Please read and share this important technical report (below the action item and Dr. Rima’s comments) showing that nano silver CANNOT become a threat to aquatic life or soil life. The EPA’s assault is a transparent attempt to shore up the ability of Big Pharma to destroy smaller competitors using government regulatory agencies and “Poison Press” as their weapons.
George J. Maass, Ph.D. (Colloidal Science Laboratories)
Silver is an effective germ fighter and silver nanoparticles are widely recognized
as being especially effective because of their enormously high surface area. Due to the
large number of manufacturers using silver nanoparticles in their products, some concern
has arisen about the effects on the environment when these products are disposed of or
washed. This report will demonstrate that silver nanoparticles do not remain â€œnanosizeâ€
when they come in contact with normal environmental samples, such as soil and water,
but they agglomerate to form much larger, much less biologically effective, silver
particles which are non-toxic, non-ionic and have no history of being harmful to the
environment or aquatic life. Furthermore, there is no possibility that silver nanoparticles
can ever form silver ions, except in the presence of strong oxidizing substances.
Recently, the Environmental Protection Agency (EPA) issued a statement that
they were planning to regulate companies that produce nanoparticles for use as anti-
microbials. This gives rise to the question: why are the dietary supplement and
nanoparticle industries being targeted at this time and what is the rational for new
regulation of an industry which has previously had no reported harmful effects to
humanity or the environment?
The EPA knows that silver nanoparticles are effective as antimicrobials. The
reason given by the EPA for the current interest is that silver nanoparticles, or products
that claim to be silver nanoparticles, are now being produced by a number of
manufacturers, and the EPA is concerned that, when these particles are disposed of, there
might be an appreciable amount of silver nanoparticles suddenly appearing in the
environment. The proposed concern is due to the fact that the silver nanoparticles are so
small that their surface area per unit weight is very large, therefore, for a given weight of
product, the biological effectiveness, which is proportional to surface area, is far beyond
that which would be expected. This much is true and it is part of the reason that silver
nanoparticles are so attractive in biological applications. The EPA is not questioning the
fact that silver nanoparticles are effective in killing harmful bacteria, but that, because of
the high surface area/weight effectiveness parameter, by disposing these particles into
sewers or waterways, might there be harmful effects to the environment by eliminating
the bacteria which are useful in normal waste degradation?
There are several other areas which, as recent articles have indicated, show
misunderstandings about silver and its nanoparticles. At Arizona State University,
Westerhoff and Benn (1) have reported â€œfindingsâ€ which have never been observed
during the last 10 years at Colloidal Science Laboratories (CSL). For example, they claim
that nanosilver particles produce ionic silver when exposed to moisture. This is NOT
true! This is tantamount to saying that silver metal is water soluble. At CSL, various
forms of silver, ranging from solid silver metal to fine silver powder to colloidal
nanoparticles, have been exposed to water for long periods of time with agitation. No
increase in conductivity or silver ion concentration has ever been observed when silver
metal in any form is treated with water. Silver metal requires chemical treatment with
nitric acid or Aqua Regia to make silver ions. Westerhoff and Benn were working with
commercially prepared socks which are prepared by treating the socks with solutions of
silver in questionable form. There may have been some actual colloidal silver in the
treatment solutions, but there most certainly were soluble silver compounds present, and,
once the socks are rinsed, these are the substances which put silver ions back into the
Some people also claim that only silver ions have antimicrobial properties. This
is another misconception. Colloidal silver is a wonderful antimicrobial by itself, which is
a good thing, because silver ions are very reactive with chloride ion to form insoluble,
and biologically inert, silver chloride. This happens in the bloodstream and in nature
wherever halogen anions are present.
As this report will show, the high biological effectiveness of colloidal silver does
not persist in nature because the nanoparticles agglomerate as soon as they come in
contact with the environment, specifically soil and water. Westerhoff and Benn admit that
silver particles â€œclumpâ€ together in the fabric and in the wash water. That is precisely the
point to be considered for environmental safety. How much â€œclumpingâ€ does it take so
that the particles are no longer considered to be â€œnanoâ€, but much larger, therefore
eliminating the continuing effect of high biological activity? These researchers, and
others, are very quick to make the jump from colloidal nanoparticles, in socks for
example, to ionic silver and its toxic effect, especially in zebra fish, and they speak as if
the ions came from the colloidal nanoparticles. It is necessary to be very clear about this.
If the researchers are finding silver ions in the wash water or anywhere else, then the
silver ions were present in the original material. This cannot be stated too strongly.
Unless people have taken to washing their socks in nitric acid, the conversion of
colloidal silver nanoparticles to silver ions is not possible.
The work at hand will examine four different environmental conditions which
change the morphology and stability of silver colloids:
1. The effect of drainage of silver colloids through several soil samples.
2. The effect of interaction of silver colloids with different water
3. The effect of exposure of silver colloids to sunlight.
4. The change in level of silver colloids with regard to biological activity.
At the outset, the first two questions to be addressed were what environmental
samples should be used and to what concentration of colloidal silver should these
samples be exposed. Since this is a first attempt at this kind of information, it was
decided to limit the environmental samples to the following:
1. Sand, taken from the New Jersey shore
2. Dirt, taken from central New Jersey,
3. Dirt, taken from Northern Pennsylvania
4. Water, local tap water from Westampton, NJ
5. Water, sea water, taken from the New Jersey shore
6. Water, taken from a northern Pennsylvania well
The soil samples represent some of the most common types found on the Eastern
Coast of the United States. The sand is essentially an Entisol, which is a type of soil that
is not subject to a great deal of chemical change and is common to areas where deposition
and removal occur at regular intervals. The New Jersey soil is primarily an Ultisol,
which contains clay, quartz, kaolinite and various iron oxides. The Pennsylvania soil is
most likely a mixture of Alfisols and Inceptisols which are clays that are productive for
growing most crops and are common to many areas. (3)
The water samples are Sea water, rich in many salts, NJ tap water, which has been
through routine purification, and Pennsylvania well water, which most likely contains
carbonates and nitrates. Therefore, the selection of samples should be sufficient to
establish the effect of the environment on nanoparticles for this initial study.
Next, in looking at the quantitative amount of colloidal silver to be used, it was
decided that the initial test case should provide information with regard to an
overabundance of nanoparticles being released to the environment, rather than just a trace
amount. If the environment is not substantially altered by the overabundance, surely it
will not be influenced by smaller amounts.
Preliminary work indicated that, at concentrations of up to 6 ppm, and probably
higher, based on the weight of soil samples, no nanoparticles would survive. Therefore, a
more reasonable amount, but still an enormously high concentration for a natural
occurrence, was selected.
Colloidal silver samples at our disposal were of the dietary supplement type and
average at least 20 ppm of silver. Most soil samples require 0.5 to 0.75 their weight in
water to start draining. It was decided that the colloidal silver would be diluted 10 to 1
and then applied to each soil sample. This would make each sample contain a minimum
of 2 ppm of silver nanoparticles, based on the weight of the soil. This would correspond
roughly to dumping 27 liters of 20 ppm colloidal silver onto one ton of dirt. Since most
colloidal silver customers are concerned with teaspoon and tablespoon quantities, it
should be safe to say that this experiment covers something well above the worst case
In each experimental case, the selected sample of colloidal silver was mixed with
the environmental sample and the change in particle size and zeta potential recorded after
a specified time. The instrument used for this work was the Malvern Zetasizer, Model
Nano ZS. Since the samples which were in contact with soil contained very large
macroparticles and rocks, the samples all required vacuum filtration through grade 601
Ahlstrom filter paper to eliminate the particles which are 3 to 4 orders of magnitude
greater than the ones of interest in this study. This filtration has no effect on
For the trials in which the environmental samples were water, the colloidal silver
was diluted 10 to 1 in the water in question.
Table 2 shows that, after only 15 minutes of contact with the soil samples, a
decrease in zeta potential, and the smallest particles have increased to the 3 to 8 nm
range, and they still represent 80 to 90% of the total.
Table 3 indicates that, after a full 7 days of contact with the soil, but kept away
from sunlight, the nanoparticles have increased 3 to 8 times in size.
In Table 4, these results are more dramatic, since the samples were all exposed to
the sunlight for the 7 days, with the increases in size being 7 to 20 fold, and the smallest
particles now representing only 30 to 40 % of the total.
For the data in Table 5, the colloidal silver was left in contact with the
environmental water sample for 21 days in sunlight. As can be seen from the table, the
particle sizes have significantly increased (3 orders of magnitude), with a corresponding
drop in the zeta potential.
In Table 6, the samples were left in contact with the water samples instead of the
soil samples for 7 days in the sunlight. The results of these tests show that each water
sample also decreased the zeta potential and increased the particle size.
PROPERTIES OF COLLOIDAL SILVER USED IN TESTING
nm Zeta Pot., mV Total Ag, ppm Ionic Ag, ppm
1.74 -31.7 21.4 9.60
TABLE 1 – DEIONIZED WATER
Particles, nm Zeta Pot., mV Total Ag, ppm Ionic Ag, ppm
Sand None found -20.2 0.00 0.00
NJ Soil None found -1.5 0.00 0.00
PA Soil None found -31.3 0.00 0.00
TABLE 2 â€“ COLLOIDAL SILVER â€“ 15 MIN. CONTACT â€“ 7 DAYS LATER
Particles, nm Zeta Pot., mV Total Ag, ppm Ionic Ag, ppm
Sand 3.53 -20.6 1.14 0.00
NJ Soil 4.35 -22.2 1.57 0.20
PA Soil 8.30 -21.7 1.05 0.20
In a previous paper by F. Key and G. Maass (4), the nature of a colloid was
described as being a suspension of very small particles which are stabilized by having a
diffuse double layer of solution ions around them. The charge acquired by these particles
gives rise to a potential difference (i.e., mutual repulsion) between them that keeps them
separate and stabilizes the colloid. This potential difference is called the Zeta Potential,
and has been described in countless books on electrolytic effects in solutions. When the
colloid is composed of nanoparticles, the task of preventing the agglomeration is not an
As the previous paper pointed out, if the zeta potential is more negative than
-30 mV, then the mutual repulsion between particles is sufficient to keep them separate
and stabilize the colloid. When the zeta potential is between -15 mV and 0 mV, however,
the particles agglomerate and flocculation or precipitation occurs.
In a 1996 report by the Department of the Interior by M. Elimelech and A. E.
Childress (5), it was pointed out that for world average fresh water rivers, the
concentration of common anions and cations across all normal pH ranges is sufficient to
change the zeta potential range from about -10 mV to +5 mV, making agglomeration of
nanoparticles occur. In sea water, the agglomeration would be even more pronounced.
1. This report has demonstrated that silver nanoparticles will grow to
biologically far less active â€œclumpsâ€ even if one dumps 27 liters of 20
ppm colloidal silver on each ton of soil. In practice, this is an
enormously high number which could not be expected to be reached
2. In spite of the number of manufacturers producing silver nanoparticles
or claiming to be silver nanoparticles, because of the low concentrations
in which these products are sold, the total amount which could be
released in any part of the environment would still be expected to be
3. As shown by all the experiments above, nanoparticles do not last as
nanoparticles in nature for very long, but grow to harmless clumps of
4. Silver nanoparticles are not water soluble, and therefore, silver colloids
will not release silver ions into the environment.
Once agglomeration of the silver nanoparticles occurs, the result is simply
silver metal; a harmless metal which has existed in nature from the beginning of our
planet. Most people would not object to finding silver metal on their property.
1. Environ. Sci. & Technol. 2008, 42, p 7025-7026
2. Tony M. Isaacs, www.americanchronicle.com/articles49272 , May 14, 2008
3. Dept. of Agriculture, Handbook 296, 2006
4. F. Key and G. Maass, â€œIons, Atoms and Charged Particlesâ€, available at
5. Zeta Potential of RO Membranes by M. Elimelech and A. E. Childress, contract