Analysis of Range and Use of a Hybrid Hydrogen Peroxide System for Biosafety Level 3 and Animal Biosafety Level 3 Agriculture Laboratory Decontamination.

Introduction: The applications of fumigation and the challenges that high-containment facilities face in achieving effective large volume decontamination are well understood. The Biosecurity Research Institute at Kansas State University sought to evaluate a novel system within their biosafety level 3 (BSL-3) and animal biosafety level 3 agriculture (ABSL-3Ag) facility. Methods: The system chosen for this study is the CURIS® Hybrid Hydrogen PeroxideTM (HHPTM) system, comprising a mobile 36-pound (16 kg) device delivering a proprietary 7% hydrogen peroxide (H2O2) solution. To examine the system's efficacy in multiple laboratory settings, two BSL-3 laboratories (2,281 [65 m3] and 4,668 ft3 [132 m3]) with dropped ceiling interstitial spaces and an ABSL-3Ag necropsy suite (44,212 ft3 [1,252 m3]) with 21-foot (6.4 m) ceilings were selected. Biological indicators (BIs) of Geobacillus stearothermophilus (1.7 × 106 organisms) on steel spore carriers and H2O2 chemical indicators (CIs) were used to provide validation. Results: After cycle optimization, the smaller laboratory had a total of 60 BIs over two treatments that demonstrated a greater than 6-log reduction of bacterial spores. The larger laboratory (192 BIs) and the necropsy suite (206 BIs) had no BIs positive for spore growth when incubated at 60°C for 24 h per manufacturer's specifications. Conclusion: Overall successful results through multiple components of this study demonstrate that the HHP device, paired with the pulsed 7% H2O2 solution, achieved efficacy regardless of variables in laboratory size and layout. Perceived challenges such as 21-ft (6.4 m) ceiling heights, active equipment, and difficult to access ceiling interstitial spaces proved unfounded. Given the successful sterilization of all challenged BIs, the HHP system presents a useful alternative for high level decontamination within BSL-3 and ABSL-3Ag facilities.

Challenges and Solutions With Agricultural Animal High Containment Waste Disposal.

Waste disposal in Agricultural Animal High Containment Animal Biosafety Level 3Ag and Animal Biosafety Level 4Ag (ABSL-3Ag and ABSL-4Ag) research facilities necessitates significantly more attention to detail in operations than that required in lower-containment-level laboratories. The unique features and requirements of agricultural-related research involve additional equipment and systems to safely transfer decontaminated waste out of the facility. The waste stream coming from ABSL-3Ag and ABSL-4Ag facilities, or high containment agricultural research waste, consists of many forms and differs from most research facility waste in that it is produced from research with livestock or other species loose housed, with the animal room serving as primary containment. This is in contrast to small laboratory animals being housed in primary containment caging. Waste handling equipment in agricultural research facilities may include autoclaves, effluent decontamination systems, incinerators, high-temperature renderers, alkaline tissue digester systems, high-efficiency particulate air filtration of exhaust and supply air, gas decontamination systems, and laundry facilities. This article focuses primarily on the disposal of waste from ABSL-3Ag livestock facilities, including procedures and lessons learned over 10 years of facility operation.

Hydrogen Peroxide Methods for Decontaminating N95 Filtering Facepiece Respirators.

Introduction: During a pandemic, when the supply of N95 filtering facepiece respirators (FFRs) is limited, FFRs may be decontaminated by methods that inactivate pathogens as long as they do not damage FFR function. Hydrogen peroxide (H2O2) is widely used for decontamination in medical settings. Objective: To review the literature on the use of H2O2 to decontaminate N95 FFRs and identify methods that inactivate virus and preserve FFR filtration efficiency and fit. Methods: The literature was searched for studies evaluating H2O2 decontamination methods on inactivating SARS-CoV-2 and other viruses and microorganisms inoculated on N95 FFRs and the effects on respirator filtration efficiency and fit. Current U.S. Federal guidelines are also presented. Results: Findings from relevant laboratory studies (N = 24) are summarized in tables. Commercially available H2O2 decontamination systems differ on how H2O2 is delivered, the temperature, the duration of treatment, and other factors that can impact N95 FFR filtration efficiency and fit. Some methods inactivate SARS-CoV-2 virus-contaminated N95 FFRs with >3 log attenuation, whereas other methods are yet to be evaluated. Discussion and Conclusion: Most of the H2O2 methods reviewed effectively decontaminate N95 FFRs without damaging FFR function. However, some methods adversely impact N95 fit or filtration efficiency, which could go undetected by the end user and compromise their protection from pathogen inhalation. When making decisions about H2O2 decontamination of respirators, it is important to understand differences in methods, effects on different FFR models, and potential hazards to workers who manage the decontamination process.

DNA adducts and liver DNA replication in rats during chronic exposure to N-nitrosodimethylamine (NDMA) and their relationships to the dose-dependence of NDMA hepatocarcinogenesis.

Exposure of rats to the hepatocarcinogen N-nitrosodimethylamine (NDMA) (0.2-2.64 ppm in the drinking water) for up to 180 days resulted in rapid accumulation of N7- and O6-methylguanine in liver and white blood cell DNA, maximum adduct levels being reached within 1-7 days, depending on the dose. The levels of both adducts remained constant up to treatment day 28, subsequently declining slowly to about 40% of maximal levels for the liver and 60% for white blood cells by day 180. In order to elucidate the role of DNA replication in NDMA hepatocarcinogenesis, changes in liver cell labeling index (LI) were also measured on treatment days 21, 120 and 180. Although the time- and dose-dependence of the observed effects were complex, a clear trend towards increased rates of hepatocyte LI, as indicated by BrdU incorporation, with increasing NDMA doses was evident, particularly above 1 ppm, a concentration above which NDMA hepatocarcinogenicity is known to increase sharply. In contrast, no increase in Kupffer cell DNA replication was found at any of the doses employed, in accordance with the low susceptibility of these cells to NDMA-induced carcinogenesis. No significant increase in the occurrence of necrotic or apoptotic cells was noted under the treatment conditions employed. These results suggest that, in addition to the accumulation of DNA damage, alterations in hepatocyte DNA replication during the chronic NDMA exposure may influence the dose-dependence of its carcinogenic efficacy.