Credit: Thermo Fisher Scientific
by David Philips, PhD, Senior Global Product Technology Specialist, BSCs and Clean Air, Thermo Fisher Scientific
Laboratorians working in life science and elsewhere are at risk from ergonomic threats in addition to the biological, chemical, and physical risks from their work. El-Helaly, Balkhy, and Vallenius (2017) found that almost 10% of laboratory technicians had carpal tunnel syndrome (CTS). Those with CTS tended to have been working in the laboratory longer. Gül and Gül (2018) found that 62% of health personnel working in tuberculosis laboratories had shoulder pain, 25% had hand and wrist pain, and 19% had elbow pain.
The potential threats from weak ergonomic design increase when a laboratory transitions from academic research done in addition to teaching or taking classes to intense ongoing efforts and commercial production. Not all devices in laboratories are used equally. Laboratories benefit by identifying frequent and high-use devices and activities where ergonomic design can have the greatest effect.
Biological safety cabinets (BSCs) are laboratory workstations where ergonomic considerations are particularly helpful. Unlike working at a bench, the BSC requires the operator to work through a fixed opening that is eight to ten inches tall. This restrictive fixed opening limits the positions the operator can take and their ability to reduce ergonomic stress with minor changes to their position as they work.
In a study at a North American university, the average non-zero use of a BSC was 17.6 hours per week, with 43% of the BSCs surveyed being used less than 10 hours per week (Phillips, 2015). The ergonomic impact of a BSC or other device used less than 10 hours per week is much less than that of one used throughout the majority of the workday. A key task is to identify high-use devices in the laboratory and optimize their ergonomics.
BSCs and CO2 incubators are often used in tandem with samples moving from the incubator to the BSC for processing and then back to the incubator. The location of incubators relative to the BSC can vary. The height of the incubators varies, too, as some are stacked. The placement of the door handle and direction of the door opening can all affect the ergonomic demand on the laboratorian, depending on the frequency of access.
Because the incubator height and the user height can both vary, a full-length outer door handle accommodates users of different heights while allowing the proper angle to open the incubator without causing rocking that could disturb cell cultures. Also, a touchscreen display near the door handle that is positioned vertically makes viewing and changing parameters more accessible for different users.
Ergonomic demands at the BSC itself tend to fall into two categories: work environment and operator position. The work environment comes into play once the laboratorian is positioned at the cabinet and includes the lighting, noise and vibration inside the cabinet sample chamber. Cabinets that have been independently validated to recognized global BSC standards like NSF/ANSI 49 and EN 12469 tend to provide similar environments. The work environment inside non-validated cabinets may vary and should be reviewed.
The most challenging ergonomic aspect for most BSC users is the operator position. We can adapt guidelines for the BSC from OSHA’s guidance for good working positions at computer workstations. While some cabinets are equipped with electrically adjustable stands, the positions of most cabinets are fixed at installation. These guidelines assume the cabinet position is fixed.
- Start with your forearms parallel to the floor with hands reaching into the BSC work area. Your elbows are close to the body and angled between 90 and 120 degrees. The cabinet work opening and height are our anchors, and we are positioning our body to work ergonomically within this fixed location.
- While maintaining the position of your hands and elbows, position and adjust the height of your seat to support a vertical position for your torso, including support for your back.
- While maintaining the positions of your hands, elbows and torso, your thighs should be parallel to the floor. Usually, however, they are slightly declined to fit under the BSC, so the angle between the torso and thighs is greater than 90 degrees.
- Your feet are fully supported by the floor or footrest, with the feet slightly forward of the knees.
These steps use three positional tools available to most BSC operators. There is the stand itself. In addition to electric stands, stands can be fixed height or adjustable at installation. Cabinets tend to place the work surface around 28 to 32 inches above the floor. Mechanically adjustable stands for BSCs have heights that are selectable at installation. The available ranges tend to be from 28 to as high as 38 inches above the floor. The greater heights tend to be for applications where the user will work in the cabinet while standing.
After the BSC stand, we need to look at the stool or chair for the BSC user. These are typical laboratory stools or chairs. For use with a BSC, consider whether armrests on the chair might impede positions close to the cabinet. Sometimes stools are preferred in containment laboratories where users wear powered respirators with hoses going to the users’ backs. The key element for both the chairs and footrests is adjustability.
Laboratory ergonomics is sometimes not given appropriate consideration. Perhaps this is because for many people, their laboratory experience was for short intervals at the beginning of their careers. However, as significant progress and advances contributing to healthcare come out of life science and other laboratories, people are spending more time at the bench. What was an occasional requirement has become a daily demand and the ergonomic stress on laboratories has been shown to be significant and harmful. When BSCs and incubators are significant ergonomic elements in the workflow, planning and execution of proper positioning is critical.
About the author
David Phillips has been involved with biological safety cabinets (BSCs) for over 40 years. He was a BSC field certifier up until 2007, when he joined Thermo Fisher Scientific’s BSC product team. He is on the NSF Joint Committee for NSF/ANSI 49 and has been an NSF Accredited BSC Field Certifier under the Enhanced program for over 24 years. He has a doctorate in management from the University of Maryland. His key areas of interest are improving BSC sustainability and effective access to BSCs globally.