Scenario-based assessment of decontamination methodology for biosafety and biosecurity applications

Abstract

Purpose: In laboratory biosafety and in public biosecurity, there is the requirement to call upon effective methods to decontaminate occupied spaces following a biological release. Not all methods will be suitable for a specific environment or against a specific bioagent. Consequently it is important to use realistic scenarios in performance evaluation. Methods & Materials: A range of decontamination methods, including fumigants, spray delivery of disinfectants and physical methods, have been tested using either non-hazardous surrogate biological agents or, under contained conditions, high hazard infectious agents. A controlled environment test chamber was used for initial proof-of-principle evaluations, followed by realistic scenarios to mimic laboratories, offices, domestic rooms, railway carriages and outdoor environments. Decontamination of personal protective suits worn by emergency service workers was also evaluated. Biological test agents were immobilised onto test coupons of material surfaces typical in those environments, or delivered into enclosed spaces as bioaerosols. Log kill achieved by decontamination methods was measured against unexposed controls. Results: Results achieved are a combination of effectiveness and practicality. In laboratory biosafety, room fumigation with complete kill is achievable but some chemical agents are less effective than others against some infectious agents, and can be compromised in some circumstances such as large volumes of spilled biological material. In the wider environment, disinfectant fogging devices can be effective when combined with a systematic clean-up strategy to return the affected area to normal use. Conclusion: The cost and health and safety implications of dealing with an accidental or deliberate biological release are significant. No single decontamination method is universally effective. Therefore it is important to develop a portfolio of methods from which the one most suited to an environment can be selected. Validation of methods using representative scenarios is vital in achieving this.