11,Safety equipment
As aerosols are important sources of infection,care should
be taken to reduce the extent of their formation and
dispersion,Hazardous aerosols can be generated by many
laboratory operations,e.g,blending,mixing,grinding,
shaking,stirring,sonicating and centrifuging of infectious
materials,Even when safe equipment is used,it is best to
carry out these operations in an approved biological safety
cabinet whenever possible.
Biological safety cabinets and their use and testing are
discussed in Chapter 10,The use of safety equipment is no
assurance of protection unless the operator is trained and
uses proper techniques,Equipment should be tested
regularly to ensure its continued safe performance.
Table 10 provides a checklist of safety equipment designed
to eliminate or reduce certain hazards and briefly outlines
the safety features,
Negative-pressure flexible-film isolators
The negative-pressure flexible-film isolator is a self-
contained primary containment device that provides
maximum protection against hazardous biological
materials,It may be mounted on a mobile stand,The
workspace is totally enclosed in a transparent
polyvinylchloride (PVC) envelope suspended from a steel
framework,
The isolator is maintained at an internal pressure lower
than atmospheric pressure,Inlet air is passed through one
HEPA filter and outlet air is passed through two HEPA
filters,thus obviating the need to duct exhaust air outside
the building,The isolator may be fitted with an incubator,
microscope and other laboratory equipment,such as
centrifuges,animal cages,heat blocks,etc,
Material is introduced and removed from the isolator
through supply and sample ports without compromising
microbiological security,Manipulations are performed
using gloved sleeves incorporating disposable gloves,A
manometer is installed to monitor envelope pressure.
Flexible-film isolators are used to manipulate high-risk
organisms (Risk Groups 3 or 4) in field work where it is
not feasible or appropriate to install or maintain
conventional biological safety cabinets.
Pipetting aids
A pipetting aid must always be used for pipetting
procedures,Mouth pipetting must be strictly forbidden.
The importance of pipetting aids cannot be
overemphasized,The most common hazards associated
with pipetting procedures are the result of mouth suction,
Oral aspiration and ingestion of hazardous materials have
been responsible for many laboratory-associated infections.
Pathogens can also be transferred to the mouth if a
contaminated finger is placed on the suction end of a
pipette,A lesser known hazard of mouth pipetting is the
inhalation of aerosols caused by suction,
The cotton plug is not an efficient microbial filter at
negative or positive pressure,and particles may be sucked
through it,Violent suction may be applied when the plug is
tightly packed,resulting in the aspiration of plug,aerosol
and even liquid,The ingestion of pathogens is prevented
by the use of pipetting aids.
Aerosols can also be generated when a liquid is dropped
from a pipette on to a work surface,when cultures are
mixed by alternate sucking and blowing,and when the last
drop is blown out of a pipette,
The inhalation of aerosols unavoidably generated during
pipetting operations can be prevented by working in a
biological safety cabinet,
Pipetting aids should be selected with care,Their design
and use should not create an additional infectious hazard
and they should be easy to sterilize and clean,Plugged
(aerosol-resistant) pipette tips should be used when
manipulating microorganisms and cell cultures.
Pipettes with cracked or chipped suction ends should not
be used as they damage the seating seals of pipetting aids
and so create a hazard.
Homogenizers,shakers,blenders and sonicators
Domestic (kitchen) homogenizers are not sealed and
release aerosols,Only equipment designed for laboratory
use should be used,
Their construction minimizes or prevents such release,
Stomachers,which are now available for use with large
and small volumes,may also produce aerosols.
Homogenizers used for Risk Group 3 microorganisms
should always be loaded and reopened in biological safety
cabinets.
Sonicators may release aerosols,They should be operated
in biological safety cabinets or covered with shields during
use,The shields and outsides of sonicators should be
decontaminated after use.
Disposable transfer loops
The advantage of disposable transfer loops is that they do
not have to be sterilized and can therefore be used in
biological safety cabinets where Bunsen burners and
microincinerators would disturb the airflow,These loops
should be placed in disinfectant after use and discarded as
contaminated waste
Microincinerators
Gas- and electrically-heated microincinerators have
borosilicate glass or ceramic shields that minimize the
spatter and dispersal of infected material when transfer
loops are sterilized,However,microincinerators can
disturb the airflow and should therefore be placed towards
the back of the work surface in biological safety cabinets.
Personal protective equipment and clothing
Personal protective equipment and clothing may act as a
barrier to minimize the risk of exposure to aerosols,
splashes and accidental inoculation,The clothing and
equipment selected is dependent on the nature of the work
performed,Protective clothing should be worn when
working in the laboratory,Before leaving the laboratory,
protective clothing should be removed,and hands should
be washed,
Table 11 summarizes some personal protective equipment
used in laboratories and the protection afforded.
Laboratory coats,gowns,coveralls,aprons
Laboratory coats should preferably be fully buttoned,
However,long-sleeved,back- opening gowns or coveralls
give better protection than laboratory coats and are
preferred in microbiology laboratories and when working
at the biological safety cabinet.
Aprons may be worn over laboratory coats or gowns
where necessary to give further protection against spillage
of chemicals or biological materials such as blood or
culture fluids,Laundering services should be provided
at/near the facility,Laboratory coats,gowns,coveralls,or
aprons should not be worn outside the laboratory areas.
Goggles,safety spectacles,face shields
The choice of equipment to protect the eyes and face from
splashes and impacting objects will depend on the activity
performed,Prescription or plain eye glasses can be
manufactured with special frames that allow lenses to be
placed in frame from the front,using shatterproof
material either curved or fitted with side shields (safety
glasses).
Safety spectacles do not provide for adequate splash
protection even when side shields are worn with them,
Goggles for splash and impact protection should be worn
over normal prescription eye glasses and contact lenses
(which do not provide protection against biological or
chemical hazards),Face shields (visors) are made of
shatterproof plastic,fit over the face and are held in place
by head straps or caps.
Goggles,safety spectacles,or face shields should not be
worn outside the laboratory
areas.
Respirators
Respiratory protection may be used when carrying out
high-hazard procedures (e.g,cleaning up a spill of
infectious material),The choice of respirator will depend
on the type of hazard(s),Respirators are available with
interchangeable filters for protection against gases,
vapours,particulates and microorganisms,It is imperative
that the filter is fitted in the correct type of respirator,
To achieve optimal protection,respirators should be
individually fitted to the operator’s face and tested,Fully
self-contained respirators with an integral air supply
provide full protection,
Advice should be sought from a suitably qualified person,
e.g,an occupational hygienist,for selection of the correct
respirator,Surgical type masks are designed solely for
patient protection and do not provide respiratory
protection to workers,
Some single-use disposable respirators (ISO 13.340.30)
have been designed for protection against exposures to
biological agents,Respirators should not be worn outside
the laboratory areas.
Gloves
Contamination of hands may occur when laboratory
procedures are performed,Hands are also vulnerable to
“sharps” injuries,
Disposable microbiologically approved latex,vinyl or
nitrile surgical-type gloves are used widely for general
laboratory work,and for handling infectious agents and
blood and body fluids,Reusable gloves may also be used
but attention must be given to their correct washing,
removal,cleaning and disinfection.
Gloves should be removed and hands thoroughly washed
after handling infectious materials,working in a biological
safety cabinet and before leaving the laboratory,Used
disposable gloves should be discarded with infected
laboratory wastes,
Allergic reactions such as dermatitis and immediate
hypersensitivity have been reported in laboratory and
other workers wearing latex gloves,particularly those with
powder,Alternatives to powdered latex gloves should be
available.
Stainless steel mesh gloves should be worn when there is a
potential exposure to sharp instruments e.g,during
postmortem examinations,Such gloves protect against
slicing motion but do not protect against puncture injury,
Gloves should not be worn outside the laboratory areas.
As aerosols are important sources of infection,care should
be taken to reduce the extent of their formation and
dispersion,Hazardous aerosols can be generated by many
laboratory operations,e.g,blending,mixing,grinding,
shaking,stirring,sonicating and centrifuging of infectious
materials,Even when safe equipment is used,it is best to
carry out these operations in an approved biological safety
cabinet whenever possible.
Biological safety cabinets and their use and testing are
discussed in Chapter 10,The use of safety equipment is no
assurance of protection unless the operator is trained and
uses proper techniques,Equipment should be tested
regularly to ensure its continued safe performance.
Table 10 provides a checklist of safety equipment designed
to eliminate or reduce certain hazards and briefly outlines
the safety features,
Negative-pressure flexible-film isolators
The negative-pressure flexible-film isolator is a self-
contained primary containment device that provides
maximum protection against hazardous biological
materials,It may be mounted on a mobile stand,The
workspace is totally enclosed in a transparent
polyvinylchloride (PVC) envelope suspended from a steel
framework,
The isolator is maintained at an internal pressure lower
than atmospheric pressure,Inlet air is passed through one
HEPA filter and outlet air is passed through two HEPA
filters,thus obviating the need to duct exhaust air outside
the building,The isolator may be fitted with an incubator,
microscope and other laboratory equipment,such as
centrifuges,animal cages,heat blocks,etc,
Material is introduced and removed from the isolator
through supply and sample ports without compromising
microbiological security,Manipulations are performed
using gloved sleeves incorporating disposable gloves,A
manometer is installed to monitor envelope pressure.
Flexible-film isolators are used to manipulate high-risk
organisms (Risk Groups 3 or 4) in field work where it is
not feasible or appropriate to install or maintain
conventional biological safety cabinets.
Pipetting aids
A pipetting aid must always be used for pipetting
procedures,Mouth pipetting must be strictly forbidden.
The importance of pipetting aids cannot be
overemphasized,The most common hazards associated
with pipetting procedures are the result of mouth suction,
Oral aspiration and ingestion of hazardous materials have
been responsible for many laboratory-associated infections.
Pathogens can also be transferred to the mouth if a
contaminated finger is placed on the suction end of a
pipette,A lesser known hazard of mouth pipetting is the
inhalation of aerosols caused by suction,
The cotton plug is not an efficient microbial filter at
negative or positive pressure,and particles may be sucked
through it,Violent suction may be applied when the plug is
tightly packed,resulting in the aspiration of plug,aerosol
and even liquid,The ingestion of pathogens is prevented
by the use of pipetting aids.
Aerosols can also be generated when a liquid is dropped
from a pipette on to a work surface,when cultures are
mixed by alternate sucking and blowing,and when the last
drop is blown out of a pipette,
The inhalation of aerosols unavoidably generated during
pipetting operations can be prevented by working in a
biological safety cabinet,
Pipetting aids should be selected with care,Their design
and use should not create an additional infectious hazard
and they should be easy to sterilize and clean,Plugged
(aerosol-resistant) pipette tips should be used when
manipulating microorganisms and cell cultures.
Pipettes with cracked or chipped suction ends should not
be used as they damage the seating seals of pipetting aids
and so create a hazard.
Homogenizers,shakers,blenders and sonicators
Domestic (kitchen) homogenizers are not sealed and
release aerosols,Only equipment designed for laboratory
use should be used,
Their construction minimizes or prevents such release,
Stomachers,which are now available for use with large
and small volumes,may also produce aerosols.
Homogenizers used for Risk Group 3 microorganisms
should always be loaded and reopened in biological safety
cabinets.
Sonicators may release aerosols,They should be operated
in biological safety cabinets or covered with shields during
use,The shields and outsides of sonicators should be
decontaminated after use.
Disposable transfer loops
The advantage of disposable transfer loops is that they do
not have to be sterilized and can therefore be used in
biological safety cabinets where Bunsen burners and
microincinerators would disturb the airflow,These loops
should be placed in disinfectant after use and discarded as
contaminated waste
Microincinerators
Gas- and electrically-heated microincinerators have
borosilicate glass or ceramic shields that minimize the
spatter and dispersal of infected material when transfer
loops are sterilized,However,microincinerators can
disturb the airflow and should therefore be placed towards
the back of the work surface in biological safety cabinets.
Personal protective equipment and clothing
Personal protective equipment and clothing may act as a
barrier to minimize the risk of exposure to aerosols,
splashes and accidental inoculation,The clothing and
equipment selected is dependent on the nature of the work
performed,Protective clothing should be worn when
working in the laboratory,Before leaving the laboratory,
protective clothing should be removed,and hands should
be washed,
Table 11 summarizes some personal protective equipment
used in laboratories and the protection afforded.
Laboratory coats,gowns,coveralls,aprons
Laboratory coats should preferably be fully buttoned,
However,long-sleeved,back- opening gowns or coveralls
give better protection than laboratory coats and are
preferred in microbiology laboratories and when working
at the biological safety cabinet.
Aprons may be worn over laboratory coats or gowns
where necessary to give further protection against spillage
of chemicals or biological materials such as blood or
culture fluids,Laundering services should be provided
at/near the facility,Laboratory coats,gowns,coveralls,or
aprons should not be worn outside the laboratory areas.
Goggles,safety spectacles,face shields
The choice of equipment to protect the eyes and face from
splashes and impacting objects will depend on the activity
performed,Prescription or plain eye glasses can be
manufactured with special frames that allow lenses to be
placed in frame from the front,using shatterproof
material either curved or fitted with side shields (safety
glasses).
Safety spectacles do not provide for adequate splash
protection even when side shields are worn with them,
Goggles for splash and impact protection should be worn
over normal prescription eye glasses and contact lenses
(which do not provide protection against biological or
chemical hazards),Face shields (visors) are made of
shatterproof plastic,fit over the face and are held in place
by head straps or caps.
Goggles,safety spectacles,or face shields should not be
worn outside the laboratory
areas.
Respirators
Respiratory protection may be used when carrying out
high-hazard procedures (e.g,cleaning up a spill of
infectious material),The choice of respirator will depend
on the type of hazard(s),Respirators are available with
interchangeable filters for protection against gases,
vapours,particulates and microorganisms,It is imperative
that the filter is fitted in the correct type of respirator,
To achieve optimal protection,respirators should be
individually fitted to the operator’s face and tested,Fully
self-contained respirators with an integral air supply
provide full protection,
Advice should be sought from a suitably qualified person,
e.g,an occupational hygienist,for selection of the correct
respirator,Surgical type masks are designed solely for
patient protection and do not provide respiratory
protection to workers,
Some single-use disposable respirators (ISO 13.340.30)
have been designed for protection against exposures to
biological agents,Respirators should not be worn outside
the laboratory areas.
Gloves
Contamination of hands may occur when laboratory
procedures are performed,Hands are also vulnerable to
“sharps” injuries,
Disposable microbiologically approved latex,vinyl or
nitrile surgical-type gloves are used widely for general
laboratory work,and for handling infectious agents and
blood and body fluids,Reusable gloves may also be used
but attention must be given to their correct washing,
removal,cleaning and disinfection.
Gloves should be removed and hands thoroughly washed
after handling infectious materials,working in a biological
safety cabinet and before leaving the laboratory,Used
disposable gloves should be discarded with infected
laboratory wastes,
Allergic reactions such as dermatitis and immediate
hypersensitivity have been reported in laboratory and
other workers wearing latex gloves,particularly those with
powder,Alternatives to powdered latex gloves should be
available.
Stainless steel mesh gloves should be worn when there is a
potential exposure to sharp instruments e.g,during
postmortem examinations,Such gloves protect against
slicing motion but do not protect against puncture injury,
Gloves should not be worn outside the laboratory areas.
