Validation Study for the Use of Chlorine Dioxide Gas as a Decontaminant for Biological Safety Cabinets

Abstract

Processes using chlorine dioxide (CD) gas for the biological decontamination of Class II laminar flow biological safety cabinets (BSCs) have been validated following a protocol developed in conjunction with NSF International. This report reviews the protocol and presents the results of the study. Trials were performed in type A1, A2, B1, and B2 cabinets from two different manufacturers. Exhaust and down-flow HEPA filters were pre-loaded with particulates to enhance the validation challenge. Two methods of CD generation were included within the trials, with one involving the injection of a specific mass of CD gas dependent upon the BSC volume, and the other involving the maintenance of a constant CD gas concentration over the duration of the exposure. In each of the more than 40 experimental trials, 12 biological indicators with ∼106 Bacillus atrophaeus endospores were deployed at various locations within the BSC to monitor decontamination efficacy. The study validated and qualified CD as an alternative to formaldehyde gas as a decontaminant for BSCs. Acceptable durations for CD exposure of less than 90 minutes were established. Neither residuals from CD nor cabinet material degradation was observed during the trials.