Case Study 1:
– Basic Biosafety (includes animals)
Safe Sharp Devices
Content Author
Benjamin Fontes, MPH, CBSP
Yale University
Introduction
There are likely more engineering controls related to sharp instruments (such as
needles and syringes, scalpels, and glass equipment) than other devices. The passage
of the Occupational Safety and Health Administration (OSHA) Bloodborne Pathogens
Standard to minimize exposure to Human Immunodeficiency virus (HIV), Hepatitis B
virus (HBV), and Hepatitis C virus (HCV), led to an increase in the development of safe
sharps devices to protect workers.
The implementation of the Needlestick Safety and Prevention Act of 2000 required
employers to consider safe sharps devices and other engineering controls as part of
their safety program, and also in the aftermath of an exposure involving a sharp
contaminated with human material.
Learning Objectives
By the end of this module, you should be able to:
Identify various types of safety needles and other safe sharps devices.
Identify various ways of managing scalpels and other reusable sharps.
Selection of Safe Sharps Devices
Employees must be involved in the selection of the safe sharps devices and have an
opportunity to evaluate them in practice conditions that do not involve potential
exposure. If it is deemed that a safe sharps device will likely minimize the potential for
exposure or that it could have prevented an actual exposure if it were used, the device
must be offered to employees as a protective measure.
Needles, Needles with Sliding Shields, and Disposable Scalpels
The images below show a few safe sharps, including needles, needles with various
sliding shields, and disposable scalpels with sliding shields. The images show the safe
sharps before engagement and after engagement.
Needle Before Engagement
Needle After Engagement
Needles with Sliding Shield Before Engagement
Needles with Sliding Shield After Engagement
Disposable Scalpel with Sliding Shield Before Engagement
Disposable Scalpel with Sliding Shield After Engagement
Retractable Needles
The images below show a retractable needle before and after engagement. A
retractable needle will release the needle back into the syringe after pressing down on
the end of the syringe after the inoculation. The activation of the retractable needle
causes the needle to move backwards into the syringe, making it safer for disposal.
Retractable Needle Before Engagement
Retractable Needle After Engagement
Discarding Safe Sharps
Despite advances in the technology involving safe sharps, there is no replacement for
placing a sharps disposal container or needle box in the immediate vicinity of use, and
discarding used needles, syringes, and other sharps immediately after use. Some
researchers believe that needles should be recapped immediately after use to protect
themselves and others. This is a dangerous practice and should not be performed
unless approved by the safety office prior to initiation. The image below shows a needle
box or sharps container located in the immediate vicinity of use (in this case inside a
biosafety cabinet). Placing the sharps container in this location makes it very easy to
discard the sharp immediately after use.
Never allow needle boxes or sharps containers to overfill; replace them when two-thirds
to three-quarters full. Needle boxes or sharps containers must also be rigid on the sides
and bottom, and leak proof.
Scalpels
Scalpels are dangerous devices that can injure and expose researchers during use, as
well as afterwards during the removal and change out of the scalpel blade. Removal of
a used or contaminated blade should never be done directly by hand, as this could lead
to direct introduction of the contaminant through the skin. Special devices have been
developed to remove the blade in a way that does not involve the hand. The image
below shows a scalpel removal device.
Scalpels can also be removed from the blade with the use of a forceps, hemostat, or
kelly clamp. If they must be removed, needles can also be removed from a syringe with
similar engineering controls. In both cases, the goal is to keep the researcher's hands
away from the contaminated sharp. Again, this is no substitute for placing the needle
and syringe directly into the sharps container. However, in cases where the contents of
the syringe must be filtered, this is a safe way to remove the needle from the syringe.
Reusable Sharps
Reusable sharps require care prior to reprocessing and decontamination. Reusable
sharps (such as scissors and fine tipped scissors) must be handled safely prior to
transfer to technicians for sterilizing. The researcher can easily accomplish this by
placing reusable sharps directly into a labeled, unbreakable, and leak proof container
that contains an appropriate disinfectant immediately after use as shown in the image
below.
If possible, as shown in the image above, place the sharp instruments within the
container so that the sharps’ ends are all facing in the same direction. Use another
engineering control, such as a set of tongs, to remove reusable sharps from the
disinfectant soak container. Examine the reusable sharps for any contamination (such
as dried blood) or areas under which the disinfectant may not have contacted. Use a
brush or tongs with paper towels held between the tong ends (as shown in the image
below) to clean any visible blood or other contamination from the reusable sharp and
then place it back into the container to complete the disinfection.
Glass and Plastic Pipettes
When biohazards are manipulated, glass should be replaced with plastic (if possible).
Plastic pipettes, especially plastic aspiration pipettes, are preferred in cell culture
laboratories handling biohazards to eliminate the potential for a puncture by
contaminated glass. Glass and plastic pipettes contaminated with a biohazard must be
handled as biomedical waste and appropriately decontaminated. As these items
frequently puncture bags, they are normally collected in a rigid puncture resistant, leak
proof container for safe handling and protection of the individuals who handle the waste
for the laboratory. The image below shows a rigid biomedical waste container suitable
for the collection of plastic pipettes and pipette tips. This container contains a
disinfectant solution to begin treating the lab waste promptly after use. Cardboard boxes
lined with bags may also be suitable for the collection of this waste, but first must be
evaluated.
Needlestick
A researcher notified the occupational health clinic regarding a needlestick
exposure to primary human cells that were being inoculated into a research
mouse. The researcher had just inoculated the mouse when he noticed
additional bleeding coming from the site of injection. Therefore, he dropped
the needle on the work surface and grabbed paper towels to stop the
mouse’s bleeding.
After doing so, the researcher picked up the needle from the work surface
to discard it into the sharps container. He realized that the needle was not
going to get into the top of the needle box the way it was held in his hand,
so he re-positioned the needle to get a better grip and was stuck while
moving the needle. He placed the needle into the sharps container after he
was stuck, washed the wound, and reported to occupational health.
Review recommendations for this worker and his lab group.
o Consider the use of a retractable needle and syringe. This
would have allowed the researcher to press the syringe all the
way, moving the needle inside the syringe hub to protect from
the stick.
o Position the sharps container closer to the work area. This
would likely have allowed an easier transfer into the container
after use.
o Use a set of tongs or forceps to pick up the needle from the
work surface in this situation and discard it into the needle box
with an engineering control.
Close
Summary
This module reviewed a variety of safe sharps devices and examined how they may be
used in the work place to minimize exposure to bloodborne pathogens. It also
emphasized the role of the end user in evaluating safe sharps prior to implementing
them into use.
Reference
Needlestick Safety and Prevention Act, Pub. L. 106-430 (2000).
Original Release: February 2010
Last Updated: January 2019
Case Study 2:
Centrifuge Precautions
Texas State University – Basic Biosafety (includes animals)
Centrifuge Precautions
Content Author
Benjamin Fontes, MPH, CBSP
Yale University
Introduction
Laboratory equipment can be associated with the generation of aerosols and workers
must be aware of equipment containment practices. Centrifuges are associated with a
high potential risk of aerosol generation, due to the high speeds and pressures involved.
At a minimum, centrifuges should be equipped with a solid cover and have a safety
interlock that prevents opening until the centrifuge has come to a complete stop. These
two features are required for biohazard research per the Occupational Safety and
Health Administration (OSHA) Bloodborne Pathogens Standard. Many centrifuge
manufacturers have designed aerosol containment into their equipment, such as
aerosol canisters, safety buckets, sealed tube systems, and sealed rotors. This
secondary containment barrier provides a safety net in the event of a leak of the primary
tube during the centrifuge run.
Learning Objectives
By the end of this module, you should be able to:
Describe best practices associated with the use, inspection, and decontamination
of centrifuge equipment.
Recognize secondary containment equipment for the centrifugation of
biohazards.
Work Practices
Researchers must be trained in the use, inspection, and decontamination of secondary
containment devices. Centrifuge work practices are described in detail below.
Each centrifuge operator should be trained on the proper operating procedures.
Keep a logbook detailing operation records for centrifuges and rotors.
Do not exceed safe rotor speed.
Place a biohazard label on the centrifuge if used for biohazards. The image
below shows a centrifuge posted with emergency response and safe use
instructions.
Use secondary containment devices when centrifuging biohazards and
decontaminate them before removing from the cabinet and also after use. The
images below show two different types of sealed safety buckets before use.
Check safety buckets and rotors for appropriate gaskets or deformities before
use. The blue arrow in the image below shows where the rubber gasket is, which
provides the aerosol seal to prevent the release of liquids or aerosols during the
run in the event of a release. If deformities are identified, the safety bucket
should not be used until the damaged gasket has been replaced.
Always use sealed primary tubes. Avoid the use of open tubes, or snap cap
tubes for microfuges, which do not provide a positive seal.
Do not overfill primary containers; do not exceed 75 percent (or ¾) full.
Balance loads to avoid damage to centrifuge. The image below shows a
researcher balancing the centrifuge prior to the run. Laboratories will keep
balance tubes near the centrifuge to balance internal loads within the sealed
safety buckets.
Load and unload safety buckets or sealed rotors inside the biological safety
cabinet. The image below shows a researcher loading a tube inside a centrifuge
rack that will be placed inside an aerosol containment safety bucket.
Wipe the exterior of tubes or bottles with disinfectant prior to loading into safety
buckets or rotor.
Wipe the exterior of safety buckets or rotors with disinfectant before removing
from biosafety cabinet. The image below shows a researcher spraying the
exterior of the safety bucket with disinfectant. Once the entire safety bucket has
been decontaminated for the appropriate contact time, the researcher can
change or disinfect their gloves and then move the safety bucket to the
centrifuge.
Stop the centrifuge immediately if an unusual condition, such as noise or
vibration begins.
After the run, wait three to five minutes before opening the centrifuge and moving
the safety buckets or rotors to the biosafety cabinet to allow any aerosols to
settle.
Decontaminate safety buckets or rotors and centrifuge interior after each use.
Shortcut to Sickbay After Failing to Confine
Aerosols
Summary
A researcher was hospitalized and diagnosed with an infection with a high-
risk agent that he had been handling in his laboratory. Although the
researcher could not recall a direct exposure event, he did share details
regarding a spill in the centrifuge about a week earlier. He informed the
emergency room physicians that he was not exposed during the spill. He
was opening the sealed leak-proof rotor after the run inside the centrifuge
and noticed liquid inside the rotor and one empty bottle that contained
infectious virus. Recognizing that virus had been released from the bottle,
the researcher immediately put on a surgical mask and a second pair of
gloves to clean up the spill. He prepared a 10 percent bleach solution and
began pouring this inside the centrifuge to decontaminate the spill. As he
was able to clean up the spill very quickly, he did not alert his principal
investigator, the biosafety office, or employee health. He began
experiencing symptoms of viral infection about three days later, and by the
seventh day, his condition deteriorated where he needed to be brought to
the emergency room for immediate medical attention.
Lessons
The researcher took quite a few shortcuts in this laboratory associated
infection involving a release of virus from a centrifuge tube.
The researcher opened the sealed rotor outside of the biological
safety cabinet. Sealed centrifuge rotors are used to contain
biological aerosols in the event of a leak from the primary
containment tube during the centrifuge run. When working with high-
risk pathogens, this sealed rotor must be opened inside a biological
safety cabinet. In this case, in the event of a leak, aerosols would be
contained.
The researcher did not immediately evacuate the laboratory at the
time of the biohazard spill. All researchers must evacuate the
laboratory following a spill or release of human pathogens and allow
sufficient time for aerosols to settle or be removed by the laboratory
ventilation system. Spills and releases of biohazards from high
speed equipment have the potential to generate a significant number
of infectious bioaerosols.
The researcher wore a surgical mask to protect himself during the
spill cleanup. A surgical mask does not create a tight seal on the
worker’s face. Because air travels along a path of least resistance,
infectious bioaerosols can get through the gaps around the mask
and into the worker’s breathing zone.
The researcher immediately poured disinfectant directly on the
spilled material inside the centrifuge. Avoid pouring a liquid directly
onto another liquid. This can also create aerosols. Covering spills
with paper towels and pouring disinfectant around the perimeter of
the towels and into the spill avoids the creation of aerosols.
The researcher never reported the spill to his principal investigator,
the biosafety office, or employee health. The researcher never had a
chance to review procedures in the aftermath of the spill to check for
biocontainment breaches. The biosafety office never had an
opportunity to review the incident, spill cleanup, or the need for
additional decontamination. The health office never had an
opportunity to review potential exposures, provide post-exposure
prophylaxis, and alert the researcher of signs and symptoms of
infection to watch for.
Close
Summary
This module focused on the safe centrifugation of biohazards. A review of containment
equipment, work practices, decontamination recommendations, and aerosol
containment was provided.
Additional Resource
Occupational Safety and Health Administration (OSHA). 2011. “OSHA Quick
Facts: Laboratory Safety Centrifuges.” Accessed December 20, 2018.
Original Release: February 2010
Last Updated: January 2019