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Silver Toxicity - How much is harmful?


    Can Colloidal Silver harm you? Most of the promotional hype says it can't. However, almost anything can be harmful if used in excess. This includes commonly used drugs and even common foods. Potatoes, tomatoes, wheat, mushrooms, and many other common foods contain toxins and/or carcinogens or even mostly harmless substances which can be harmful to susceptible individuals. They don't usually harm us because we limit their consumption to levels to which our body can adapt to, and metabolize.

    The bottom line is that small doses of silver seem harmless for most people while large doses taken in great excess can be toxic, even lethal. So the question is: what constitutes a small safe amount and what constitutes a large potentially harmful amount?

    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.

    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 presumable sublingually and rectally.  Some individuals also have 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 faeces with active biliary excretion. Even inhaled silver is eliminated through the faeces. (63)

    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 10 ppm colloidal silver. This kind of difference makes comparisons rather meaningless. Clearly, better data is needed to offer those using colloidal silver some idea whether they are foolishly poisoning themselves or have little to worry about.

    One individual, Roger Altman Eng.Sc.D., took the task upon himself to find some of the answers to these questions, without support or funding. He made careful measurements of the silver that he consumed and the silver that he excreted in urine, faeces, hair, nails, sweat, etc. From his carefully collected data, we now have an indication of how these processes work. The summary of his data is presented here with permission. A summary of his data can be found in Appendix B. To purchase a complete copy of his report contact him at

    Dr. Altman consumed 2.34 mg. of silver daily for several months then measured the total silver excreted from his body over a 24 hour period.  He concluded that silver is excreted easily from the body, primarily in the urine.  The total silver excreted during this particular measurement period exceeded the amount consumed during that period.  This is accounted for by the variability of the amount of waste (urine, faeces, etc.) eliminated from the body, the amount consumed through food and water, etc.  It does point out that silver is eliminated from the body much more efficiently than we previously thought.  It also may explain why there have been no cases of argyria reported by individuals using low dosage electrocolloidal silver. The colloidal silver that he was using was electrocolloidal silver made by the high voltage DC (180 VDC) process.  

    Dr. Altman also ran a measurement of silver elimination for 100 days following the cessation of silver intake. Initially, most of the silver was eliminated through the urine.  He noted that increasing water intake increased silver elimination through the urine.  After approximately the first month, silver elimination was greater through the faeces than through the urine.  He estimated that by the 100 day mark nearly all of the accumulated silver had been eliminated from his tissues.  

    This is only one set of measurements on one individual.  It is, however, data carefully obtained by a scientifically trained individual using modern analytical tools.  It suggests that a healthy adult can consume approximately 2 mg. of colloidal silver per day without risk. (Using a quality 55mg/Ag Lt. product the amount of 2mg of colloidal silver would be reached by taking 5 ml per day ) This data is insufficient, however, to assume that the same situation will prevail in other individuals.  Someone with kidney disease, for example, may have difficulty eliminating silver and may risk toxicity with prophylactic consumption.

    The available information suggests that silver salts are clearly more toxic than silver proteins or colloidal silver.  It is possible to produce a variety of silver salts and other silver compounds in some manufacturing processes. 

    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 5 ml. of liquid 
  2. One ppm concentration is the same as 1 milligram (mg.) per liter    
    (Example: 10 PPM colloidal silver contains 10 mg of silver in one liter of liquid)
    (Example: One tsp. of 10 PPM colloidal silver contains 50 micrograms of silver)
  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: 0.1 mg per liter ( 0.1 PPM)
  6. The average person consumes approximately 90 mcg. of silver/day in their food 
  7. The estimated dosage of silver required to trigger an anti-infection response (based on anecdotal reports and other data); is believed to be approximately 1 milligram 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 one to six grams of silver, depending on the reference cited. Some references state as high as 50 grams.(1)(62)
  10. The estimated single dose lethal quantity of silver is: Approximately ten grams of silver (56)


    Here are some links to relevant information on silver toxicity.

  1. colsil_iris.htm - EPA - RFD - Silver 
  2. - RAIS - Risk Assessment Toxicity Profile - Silver 
  3. - Guidelines for Drinking Water Quality - Silver


    The best known consequence of over consumption of silver is argyria. Most authorities state that argyria is disfiguring because of the discoloration of the skin but has no other harmful consequences. 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. Upon exposure to strong sunlight, skin of the affected individuals can turn a dark brown or black color. This coloration is permanent. 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.

    We know that argyria has been produced in adults who were given 900 mg of silver orally over a period of one year (1). There are also cases in the literature where 6.0 grams of silver nitrate administered orally and 6.3 grams of silver arsphenamine administered intramuscularly were known to produce argyria. (1) Another study estimated the minimal oral dose for producing argyria to be 25 to 50 grams taken over a 6 month period. (62) A single fatal dose is estimated to be 10 grams, although recovery from larger doses has been reported.  (56).

    Here are some internet links which provide additional information on argyria. Note that the Rosemary Jacobs case is assumed to involve a different form of silver and much higher dosages than the electro-colloidal silver that is in common use today. Still, it is important to be aware that argyria is a risk if the wrong types of silver are used in excessive quantities.

  1. - Dermatology Internet Service - Argyria 
  2. - Rosemary Jacobs Argyria Page 

    Using the most conservative figure, 900 milligrams of silver corresponds to the silver content in 90 liters of 10 PPM colloidal silver, 45 liters of 20 PPM colloidal silver or 30 liters of 30 PPM colloidal silver. Small children and sensitive individuals could presumably be harmed by less. These doses are very large compared to the doses usually consumed by individuals using over the counter health food store colloidal silver products. Even with these quantities, 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 intake.

    We know that dogs died from injections of a type of protein bound silver in dosages ranging from 500 mg to 1.9 grams of silver depending on the dosage and frequency of administration (46). This was equivalent in silver content to giving a 150 pound adult between 150 and 570 liters of 10 PPM colloidal silver, or between 75 and 285 liters of 20 PPM colloidal silver or between 35 and 120 liters of 50 PPM colloidal silver. The 10 gram estimated lethal dose for humans from Goodman and Gillman (56) is equivalent to 1000 liters of 10 PPM colloidal silver.

    In another case (47), an individual ingested an estimated 124 grams of pure silver nitrate over a period of 9 years. She developed argyria and an assortment of neurological symptoms as well. The authors note that the silver tended to complex with sulfur in the ratio of inorganic Ag2S. A moderate presence of silver-sulfur granules were seen in the perineural tissue, in the peripheral nerves and along the elastic fibers and to a lesser extent along the collagenous fibers and in macrophages. These deposits were noted to have an affinity for basal membranes. The neurological manifestations included taste and smell disorders, vertigo and hypesthesia. This report is often used by critics to attribute neurological disorders to silver consumption. For comparisons to be meaningful differences in quantities must be accounted for. 

    It may be helpful to put this in perspective with the quantities of silver that is consumed in the food and drinking water from natural sources. The EPA publishes a reference dose (RFD) for silver which is an estimate of daily exposure to the entire population that is unlikely to be associated with a significant risk of adverse effects over a lifetime. The current RFD for oral silver exposure is 5 micrograms/kg/d with a critical dose estimated at 14 micrograms/kg/d. The maximum contaminant level proposed by the EPA for silver in the drinking water is less than 0.1 mg/L. (less than 0.1 PPM). 

    Based on this RFD, a 150 pound adult should not exceed 350 micrograms/d. If the silver in drinking water meets EPA standards, an average person drinking 2 liters per day will consume less than 200 micrograms of silver. In addition the daily diet may contain about 90 micrograms of silver. (63) 350 micrograms of silver is equivalent to 7 milliliters (1.4 tsp.) of 50 PPM colloidal silver. This is the amount that the EPA standards permit an individual to consume from natural sources. At this rate, one could conceivably consume enough silver in three days to equal the 1 milligram estimate of a minimum effective dose.

    It should be noted here that some in the silver business believe that it is not necessary to exceed the EPA critical dose to obtain antibiotic effects from colloidal silver provided that the colloidal silver is of extremely small particle size.

    Some researchers have suggested that a deficiency of selenium and vitamin E may increase the susceptibility to systemic silver toxicity. It was hypothesized that silver toxicity as manifested by liver necrosis in laboratory rats was due to silver induced inhibition of the synthesis of the seleno-enzyme glutathione peroxidase. Bunyan, et. al. showed that rats supplemented with selenium or vitamin E tolerated a silver exposure of as high as 140 mcg/kg/d. (63)

    It is also necessary to remember that some individuals have allergies to specific metals. Nickel, copper, silver, and other metals have been known to cause allergic reactions. Be certain that you are not allergic to silver before taking colloidal silver.


  1. It appears that healthy adults may be able to take as much as 5 mg.(100ml of a 50mg preparation) of colloidal silver per day without overwhelming the body's elimination mechanisms.  This is not a recommendation.  Additional research needs to be done to test this hypothesis. 
  2. Individuals with kidney disease may be at increased risk for developing silver toxicity.  This is a reasonable assumption since it appears that the kidneys are a major pathway in eliminating silver from the body. 
  3. Drinking extra water increases silver elimination and may reduce silver accumulation and risk of toxicity.   
  4. Liver disease may increase silver toxicity. Silver may interfere with certain metaloenzymes in the liver, especially if there is a deficiency of selenium or vitamin E.  
  5. Taking extra supplements of selenium and vitamin E may reduce an individual's susceptibility to silver toxicity.  This is based on the finding that supplementation decreased liver toxicity in rats and that rats deficient in these nutrients were more susceptible to silver toxicity. 
  6. Some silver salts are no more more toxic than colloidal silver and silver compounds offer many additional variables. 

    Larger doses of silver and more concentrated forms of silver increase risk of toxicity and argyria since they may exceed the body's ability to eliminate the excess silver.  
  7. Risk of silver toxicity or argyria may be reduced by avoiding any silver consumption for a period of three to four months after the completion of a therapeutic regimen. Based on Dr. Altman's experiment, this would give the body time to eliminate much of the stored silver in the body before continuing treatment. 
  8. The risk of silver toxicity and argyria may be reduced if the total cumulative dosage is kept under one gram of silver, especially if large doses are being consumed or there is kidney or liver dysfunction present.

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