SummaryIn work environments with laboratory animals, the bedding of animals binds the excreta as well as other compounds originating from the animals and their environment. These may be generated into the ambient air when the personnel handle bedding in different procedures. This study compares the dustiness of different types of six clean and four soiled beddings from rat or mouse cages. The dust generation of clean bedding varied from <1 to 25 mg=m 3 . When used in the cages of rats or mice for 4 days, the dust concentration of the beddings decreased, increased or stayed the same, depending on the type of bedding and animal species. A decrease in dustiness was, however, more common. The levels in the soiled beddings varied from <1 to 8.6 mg=m 3 . In the case of the aspen chip bedding, the contents of bedding used in mouse, rat or rabbit cages were analysed for mesophilic bacteria and fungi, mycobacteria and endotoxins. All of these contaminants were variably found in the bedding samples, the maximal concentrations for bacteria were >6 500 000 colony-forming units (cfu)=g, for fungi 212 000 cfu=g, and for endotoxins 6500 ng=g (81 000 EU=g). The results showed that the bedding of laboratory animals may contain biologically effective compounds, and that these may be distributed into the ambient air depending on the characteristics of the bedding material. The dustiness of different bedding types is an important factor affecting the amount and quality of the occupational exposure of the personnel to airborne contaminants.
SummaryBesides the well known allergens, several other risk factors may exist for health in a laboratory anim al unit. T he exposure to these factors may be signi®cant in animal units with poor general or local ventilation systems. Moreover, means to prevent the distribution of airborne contaminants may be limited in animal units housing rabbit s or other bigger laboratory animals. Airborne contaminants in conventional laboratory rabbi t rooms were sought to evaluate the occupational exposure of animal care personnel. Concentrations of airborne dust, bac teria, fungi, ammonia and endotoxins were measured during 2 days in three phases: before working acti vities began, during them and aft erwards. Both stati onary and some personal samples were taken. All of the contam inants sought were found in the rabbi t room air. When compared to reported levels in farm animal production areas, the concentrations measured were generally low. However, moderate or high levels of airborne bac teria and fungi were found occasionally during work routines. Airborne contaminants should be considered as a potential occupational health risk for persons working with laboratory animals.
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