Systematic Evaluation of the Efficacy of Chlorine Dioxide in Decontamination of Building Interior Surfaces Contaminated with Anthrax Spores

Abstract

Efficacy of chlorine dioxide (CD) gas generated by two distinct generation systems, Sabre (wet system with gas generated in water) and ClorDiSys (dry system with gas generated in air), was evaluated for inactivation of Bacillus anthracis spores on six building interior surfaces. The six building materials included carpet, acoustic ceiling tile, unpainted cinder block, painted I-beam steel, painted wallboard, and unpainted pinewood. There was no statistically significant difference in the data due to the CD generation technology at a 95% confidence level. Note that a common method of CD gas measurement was used for both wet and dry CD generation types. Doses generated by combinations of different concentrations of CD gas (500, 1,000, 1,500, or 3,000 parts per million of volume [ppmv]) and exposure times (ranging between 0.5 and 12 h) were used to evaluate the relative role of fumigant exposure period and total dose in the decontamination of building surfaces. The results showed that the time required to achieve at least a 6-log reduction in viable spores is clearly a function of the material type on which the spores are inoculated. The wood and cinder block coupons required a longer exposure time to achieve a 6-log reduction. The only material showing a clear statistical difference in rate of decay of viable spores as a function of concentration was cinder block. For all other materials, the profile of spore kill (i.e., change in number of viable spores with exposure time) was not dependent upon fumigant concentration (500 to 3,000 ppmv). The CD dose required for complete spore kill on biological indicators (typically, 1E6 spores of Bacillus atrophaeus on stainless steel) was significantly less than that required for decontamination of most of the building materials tested.

Low-Temperature Decontamination with Hydrogen Peroxide or Chlorine Dioxide for Space Applications

“…Gaseous hydrogen peroxide (10,17,20,29) and chlorine dioxide technologies (6,10,19,34,39) have been shown to be effective against a wide range of bacterial and viral organisms.…”

Gaseous Decontamination Methods in High-containment Laboratories

“…Similar to VHP/HPV, GCD was also found to have decreased efficacy on porous materials such as wood, cinderblock, and paper (Han et al, 2003;Krishnan et al, 2006b;Rastogi et al, 2009;Rastogi et al, 2010). Greater variability in organism inactivation was also observed on porous materials, which the authors attribute to the microscopic pores and structural non-uniformity of complex materials (Rastogi et al, 2010).…”

“…Similar to VHP/HPV, GCD was also found to have decreased efficacy on porous materials such as wood, cinderblock, and paper (Han et al, 2003;Krishnan et al, 2006b;Rastogi et al, 2009;Rastogi et al, 2010). Greater variability in organism inactivation was also observed on porous materials, which the authors attribute to the microscopic pores and structural non-uniformity of complex materials (Rastogi et al, 2010). Conversely, organisms on nonporous materials such as glass and stainless steel were found to require much shorter inactivation times (Han et al, 2003;Krishnan et al, 2006b;Rastogi et al, 2009;Rastogi et al, 2010).…”

“…Although the generation methods are different, the end product (chlorine dioxide) and decontamination conditions are es- sentially the same. In a report comparing the efficacy of these two methods, no significant differences were found (Rastogi et al, 2010). Decontamination cycles for both generators consist of five phases beginning with pre-conditioning, in which the relative humidity of the area is raised to >70%.…”

Inactivation Kinetics and Mechanism of a Human Norovirus Surrogate on Stainless Steel Coupons via Chlorine Dioxide Gas

“…However, in order to eliminate bacterial spores, elevated gas concentrations and longer treatment times are necessary (37)(38)(39). Overall, fungi have been shown to be more resistant than vegetative bacteria to ClO 2 gas treatment.…”