Protection against biohazards in animal laboratories

An outline of the animal facilities known as the "Quarters for Experimentally Infected Animals" of the Research Institute for Microbial Diseases, Osaka University, is presented as one example of the approaches used for protecting against biohazards in animal laboratories. The quarters are contained in a 2-story building which is in the form of small cubicles for housing the experimentally infected animals. Each cubicle is equipped with specially designed cabinet compartments in which the animal cages are placed. The anterior surface of the compartments consists of an outward inclining door. Vigorous air-mixing between compartments and the interiors of the cubicles can be avoided by this arrangement. The air for ventilation is sucked through a gap between the edge of the door and the wall of each compartment and the collected air is finally filtered through Cambridge "Aerosolve" and "Absolute" filters before being exhausted into the atmosphere. In the central corridor connecting each cubicle the air pressure is maintained at a higher level than that in the cubicle but lower than that outdoors. Thus, the air stream is always kept flowing from the outside to the inside of the cubicle and from the inside of the cubicle to the compartments but never vice versa. Each cubicle is equipped with an individual, pass-through autoclave. All soiled materials are sterilized before being removed from the cubicle. The drained water from each cubicle is chlorinated in a tank by chloride of lime. In these facilities experimentally infected animals can be handled with little danger of accidental contamination of personnel, other animals, or the external environment. The authors emphasize the importance of complete adherence to the rules in such animal facilities.