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Washing/Drying of Clothing Contaminated with a Biological Agent Such as Bacillus anthracis
Citation:
TOUATI, A., S. Serre, AND J. Wood. Washing/Drying of Clothing Contaminated with a Biological Agent Such as Bacillus anthracis. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-20/217, 2020.
Impact/Purpose:
A large-area accidental or intentional release of Bacillus anthracis (Ba) spores may subject emergency response teams as well as the general public to exposure and cross-contamination through personal protective equipment (PPE) or personal clothing. The overall purpose of this study was to assess the use of washers and dryers with a suitable decontamination solution as a potential self-help practice to reduce and/or inactivate biological spores from common clothing material. This approach may be used to lessen potential cross-contamination among emergency first-responders, security personnel, or public citizens exposed to a wide area B. anthracis spore release.
Description:
The study was conducted in four phases, each using viable spores of Bacillus atrophaeus var. globigii (Bg), a surrogate for Ba. Phase I and II were part of a bench-scale study using a Lab Line Incubator-Orbital Shaker to simulate a washing machine. The experiment was conducted using 300-ml liquid inoculated wash solutions in 500-ml Nalgene bottles placed on the orbital shaker platform. In Phase I, potential decontamination solutions were identified, then inoculated with Bg spores and quantitatively assessed for inactivation efficacy. In Phase II, experimental cloth coupons were inoculated with Bg spores, then exposed to the most efficacious solutions identified in Phase I. Phase III and IV were part of a pilot-scale study in which off-the-shelf mini-washers and dryers were used. Phase III experiments were conducted using a portable mini compact twin tube washer spin dryer. Phase IV was conducted using the previous compact washer along with a standalone front load compact laundry dryer. Results from the first phase indicated that oxygen-based diluted (10%) bleach solutions were not sporicidal, but full decontamination was observed for the chlorine-based diluted bleach solution. The effect of temperature on the decontamination efficacy of the wash solutions was found to be negligible for the two temperatures evaluated. Phase II experiments used a simulated washing procedure and small cloth coupons and confirmed results from the Phase I tests that the 1% chlorine-based bleach solution was a highly effective decontamination approach. Results from Phase III confirmed that 1% diluted chlorine-based bleach solution with the addition of a detergent using an 18-minute wash time was very effective in decontaminating material fabric inoculated with ~107 spores per square foot. All materials had surface log reductions > 6. The addition of a drying sequence in Phase IV resulted in no apparent increase in the decontamination efficacy of the diluted bleach solution.