# How Working Tasks Influence Biocontamination in an Animal Facility
## 4 Discussion  
To the best of our knowledge, this is the first Italian study which assesses the exposure to biological agents in a conventional animal facility, taking into account the biocontamination of different occupational areas in conjunction with the effect of specific working tasks, cage changing frequency and animal strains on it. The most frequent genera identified in this study are common skin inhabitants and are thus easily shed into the environment on desquamated epithelial skin cells. Some bacterial species have been \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Workplace** & **Endotoxin** & **(1,3)-\(\beta\)-n-glucan** & **Rat n 1** & **Mus m 1** \\  & **(EU/m\({}^{3}\))** & **(ng/m\({}^{3}\))** & **(ng/m\({}^{3}\))** & **(ng/m\({}^{3}\))** \\ \hline Animal rooms & & & & \\ Before & \(5.2\pm 3.7\) & \(0.8\pm 0.5\) & & \(0.1\pm 0.1\) \\ During & \(7.1\pm 3.8\) & \(2.4\pm 1.9\) & \(0.4\pm 0.6\) & \(10.5\pm 17.4\) \\ After & \(5.4\pm 3.5\) & \(1.4\pm 0.6\) & & \(2.2\pm 5.3\) \\ \hline Storage area & & & & \\ Morning & \(37.8\pm 37.3\) & \(3.5\pm 2.4\) & & \(0.9\pm 0.0\) \\ Afternoon & \(210.7\pm 20.0\) & \(4.3\pm 1.6\) & & \(2.2\pm 0.0\) \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Concentrations (mean value and standard deviation) of inhalable endotoxin, (1,3)-\(\beta\)-n-glucan, Rat n 1 and Mus m 1 by working activities. reported to cause a variety of diseases, ranging from pneumonia (_Acinetobacter_) to intestinal infections (_E. coli_) ([[https://www.cdc.gov](https://www.cdc.gov)]([https://www.cdc.gov](https://www.cdc.gov))). Other microorganisms, such as _Enterobacter_ and _Pseudomonas_, exhibit a high degree of biological activity, are producers of endotoxin, and often show strong allergenic properties that increase the risk of disease in workers [46; 47]. However, colonies of bacterial species belonging to risk group 2, according to the Italian Legislative Decrees 81/2008 and 106/2009 [44; 45], have been isolated in some animal rooms during the changing cages. With regard to endotoxin, no regulatory value is currently available, but various recommendations are available. Among them, Dutch Expert Committee on Occupational Standards recommends an occupational exposure limit of 90 EU/m\({}^{3}\)[48]. Endotoxin concentrations measured in this study were below this standard in all settings except for the storage area during activities where a mean value of 210.6 EU/m\({}^{3}\) was observed. Our data confirm what was reported by [PERSON] et al., 2002 [33], that bedding material could be a significant source of accumulation and release of bacterial endotoxins. This evidence was demonstrated also by [PERSON] et al., 2010 [49] who measured a range of endotoxins between 3121 and 5401 EU/g in hardwood rodent bedding. Endotoxin concentrations measured in this study are higher than those reported by [PERSON] et al., 2016 [50], who found a mean value of 0.14 EU/m\({}^{3}\) (range = 0.03-0.60 EU/m\({}^{3}\)) in an animal laboratory housing mice, where the main tasks were feeding/weighing with air exchange rates comparable to ours, and then those reported by [PERSON] et al., 2006 [13] who measured a mean endotoxin concentration of 315 pg/m\({}^{3}\) (about 3.15 EU/m\({}^{3}\)) with a peak value of 678 pg/m\({}^{3}\) (corresponding about 6.78 EU/m\({}^{3}\)) during the changing cages in a mouse facility. Our data are also slightly higher than those reported by [PERSON] et al., 2008 [39] (mean value = 4.7 EU/m\({}^{3}\); range = 3.4-6.3 EU/m\({}^{3}\)) in rabbit rooms; this difference may be attributed to higher mechanical air-change rates (30.3 air changes/h) in the animal housing space. Finally, results of the present study are quite lower than those shown by [PERSON] et al., 2001 [15], who found the highest concentration (15.4 ng/m\({}^{3}\) = 154.7 EU/m\({}^{3}\)) associated with cage cleaning and feeding in animal rooms housing rats.