced to 83% and at 150° (above shoulder level) your strength is reduced to 60% which makes you more susceptible to injury.

Use light pressure when pipetting and be aware of the force you are using to mount and eject pipette tips. Tips engineered for the lightest insertion and ejection forces are the best type for overall reduced muscle work. Use lightweight, ergonomically-designed pipette models whenever possible.

Use Ergonomic Tools for Pipetting

If you must rest your elbow on a surface while working, use an elbow pad. An arm sleeve with elbow pad may be worn for support. If standing, stand on an anti-fatigue floor mat. Use ergonomic tools such as tube-cap openers to lessen strain on the thumbs.

Hand Exercises and Upper Quadrant Stretches

Stretching exercises are always a best practice for preventing RSI injury. Even as little as 20 seconds of stretching after 20 minutes of continuous pipetting can have a positive impact. Using the hand exercises and stretches that can be found at www.rsitips.com/rsi-prevention-exercises will keep your muscles flexible, release strain and prime your hands, wrists and shoulders for more comfortable liquid handling.

Ergonomic safety and best practices, when combined with proper pipetting technique and tools, will contribute to accuracy, precision, safety and comfort while performing pipetting in the lab. Refer to the article “Liquid Handling Tips” for further discussion of proper pipetting technique. Also, be sure to check out the infographic "For Laboratory Technicians, the Risk is Real".