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There has been a great deal of research into the effects
of copper-silver ionization of water on a variety of bacteria and other
infectious agents. ThomsonTec makes no medical or scientific claims, but
provides the following data for informational purposes only.
For more detailed information about silver and its
applications to health, preventing disease outbreaks, and reducing or
replacing the need for chlorine,
click here.
Microbiological Evaluation of Copper:
Silver Disinfection Units
AUTHORS: Kutz SM,
Landeen LK, Yahya MT, and Gerba CP
PUBLICATION: Proceedings of the
Fourth Conference on Progress in Clinical Disinfection. State University
of New York, Bighamton, New York, April 11-13, 1988
PURPOSE:
Although chlorination is the traditional method
of disinfecting swimming pools, hot tubs, and cooling towers to prevent
outbreaks of illness due to pathogenic bacteria, viruses, and protozoa,
high levels of chlorine can cause eye and skin irritation was well giving
rise to a noticeable chlorine odor. The authors evaluated electrolytically
generated copper: silver ions alone and in combination with low levels of
free chlorine as an alternative method of reducing the bacterial
population in water.
MATERIALS AND METHODS:
The test medium was local well water which was subjected to chemical
analysis, filtering, and pH stabilization and used at room temperature.
Suspensions of the following organisms were prepared: Escherichia coli,
Legionella pneumophila, Staphylococcus aureus, Pseudomonas aeruginosa,
Salmonella TYPHII, Klebsiella terrigena, and Streptococcus faecalls.
Approximately 1 ml of the selected bacterial suspension was added to 99 ml
of test medium containing (1) copper: silver ions in a concentration of
400 ug/liter copper to 40 ug/liter silver, (2) free chlorine (0.2
mg/liter) alone, or (3) a combination of copper: silver ions and free
chlorine (quantities as above). Cultures were incubated and the bacterial
colonies enumerated, after which statistical analysis were performed.
RESULTS:
The bacteria tested were inactivated more
rapidly in a solution in which electrolytically generated copper and
silver ions were added to low levels of chlorine than where either method
was used separately. Some organisms were more resistant to treatment than
others. In the experiments with Salmonella typehi and Klebsiella terrigena
no viable cells were recovered after 30 seconds of exposure to either
chlorine alone or to the combined regimen, indicating equal effectiveness
when resistance to disinfection is low. On the other hand, Legionella
pneumophilia titers decreased more than 5 log 10 values after 7 minutes of
exposure to free chlorine (0.2 mg/liters) alone for the same length of
time. Similarly, E. coli numbers were reduced by 4.2 log 10 by the
combination regimen but by less than 3 log 10 after extended exposure to
the copper: silver method without chlorine.
CONCLUSIONS:
The use of electrolytically generated copper
and silver ions in combination with low levels of free chlorine proved an
effective method of killing a wide range of pathogenic bacteria under
controlled test conditions. Such bacteria are of potential concern in
swimming pools and cooling towers.
Inactivation of Poliovirus &
Bacteriophage MS-2 by Copper/Silver and Reduced Levels of Free Chlorine
AUTHORS:
Landeen LK, Yahya MT, and Gerba CP
PUBLICATION REF:
Publication information not available
PURPOSE
OF STUDY:
Viruses tend to be more resistant than bacteria to disinfection regimes.
Although chlorination is widely used to control viral contamination, high
levels of chlorine promote the formation of organic compounds in water
that may be hazardous to human health. An alternative method, copper and
silver ion treatment, is known to be effective against bacteria and algae.
The authors tested electrolytically generated copper and silver ions,
alone and in the presence of reduced levels of free chlorine, in treating
water sample to which either bacteriophage MS-2 or poliovirus had been
added to test effectiveness against viral contamination.
MATERIALS
AND METHODS:
Purified bacteriophage MS-2 and poliovirus type I were prepared by
standard methods in pellet form. The viral pellets were placed in samples
of filtered well water. The virus-containing samples were then exposed to
one of the following treatment regimens: (1) no added disinfectant, i.e.
untreated control; (2) low levels of free chlorine; (3) a combination of
copper: silver with free chlorine; (4) copper: silver ions without
chlorine; or (5) either copper or silver without chlorine. Experiments
were performed in duplicate at room temperature. Linear regression
analysis was performed to calculate the viral inactivation rates for each
treatment regimen.
RESULTS:
The bacteriophage MS-2 inactivation rate for copper alone was
significantly higher when the concentration reached 400 ug/liter. The MS-2
inactivation rate for electrolytically generated copper and silver ions
together was greater than for either metal alone, suggesting an additive
effect. Although not significant for very low levels of chlorine, the
addition of 0.3 mg/liter of free chlorine to a 400/40 ug/liter
copper/silver regimen significantly enhanced MS-2 inactivation rates.
Similarly for poliovirus, the activation rates achieved with the 400/40
copper/silver regimen were significantly greater as compared with
untreated controls. The number of poliovirus were reduced approximately
2.5 log 10 within 72 hours. The addition of 0.3 mg/liter of free chlorine
again improved the inactivation rates achieved, although in this case the
improvement did not reach statistical significance. Poliovirus showed
greater resistance to inactivation by any means tested than did
bacteriophage MS-2.
CONCLUSIONS:
Electrolytically generated copper and silver ions demonstrate efficacy
against bacteriophage MS-2; further improvement occurs with the addition
of reduced levels of free chlorine. The same regimen is capable of
inactivating an enteric virus such as poliovirus in the presence or
absence of free chlorine. The same regimen is capable of inactivating an
enteric virus such as poliovirus in the presence or absence of free
chlorine. Therefore, a regimen in which copper: silver ion treatment is
combined with low levels of chlorine should prove useful as a method of
disinfecting water against viral contamination. |
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US SURVEY OF HOSPITALS
USING COPPER-SILVER IONIZATION FOR THE CONTROL OF LEGIONELLA
September 26-29, 2000,
Janet E. Stout, Y.E. Lin, V.L. Yu
VA Medical Center, Pittsburgh, PA
and
the University of Pittsburgh, Pittsburgh, PA
Despite documentation
of its efficacy in numerous hospitals, the long term efficacy of
copper-silver ionization for controlling Legionella pneumophila in
hospital water distribution systems has not been well documented. We
conducted a survey of the first 13 hospitals in the U.S. that had
implemented copper-silver ionization systems on their hot water systems
for Legionella control. The mean bed size was 434 (range 150-700), 61%
(8/13) performed transplant operations. 100% (13/13) had diagnosed cases
of nosocomial Legionnaires' disease (LD). 30% of the hospitals installed
copper-silver ionization because of problems and expense associated with
the prior use of hyperchlorination. 50% had previously used thermal
eradication. The average number of ionization flow cells installed per
hospital was 3.4 (range 1-7), and the average start-up cost was $86,432.
46% (6/13) of hospitals had >30% of distal outlets positive before using
ionization, and 0% had > 30% positive after installation. For 46% (6/13)
of the hospitals, distal site positivity decreased to 0% positivity. When
we conducted the survey, the ionization systems had been in place from 1
to 4 years. Ionization requires regular maintenance and the pH of water
should be < 8.0 for optimal performance. Ionization is a viable option for
controlling Legionella in hospital water distribution systems.
5th International Conference on Legionella
September 26-29, 2000, Ulm, Germany
Janet E.
Stout
Infectious Disease Section,
University Drive C
Pittsburgh PA 15240USA
Disinfection of
Bacteria In Water Systems by Using Electrolytically Generated Copper:
Silver & Reduced Levels of Free Chlorine
AUTHORS: Yahya MT, Landeen LK,
Mesina MC, Kutz SM, Schultze R, & Gerba CP
PUBLICATION REF: Canadian Journal of
Microbiology 36: 109-116, 1990
PURPOSE:
The recommended minimum level of free chlorine for disinfection of public
swimming pools is 1 mg/liter. This level is difficult to maintain due to
the chlorine-demanding organic material introduced by bathers themselves
as well as the environment. Eye and skin irritation may also occur at the
minimum chlorine level needed for effective disinfection. Electrolytically
generated copper/silver ions are also microbiocidal and are much less
subject to degradation but are slower acting than chlorine. Therefore, the
authors tested the hypothesis that using the two methods together would
accomplish effective disinfection while reducing the level of free
chlorine required.
MATERIALS AND METHODS:
Two 32-gallon plastic containers, one indoors (temperature range 22 to 25)
and the second outdoors exposed to sunlight (temperature range 18 to 36)
were filled with tap water. After chemical analysis and adjustment of pH
and test levels of disinfectants, bath water and urine were added to
stimulate typical swimming conditions. Four treatment regimens were
tested: (1) No added disinfectants (2) Free chlorine alone at the
generally recommended level of 1 mg/liter (3) Free chlorine at 0.3
mg/liter combined with copper and silver ions at a ration of 400 ug/liter
of copper to 40 ug/liter of silver (4) Copper and silver ions alone at the
same ratio as above. An isolate of Staphylococcus sp was employed for
bacterial challenge testing since previous work had shown that
staphylococci are more resistant to disinfection than are coli form
bacteria. The experiment was continued for 12 weeks.
RESULTS:
In the test of free chlorine alone, location proved to be critical. In the
outdoor setting subject to strong sunlight and high temperatures, no
residual chlorine could be detected 3 to 4 hours after optimization.
Indoor, where environmental factors were much less extreme, a residual
level of 0.1 to 0.3 mg/liter was found after 24 hours.
Bacterial counts were kept within drinking water standards (as recommended
for swimming pools) by either high levels of chlorine alone or by the
combination regimen of copper and silver ions with low levels of chlorine:
the difference in total bacterial numbers was not significant. Hen
challenged with Staphylococcus sp isolate, the combination of copper and
silver ions with low levels of chlorine achieved a 2.4 log 10 reduction in
bacterial numbers within 2 minutes, while the single-agent regimes (free
chlorine alone, or copper/silver alone) showed only 1.5 & 0.03 log 10
reductions respectively. Under Staphylococcus sp challenge, the combined
copper/silver and free chlorine had a faster log 10 reduction of microbial
numbers than did treatment with a high level of chlorine alone.
CONCLUSIONS:
The addition of electrolytically generated copper/silver ions in the radio
tested (400 ug/liter copper to 40 ug/liter silver) allowed reduction in
the concentration of free chlorine to one third of the level customarily
recommended. The use of copper/silver may provide resisting protection in
swimming pools after chlorine has been rendered ineffective due to
contamination from swimmers and the natural environment.
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