Chemical and Radioisotope Containment

As with biohazard containment, appropriate equipment and management practices are critical, but the physical characteristics of the facility influence the level of safety that can be attained and the consistency at which it can be maintained. Work with chemicals and radioisotopes in animals may often be carried out safely in conventional animal rooms, however, there are some exceptions. For example, HEPA filtering of exhaust air may be required for working with concentrated levels of especially potent carcinogens, or special shielding may be required for working with certain radioisotopes. It is desirable and sometimes essential to isolate such studies to help prevent cross-contamination. When small numbers of animals are required, it is inefficient to use an entire animal room for a single study. Animal cubicles, semiridged isolators, microisolation cages, etc., can provide the isolation necessary to prevent cross-contamination, while housing multiple studies involving small numbers of animals within a relatively small area as compared with using conventional animal rooms for each study. An area planned for supporting chemical and radioisotope studies may utilize one or more rooms with cubicles or equipped with other containment devices and one or more procedure rooms equipped with radioisotope and chemical fume hoods.

Decontamination of cages can usually be accomplished safely with the use of conventional mechanical cage washers, especially cage and rack washers, taking advantage of the dilution factor that occurs due to the large volume of water used by the washers. Ideally, the chemical and radioisotope containment area should be near the dirty side of the cage sanitation area to minimize the need to transport contaminated cages through corridors (Figure 8.7). Also recommended is a separate room, where contaminated bedding can be removed from cages or pans inside a laminar air flow cabinet in which the aerosolized contaminant is drawn away from the operator into a HEPA filter (Figure 8.4).

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