With fast centrifuges, such as high-speed and ultracentrifuges, scientists must be even more careful in using these devices. For a reminder, do an online search for “centrifuge accident” and take a few minutes looking at the images. Most of the photos show a failed rotor—one spun into pieces—but it can get even worse, completely destroying a centrifuge, which risks the lives of people in a lab. Here’s how to keep a lab team safe.
Before addressing the dangers, scientists must know the potential problems. According to Melissa Brower, spokesperson for the Center for Surveillance, Epidemiology, and Laboratory Services at the U.S. Centers for Disease Control and Prevention (CDC): “Centrifuges can be extremely dangerous instruments if not properly cleaned, maintained and operated.” She added, “Laboratory staff must be trained in centrifuge operation and the hazards and consequences associated with centrifugation such as: lifting heavy rotors can cause bodily harm; a centrifuge not properly grounded can cause electrical shock; using corroded, cracked, dented or not balanced rotors can cause explosions; and constant exposure to excessive noise can cause hearing loss.”
Rules of the Rotor
The moving parts in a centrifuge can pose the biggest dangers, and that focuses attention on the rotor. “The first key safety consideration is balancing the rotor, and this includes two parts: sample balancing and position balancing,” said Jiefu Yin, laboratory manager at the Cornell Energy Systems Institute. “Sample balancing requires the mass difference between tubes to be as low as possible, and position balancing requires that the centrifuge tubes need to be placed symmetrically in the rotor.”
The built-in safety components of today’s smart centrifuges can help a scientist reduce their risk in the lab. As Yin noted, for example, “Most of the modern ultracentrifuges have an imbalance detector that can turn the centrifuge off before any eccentric rotation caused by a load imbalance, however, the shaft may still be damaged in the initial stage.” So, scientists still need to be careful to balance a centrifuge load.
In addition to the rotor, the sample tubes must be filled properly. “Typically, the centrifuge tube has an indication line, and people should fill the tube to that line—no more or less,” Yin said.
Beyond paying attention to a tube’s fill line, centrifuge users must read a platform’s directions. “Manufacturer instructions for use and care of centrifuges, and especially rotors, are to be strictly enforced to prevent the serious hazards and potential exposures associated with rotor failure,” said Brower. “Site- and activity-specific biosafety risk assessments should be performed to determine if additional biosafety precautions are warranted based on situational needs.” Safety depends on more than the centrifuge itself, what goes inside matters.
Sample-Based Safety
When spinning samples, a scientist wants that material to stay in the tube, but that does not always happen. “Tube breakage during centrifugation presents the greatest risk for contamination, because large aerosol clouds are produced,” Brower explained. “Consistent use of gasketed centrifuge safety cups and sealed rotors can substantially reduce the risks associated with centrifuging infectious or potentially infectious materials.”
Yin mentioned that dangerous samples can include toxic inorganic or organic materials, as well as biohazards, such as a human pathogen. “To run these samples safely, people should wear proper PPE—personal protective equipment—when loading the samples to the tube and rotor,” he said. “If contamination is observed, people should follow the proper procedure to clean or inactivate it and call environmental health and safety if the contamination cannot be handled.”
Scientists can take additional steps to keep lab personnel safe when anyone is centrifuging samples that could create infectious aerosols. “To prevent aerosol exposure, centrifuge viable infectious organisms in sealed buckets or rotors,” Brower said. “Load and unload the buckets or rotors only in a biological safety cabinet.”
Take Training
Many scientists, including me, learned to use a centrifuge based on a few instructions from someone leading a lab. That training really varies, which means that something more formal could be warranted. Plus, the technology changes over time. So, it’s worth taking some training, even if it’s just to refresh or update knowledge about using a high-speed centrifuge. “Laboratory professionals can find free online courses with P.A.C.E. credits to learn the Fundamentals Of Centrifuge Safety and the Fundamentals of Working Safely in a Biological Safety Cabinet,” Brower said.
The ongoing pandemic creates additional dangers that some scientist face when processing COVID-19 specimens. To help keep these scientists safe, the CDC developed: Interim Laboratory Biosafety Guidelines for Handling and Processing Specimens Associated with Coronavirus Disease 2019.
During a pandemic or not, scientists should keep in mind the dangers of centrifuging. Then, using the right equipment and providing useful training—and following it—reduces the odds of a centrifuge-based accident in a lab.