Effective Decontamination of Laboratory Animal Rooms with Vapour-phase (“Vaporizedâ€) Hydrogen Peroxide and Peracetic Acid

The purpose of this study was to investigate the decontaminant effects of vapour-phase hydrogen peroxide (VHP) and peracetic acid (PAA) in laboratory animal rooms. Methodologically and microbiologically, both methods were evaluated as an alternative to traditional methods. In the VHP decontamination process, the cycle consisted of 4 phases (dehumidification, conditioning, decontamination and aeration). The residual vapour was catalytically decomposed into water and oxygen. The complete process of room decontamination with VHP took 14-15 hours. In PAA decontamination, the dry fog system produced very fine droplets of disinfectant that were dispersed throughout the laboratory animal rooms. The overall decontamination process by PAA mist took 3 hours, which was much faster than VHP decontamination. In both methods, no corrosion appeared on the material surfaces. The results of chemical and biological indicators showed complete decontamination after exposure to VHP and PAA fumigation. In the airborne microbiological examinations, total colony counts for the surface and environmental microorganisms were minimal. There were no significant differences between VHP and PAA fumigation. In laboratory facilities, conventional decontaminating methods will be gradually converted into VHP or PAA decontamination. This experiment confirmed that the VHP method is suitable for the decontamination of a relatively limited space whereas the PAA method is applicable to the rapid decontamination of spacious laboratory animal rooms. In conclusion, decontamination with VHP and PAA holds great promise as an effective alternative to currently used formaldehyde fumigation. Abbreviations ACC: peracetic acid, BIs: biological indicators, CFU: colony-forming units, CIs: chemical indicators, EPA: Environmental Protection Agency, PDACP: potato dextrose agar with chloramphenicol, SCD: soybean casein digest, SCDLP: soybean casein digest with lecithin and polysorbate 80, and VHP: vapour-phase hydrogen peroxide.