Grantee Research Project Results
Final Report: Whole-Structure Decontamination of Bacillus Spores by Methyl Bromide Fumigation
EPA Contract Number: 68D03056Title: Whole-Structure Decontamination of Bacillus Spores by Methyl Bromide Fumigation
Investigators: Weinberg, Mark J.
Small Business: Cobra Termite Control
EPA Contact: Richards, April
Phase: II
Project Period: October 1, 2003 through December 31, 2004
Project Amount: $218,284
RFA: Small Business Innovation Research (SBIR) - Phase II (2003) Recipients Lists
Research Category: Air Quality and Air Toxics , SBIR - Air Pollution , Small Business Innovation Research (SBIR)
Description:
For 3 years, U.S. government agencies have been challenged by the process of decontaminating buildings of anthrax (Bacillus anthracis) spores. Six federal buildings in the Northeast ultimately were disinfected either with chlorine dioxide gas, vaporized hydrogen peroxide, or ethylene oxide gas (vault fumigation of mail). These current decontamination methods are experimental, costly, and protractive.
Fumigation with a sporicidal gas is the only method that offers simultaneous, “whole-structure” decontamination without the need for localized liquid, foam, or vacuum treatments. For more than 60 years, methyl bromide (MB) has been used as a pest fumigant of soil, foodstuffs, and buildings. The goal of this research project was to present laboratory and field data on the efficacy of MB gas against B. anthracis and allied nonpathogenic spores. Oliver Exterminating Corporation (doing business as Cobra Termite Control) demonstrated how existing technology adapted from the fumigation industry can be used in a rapid and cost-effective manner to employ MB as a structural decontaminant of B. anthracis .
Summary/Accomplishments (Outputs/Outcomes):
Laboratory studies consisted of preparing dried spore suspensions on glass slides, sealing them in 9 L glass chambers , and adding gaseous MB. A minimum effective dose was established that was lethal to 107 spore preparations of B. anthracis (ANR-1 strain) fumigated for 48 hours. Spores of Geobacillus stearothermophilus were slightly more susceptible to MB than B. anthracis, while B. atrophaeus and B. thuringiensis were more resistant to MB. Under these same conditions, different strains of B. anthracis spores (ATCC 10, ATCC 937, ATCC 4728, ATCC 11966, AMES-RIID, ANR-1, STERNE, ATCC 14187, AMES-1-RIID) were killed in both the presence and absence of a 0.5 percent bovine serum, with the exception of strain AMES-RIID (without bioburden), in which a 5.7-log reduction occurred.
In a Florida field trial, a 30,000 ft3 structure was prepared for, fumigated with, and aerated of MB in 1 week. Two hundred surrogate spore coupons, each containing 106 spores of G. stearothermophilus, B. atrophaeus, or B. thuringiensis, were planted in 50 hidden, sealed, or accessible locations within the structure. After fumigation with MB, only one location (a sealed refrigerator) contained viable spores on a single coupon of B. atrophaeus. All electronic equipment and materials fumigated at the same time functioned afterwards and showed no tangible collateral effects.
These findings are innovative in three primary ways: (1) MB has been shown to be toxic to anthrax spores, (2) lethal conditions can be readily replicated in enclosed spaces, and (3) existing or easily modified commercial fumigation techniques can be adapted to yield successful whole-structure decontamination.
Conclusions:
Studies performed by Oliver Exterminating Corporation show that a standard commercial MB fumigation will kill bacterial spores throughout a structure at a concentration lethal to B. anthracis without damage to its contents. Sporicidal fumigations with MB are readily adaptable to large or small structures; vehicles and military hardware (including ships and aircraft); and bulk goods in shipping containers, vaults, or truck trailers. Although not addressed in the current study, nontarget diffusion of MB can be reduced or eliminated by laminating nylon film into a commercial fumigation tarpaulin and using activated charcoal sinks or catalytic scrubbing systems at the end of the fumigation.
MB fumigation is commercially competitive with chlorine dioxide fumigation for anthrax decontamination of buildings and goods because: (1) MB is commercially packaged as a pure liquid in low-pressure metal cylinders; (2) MB converts to a stable, nonreactive gas that maintains constant equilibrium; (3) MB diffuses through densely porous materials and fabrics without loss of efficacy; (4) MB kills by methylation, not oxidation; and (5) monitoring and detection equipment is inexpensive, easy-to-use, and accurate.
Supplemental Keywords:
methyl bromide, MB, anthrax, Bacillus anthracis, chlorine dioxide, decontamination, fumigation, bioterrorism, spores, Geobacillus stearothermophilus, Bacillus atrophaeus, Bacillus thuringiensis, small business, SBIR,, Scientific Discipline, Air, air toxics, Environmental Chemistry, Microbiology, Biochemistry, Environmental Monitoring, Ecological Risk Assessment, Engineering, Chemistry, & Physics, biocontaminant control, building decontamination, homeland security, decontamination, biological warfare agents, bioterrorism, fumigation, anthrax, bacterial spores, biodefense decontamination, Methyl bromide, microbial contaminants, air decontaminationSBIR Phase I:
Whole-Structure Decontamination of Bacillus Spores by Methyl Bromide Fumigation | Final ReportThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.