After the tragic events of September 11, 2001 in New York and Washington, D.C, the
occurrence of a terrorist act involving the use of biological agents is of particular concern
to water utilities across the United States. Injection of a relatively small amount of
pathogenic agents into a distribution system could impact a large portion of the
population served by a water utility. Endospores of Bacillus anthracis (B. anthracis) are among the pathogenic
microorganisms of most concern due to their high resistance to chemical disinfectants
such as free and combined chlorine. B. anthracis is the microorganism that causes
anthrax, a disease that can be 100% fatal when the toxin-mediated infection reaches the
systemic form. Inhalation anthrax is more dangerous than the cutaneous or
gastrointestinal form. Potential for inhalation related to water could come from exposure
to aerosols formed in sinks, showers or sprinkler systems. The U.S. Defense Department
has estimated that the lethal inhalation dose (LD50) for humans is 8,000 spores, but
studies have shown that doses as low as 9 spores are enough to produce
fatalities in 2% of a population exposed to inhalation anthrax. Furthermore, the lack of
taste and color of contaminated water with these pathogens plus the relative easiness to
produce highly concentrated suspensions make these microorganisms attractive as
biological weapons. Consequently, development of strategies for rapid detection and fast
response in case of occurrence of such an unfortunate, but realistic event are needed.
Based on previous studies,
it appears that potential strategies for decontamination could be based on the sequential
or simultaneous application of chemical disinfectants. These researchers have shown that
limited exposure of C. parvum and B. subtilis to ozone and chlorine dioxide, respectively,
increases significantly the rates of inactivation with free and combined chlorine.
However, a given combination of these disinfectants producing synergy for C. parvum
inactivation might not necessarily result in synergistic effects when used to inactivate B.
subtilis spores. Therefore, sequential disinfection schemes have to be evaluated for each
microorganism.
The main objective of this study was to investigate disinfection strategies for
decontamination of a distribution system in the event of a deliberate injection of B.
anthracis spores. The non-pathogenic B. subtilis spores were used as a conservative
surrogate for B. anthracis spores. Includes 12 references, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 310 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 8 |
| Published : | 06/16/2002 |
