Chlorine Dioxide Inactivation of Bacterial Threat Agents

Aims: To evaluate the efficacy of chlorine dioxide (ClO(2)) against seven species of bacterial threat (BT) agents in water.

Methods And Results: Two strains of Bacillus anthracis spores, Yersinia pestis, Francisella tularensis, Burkholderia pseudomallei, Burkholderia mallei and Brucella species were each inoculated into a ClO(2) solution with an initial concentration of 2.0 (spores only) and 0.25 mg l(-1) (all other bacteria) at pH 7 or 8, 5 or 25°C. At 0.25 mg l(-1) in potable water, six species were inactivated by at least three orders of magnitude within 10 min. Bacillus anthracis spores required up to 7 h at 5°C for the same inactivation with 2.0 mg l(-1) ClO(2).

Conclusions: Typical ClO(2) doses used in water treatment facilities would be effective against all bacteria tested except B. anthracis spores that would require up to 7 h with the largest allowable dose of 2 mg l(-1) ClO(2). Other water treatment processes may be required in addition to ClO(2) disinfection for effective spore removal or inactivation.

Significance And Impact Of Study: The data obtained from this study provide valuable information for water treatment facilities and public health officials in the event that a potable water supply is contaminated with these BT agents.