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Decontamination Options for Bacillus anthracis Contaminated Drinking Water Utilizing Spore Surrogate Studies.

Five parameters were evaluated with surrogates of Bacillus anthracis spores to determine effective decontamination alternatives for use in a contaminated drinking water supply. The parameters were: (1) type of Bacillus spore surrogate (B. thuringiensis or B. atrophaeus); (2) spore concentration in suspension (10(2) to 10(6) spores/ml); (3) chemical characteristics of the decontaminant [sodium dicholor-s-triazinetrione dihydrate (Dichlor), hydrogen peroxide, potassium peroxymonosulfate (Oxone(R)), sodium hypochlorite, and VirkonS(R)]; (4) decontaminant concentration (0.01% to 5%); and (5) exposure time to decontaminant (10 min to 1 hr). Results from 138 suspension tests with appropriate controls are reported. Hydrogen peroxide at a concentration of 5%, and Dichlor and sodium hypochlorite at a concentration of 2%, were highly effective at spore inactivation regardless of spore type tested, spore exposure time, or spore concentration evaluated. This is the first reported study of Dichlor as an effective decontaminant for B. anthracis spore surrogates. Dichlor's desirable characteristics of high oxidation potential, high level of free chlorine, and a more neutral pH than that of other oxidizers evaluated appear to make it an excellent alternative. All three oxidizers were effective against B. atrophaeus spores in meeting the EPA biocide standard of greater than a 6 log kill after a 10-minute exposure time and at lower concentrations than typically reported for biocide use. Solutions of 5% VirkonS(R) and Oxone(R) were less effective as decontaminants than other options evaluated in this study and did not meet the EPA's efficacy standard for a biocide, although they were found to be as effective for concentrations of 10(2) spores/ml. Differences in methods and procedures reported by other investigators make quantitative comparisons among studies difficult. Applied and Environmental Microbiology. 2010;76(19):6631-38.

Author: Raber E, Burklund A

Published: 01/01/2010

Publication Type: Journal article

Publisher: Applied and Environmental Microbiology