Silver News
Silver Brings Health and Wealth in Mexico
By Samuel Etris, Senior Technical Consultant to The Silver
Institute
Mexico has maintained its leadership position in worldwide
production of silver for generations. In the year past, Mexico
entered some 88 million ounces of silver into the market,
valued at over $380 million, a significant addition to the
Mexican economy. History reveals that nearly one third of
0 the world's silver has been mined in the Mexican Cordillera.
However, silver's contribution to Mexico's citizens extends
far beyond the economic; it contributes to their health as
well. Since ancient times Mexicans have used silver vessels
to keep water fresh and milk sweet. Since 1955, with the approval
of the Ministry of Health of Mexico, Microdyn, a silver colloid,
with a particle size of about 2 manometers, has been used
to provide healthful water for its citizens.
"A few drops of Microdyn available in small bottles provides
sufficient silver to disinfect clear drinking water in about
10 minutes," states Luis Arizcorreta Buchholz, president
of Roland de Mexico, S.A, de C.V, Mexico D.E, Mexico. "It
is a convenient disinfectant for individual use in areas wherever
tap water is suspect. Microdyn has also found wide popularity
in Mexico as a rinse to disinfect fruit and vegetables. It
is also active against spores and parasites."
Microdyn is also made available in a soluble carrier which
is painted on the interior of cisterns for the long-term disinfection
of drinking water. Its use is credited with a dramatic improvement
in the health of the residents of the town of Cruz Azul, Lagunas,
Oaxaca, Mexico, who for years had suffered rampant gastroenteritis.
The introduction of a Microdyn coating to the town's water
supply cisterns in 1977 made the difference. Other local water
supply systems treated with Microdyn achieved similar results.
A study by Microbiological Research & Development Inc.
of Tucson, Arizona, proved the relative power of Microdyn
against that of chlorine. At the 0.025 milligram per liter
(mg/liter) level of Microdyn silver (the United States Environmental
Protection Agency suggested limit for silver in drinking water
is 0. 100 mg/liter], water charged with 2, 700 units per liter
of the fecal conform Echerichia coli (E.Coli) bacterium was
completely sterilized in less than three hours, whereas the
chlorine to sterilize the same charge of bacterium over the
same period of time required 40 times greater concentration.
In another test, water charged with 100 times that amount
of fecal coliform required 8 times the normal concentration
of Microdyn for complete sterilization, whereas 10 times the
concentration of chlorine was required. In every case, the
disinfectant power of Microdyn was greater than that of chlorine.
Silver's antibacterial power is so strong that Microdyn contains
only 3,575 parts per billion of silver per liter, or less
than 2 milligrams silver per liter-sized bottle.
In a related story, NVID International, Inc. of Clearwater,
Florida, announced the successful completion of testing of
a municipal drinking water system utilizing ionic silver,
in the city of Celaya, Mexico. The test was designed to test
a three-block section of the distribution-piping grid for
this city of 350,000 residents. The test commenced on March
8 under the auspices of the City of Celaya, and the state
branches of Commission National de Aug (CNA) and Salute de
Ambiental (Mexican EPA).
The Company's Ionic Disinfection System was installed on one
of the 65 wells serving the city's residents and the system
injected 10 parts per billion of ionic silver into the distribution
grid. Within 24 hours of installing the system, the fecal
conform count was brought to zero and it remained at zero
for the next eighteen days. The system was then taken off-line
and the fecal conforms returned within two days. The system
was reconnected to the distribution grid and again obtained
zero fecal coliform within 24 hours and kept the count at
zero for the next 45 consecutive days.
NVID's President, David Larson stated, "This test was
very significant due to the low levels of ionic silver used
in the disinfection. In the United States, the Environmental
Protection Agency (EPA) recommended the allowable levels of
silver present in drinking water be set at 100 ppb, and most
of the Company's systems are designed to inject ionic silver
well below the limit, at a rate of 60 ppb. Proving efficacy
at 10 ppb is significant in that cost comparisons with traditional
disinfectants such as Chlorine become more favorable and the
initial capital outlay for end users is greatly reduced."
The use of silver as a biocide in water treatment is growing.
In 2000, about 5.3 million ounces were used for water treatment
with estimates of 6.16 million for 2002, 7.1 million for 2004
and 8.1 million in 2006, according to Jeffrey Ellis, Adjunct
Professor of Chemistry at Florida International University
in Miami, a consultant to the chemical and plastics industry.
Silver News - August / September 2001
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