The bedding of laboratory animals as a source of airborne contaminants

Abstract

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.

Long-term effects of cage-cleaning frequency and bedding type on laboratory rat health, welfare, and handleability: a cross-laboratory study

“…These results are surprising because aspen is generally regarded as relatively nontoxic, but to our knowledge, all previous relevant studies have been brief, and did not use a paper bedding comparable with AlphaDri or Omega-Dri (Tö rrö nen et al 1989, Odynets et al 1991, Holland & Griffin 2000. The histological analysis did not allow us to identify the agent responsible for the pathology, but candidates could include: (a) microorganisms inherent in the material (Ewaldsson et al 2002, Kaliste et al 2004; (b) toxic volatile substances associated with the source material or processing products (Tö rrö nen et al 1989, Odynets et al 1991; and (c) cellulose dust (Milton et al 1990, Tatrai et al 1995, Kaliste et al 2004). Ammonia was not the cause because it neither differed with bedding type nor correlated with sneezing or respiratory pathology.…”

The influence of bedding materials on bio-aerosol exposure in dairy barns

“…Studies in laboratory animal facilities showed that type of bedding materials applied can influence allergen exposure levels. 11,12 This prompted us to hypothesize that bedding materials might be a significant determinant for bioaerosol exposure in cow barns as well.…”

Control of particulate matter emissions from poultry and pig houses

“…By the end of the fattening period, straw bedding became more "dusty" as it was more dirty, disintegrated, and could potentially generate more particles (Aarnink et al, 2004). Type of litter and moisture content may also affect PM concentrations (Kaliste et al, 2004).…”

“…In pig houses, higher PM concentrations are found in systems with bedding than in those with concrete floors (Aarnink et al, 2004). Type of litter and moisture content may also affect PM concentrations (Kaliste et al, 2004).…”

“…For instance, manure drying systems in laying hens in battery cages has shown to reduce ammonia emissions by 6 to 27% compared with non-drying belt system (Groot Koerkamp et al, 1995). As regards to PM, however, this would result in increased levels of PM (Kaliste et al, 2004;Vucemilo et al, 2008). Moreover, the suitability of animal welfare housing systems as regards PM is also questionable.…”