eBook: Safe and Effective Research in the Vivarium - 8

access the interior of the cage. The added room to
move arms freely above the cage allows the technician to keep arms parallel in the sterile work zone.
Arms movements that involved an incline increase
the risk of air traveling down the arm and out of the
cabinet's front. To ensure that Class II personnel and
product protection are maintained, the user needs
to be protected by a 100 FPM (0.53 micro-siemens)
air barrier through the access opening. Animal handling BSCs often feature pre-filtration systems to
capture large particulates such as animal hair and
dander to extend the supply and Exhaust HEPA filters' life. BSCs are available in different sizes; 4, 5, or
6-feet (1.2, 1.6, or 1.8 m) wide. Often the room size
determines what size BSC can be used.

transport of used cages, bottles, cage enrichment
and discarding of used bedding and disposables.
When working in an ATS or BSC, attention to safety remains necessary. For instance, the following
two routine procedures pose exposure risk for the
operators unless safety precautions are brought in
place: 1) when removing a cage without a lid or cover from an ATS or BSC, the downflow air is pushed
into and out of the cage while moving it out of the
instrument, blowing dust-containing allergens and
possibly microorganisms into the breathing zone of
the vivarium worker; 2) the other often neglected
procedure is the stacking of dirty cages outside the
ATS or BSC. Every time a cage is added to the stack,
it pushes the air from the inside of the dirty cage out
into the environment. The air from the dirty cages
contains a high amount of dust particles with lab
animal allergens and-depending on the experiment-other potentially hazardous agents. For this
reason, it is recommended (and in the case of BSL or
higher conditions, required) to stack cages inside the
ATS or BSC. Also, care should be taken when stacks
of dirty cages, used lids, tops, etc., are removed from
the ATS or BSC.

Most BSCs used for animal work are height-adjustable and have casters for mobility for some movement and cleaning. If they are intended to be used
in alternate locations, each location must be identified, and the BSC certified for proper function in
each area.
Although working in an ATS and BSC may seem similar, each requires specific training. Strict standard
operating procedures (SOPs) should be followed to
maintain the safety level (biocontainment and bioexclusion) needed. BSCs are designed to provide a
higher level of safety and are used for higher-risk
situations compared to ATSs, which are intended
for lower-risk applications. As a consequence, it
may seem more complex to work in a BSC. However,
one should keep in mind that following less strict
work-procedures in an AST results in a higher risk of
infections, cross-contamination, and exposure to lab
animal allergens.

To circumvent these issues by stacking of cages, a
so-called " full cage change " regimen could be used.
In this process, a dirty cage, lid and top are reassembled before it is removed from the AST or BSC
and transported to the washing area. Compared to
fully assembled IVCs (cage and closed lid), stacked
cages takes far less volume per cage. As a consequence, transport and storage of stacked cages are
far more efficient.
As an alternative to the full cage change, dirty cages can be stacked and bagged (as can other materials) before removing them from the AST or BSC.
This is especially effective for single-use cages due
to their high stacking density. Typically, a stack of
25 single-use cages/lids is 20 inches tall. A full stack

Laboratory animal allergen (LAA) is probably the
most prominent OHS health risk in a lab animal facility. Particular attention should be paid to reduce
the risk of exposing people during cage change,

eBook: Safe and Effective Research in the Vivarium

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