What about toxicity? Can colloidal silver be harmful?
Silver is a metal. Ingestion of excessive amounts of metals of all types has been proven to be harmful. On the other hand, silver is also a nutrient that the body needs for healthy growth and repair. Therefore the questions really are: How much colloidal silver is needed to gain a benefit due its antimicrobial properties, and how much is too much?
First, let's examine how much silver would be needed to produce a toxic condition. It is important to recognize that everyone may have their own unique level at which any nutrient causes a toxic reaction. The most commonly discussed side effect from excessive intake of elemental silver is a condition known as "argyria". "With argyria, silver is taken internally in excess and the excess is deposited in the skin, organs, and other tissues. This causes the skin to turn a gray or bluish gray color. In addition to argyria, the intake of very large doses (far in excess of the amount that causes discoloration of the skin) of silver can cause neurological damage, organ damage, and arteriosclerosis."
The quotes above are from the publication, Colloidal Silver: Medical Uses, Toxicology, & Manufacturing. It is obvious that everyone would want to limit the intake of colloidal silver to be well below any level that could cause argyria, or any other problem. The chapter, "Silver Toxicity - How Much is Harmful" attempts to provide documentation for an answer:
"Unfortunately, there is no definitive answer to that question. There is, however, some information available that can serve as clues or points of reference from which a 'guess' can be made. This is not intended to be construed as medical advice or recommendations for usage, but as correlative information for academic and research purposes."
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"In the various promotional documents on colloidal silver, a theory is often presented that 'true' colloidal silver is non-toxic and that only the older silver proteins and silver salts are toxic. It is true that nearly all of the toxicological data is on silver salts and silver proteins with much higher silver content than current electrocolloidal products. It is also true that colloidal silver, silver salts, and silver proteins cannot be assumed to produce the same results or have the same toxicities. It is also true that I have been unable to find any documentation of a single case of argyria produced from the consumption of low concentration electrocolloidal silver. It is my assumption, however, that the low dose electrocolloidal silver could cause argyria if used in sufficiently excessive quantities."
"Two very important factors are the total accumulated dose of silver and how quickly it was consumed. The rate of consumption is probably more important than the total quantity because there is an excretion process. If the intake exceeds the body's ability to eliminate the silver, it accumulates in the tissues. An estimation of the body's ability to eliminate silver is then critical to understanding what dosage is toxic."
"It appears that colloidal silver is absorbed orally through the GI tract, through the nasal mucosa, and presumably sublingually and rectally. Some individuals have also reported injecting colloidal silver."
"None of the old medical literature that I was able to find gave a satisfactory assessment of the absorption, retention, and excretion of colloidal silver. The old literature suggested that silver is eliminated primarily through the feces with active biliary excretion. Even inhaled silver is eliminated through the feces."
"The silver products that were used in the early twentieth century were mostly silver proteins rather than colloidal silver and the silver content was much higher, 10% to 30% by weight rather than the 0.001% silver content of 10ppm colloidal silver. This kind of difference makes comparisons rather meaningless."
Note: Mild Silver Protein is currently manufactured under the brand name "Argyrol S.S. 10%". Argyrol is sold as a very potent and caustic antiseptic. This 10% stabilized solution of mild silver protein contains 20mg/ml of elemental silver. This concentration equals 2% silver content. In contrast, modern electrocolloidal silver solutions containing 10 parts per million equal 0.01mg/ml, which is 0.001%. In other words, a colloidal silver solution at 10 ppm is only 1/2000th as concentrated as the 20mg/ml Argyrol.
The article continues, "For someone using colloidal silver, it is important to estimate the total number of milligrams of silver in a dose and the total number of milligrams consumed over the course of treatment.
"Here is a summary of reference points to work from:
1. One tsp.contains 5ml of liquid.
2. One ppm concentration is the same as 1 milligram (mg.) per liter. (That is, 0.001mg/ml, which is the same as 1.0 microgram/ml. Therefore, 10 ppm equals 10mcg/ml.)
Example: 10 ppm colloidal silver contains 10mg of silver in one liter of liquid.
Example: One tsp. of 10 ppm colloidal silver contains 50 micrograms of silver (That is, 0.050mg.)
3. The EPA reference dose for a 160 pound adult (the average amount consumed per day in food and water): 364 micrograms per day.
4. The EPA critical dose for a 160 pound adult (the amount that should not be exceeded in daily consumption): 1.09 milligrams per day.
5. The EPA proposed limit for silver in drinking water is: 0.1mg per liter (0.1ppm)
6. The average person consumes approximately 90mcg of silver per day in their food.
7. The estimated dosage of silver required to trigger an anti-infective response (based on anecdotal reports and other data) is believed to be approximately 1milligram of silver.
8. References (8) and (70) state that the estimated total dosage of silver required to treat serious infections such as LYME disease is: approximately 18 to 90 milligrams of silver over the period of one month.
9. The estimated accumulated dosage required to produce argyria is: approximately 1 to 6 grams grams of silver, depending on the reference cited. Some references state as high as 50 grams. (1)(62)"
The references cited in the quotes above are as follows:
(1) ARGYRIA, The Pharmacology of Silver, William R. Hill, M.D. & Donald M. Pilsbury, M.A., M.D., The Willams & Wilkins Company, 1939.
(62) "A Contribution to the pathology of generalized argyria with a discussion of the fate of silver in the human body", Gettler, A. O., et. al., Am J Pathol 1927; 3:631-52.
(70) Farber, Paul M., N.D., D.C., PhD., The Micro Silver Bullet, 1995, ISBN 1-887742-00-X.
Further information on the toxicity of silver is found in the article, "Evaluating Colloidal Silver, Based on EPA Guidelines, published on http://silverdata.com. This article confirms and summarizes the data quoted above:
"One teaspoon (5ml) of 5 ppm colloidal silver contains 25 micrograms of silver, or 0.025 milligrams of silver. Six teaspoons, the equivalent of one fluid ounce (30ml at 5ppm), therefore contains 0.15 milligrams of silver. The EPA's critical dose for a 160 lb. adult is 1.09 milligrams daily. Taking one ounce of colloidal silver daily, according to EPA guidelines, is well below the critical intake for the development of Argyria. Four ouces daily (at 5 ppm) would equal around 0.6 milligrams."
To use the same illustration with a higher concentration of 10 ppm, each teaspoon (5ml) would contain 50 micrograms of silver. In order to exceed the safe dose of 1.09mg per day, according to EPA guidelines, one would need to consume 109ml (at 10 ppm), or 21.8 teaspoons of solution.
"There is a POSSIBILTY of allergic reaction to pure silver. While most allergic reactions apply only to silver alloys, there still remains the minute possibilty of allergic reaction to pure silver. Like most common reactions, cessation of the allergy causing substance results in complete alleviation of symptoms, with no lasting effects. We have never found a suspected case of allergic reaction with pure silver that could be identified."
"Exotic medications: There is a possibility that colloidal silver may interact with rare prescription drugs that have unique hydrochloric acid combinations. We were not able to do any follow up work as of yet, however, it should be noted that this does NOT apply to taking HCL in any form. From the brief data that we gathered, an easy test is to take several drops of clear colloidal silver, and apply to skin. If a grey patch develops on the exposed area that does not rub off, avoid exposure to any type of silver. The stain is not permanent and can be scrubbed off or will fade off in a few days."
Related to the reference above concerning the use of colloidal silver inconjunction with prescription drugs, another warning was found in an article "What is Colloidal Silver" "(C)olloidal silver should not be used along with intravenous EDTA chelation, as silver is a metal and EDTA works by absorbing and removing metals from the blood. For this reason, the two work against each other."
Quoting again from the chapter, "Silver Toxicity - How much is harmful?", we find the following summary: "We know that argyria has been produced in adults who were given 900mg of silver orally over a period of one year" This amount is referenced to the article, "ARGYRIA, The Pharmacology of Silver", William R. Hill, M.D. & Donald M. Pillsbury, M.A., M.D., The Williams & Wilkins Company, 1939.
The chapter continues, "Using the most conservative figure, 900 milligrams of silver corresponds to the silver content in 90 liters of 10 ppm colloidal silver. Small children and sensitive individuals could presumably be harmed by less. Even with these quantities, the risk of toxicity may be reduced by spreading the intake out over a period of time to allow the excretion mechanisms to keep up with the intake."
From the above data we can see that one would need to consume an incredible amount of a colloidal silver solution at 10 ppm to potentially cause argyria. If the consumption of 90 liters was evenly divided over one year this would equal an amount of 246 milliliters every day, for a total of 2.46 milligrams of silver per day. Obviously, this is far in excess of the 5ml per day cited in the example above, yet even this excessive amount may be eliminated faster than the body can retain a toxic amount of elemental silver. In fact, the same article concludes, "It appears that healthy adults may be able to take as much as 2mg of colloidal silver per day without overwhelming the body's elimination mechanisms."
Colloidal Silver: Medical Uses, Toxicology, & Manufacturing also includes an Appendix B: Colloidal Silver Absorption/Excretion Report Summary. This is a summary of a study conducted by Robert Altman, Eng.Sc.D. (firstname.lastname@example.org) "Dr. Altman's conclusions are:
(1) Injestion of properly prepared CS does not result in silver accumulating in the body.
(2) There is no evidence that silver deposits significantly in hair or fingernails and, in fact, the data support the conclusion that after taking more than 2mg of CS per day for several months, silver seems to be purged from the body (mostly through urine) at about the same rate at which it is consumed.
(3) Furthermore, upon terminating CS intake, it appears that as much as half the silver residing in body tissue will be purged through urine and feces (but more and more through feces as time goes on) in less than a month. Even this relatively short residence time could be reduced substantially if several liters of water were consumed daily."