Sometimes, exposure to silver in one form or another can cause a side effect that can be seen with the naked eye. When this occurs, the skin will take on a permanent bluish- or ash-gray hue. This condition, known as argyria, is taken from the word argentus, another name for silver.
Argyria results from silver sequestration in the body. The change in pigmentation is caused by excessive silver ingestion. Similar to tattoos, silver can remain in the body for an extended period without causing a problem.
It has been suggested that AgNPs may act as Trojan horses, entering the cells and then releasing silver ions that damage intracellular functions. Such ions can damage the membrane too.
Argyria can be localized or generalized. Localized is found at the place where the silver entered the skin, while generalized argyria involves a silver-gray coloration in the skin, eyes, or nails. This change in pigmentation may be also found in the internal organs. When silver deposits come in contact with sunlight, a reaction takes place similar to that of old photographic plates. While this cosmetic change may be alarming, it is not really dangerous. Once again, it is important to put things in perspective using reliable sources with scientific data.
How common is this condition?
Orphanet is an informational reference portal for rare diseases, composed of health professionals from roughly forty countries. Inserm, the French National Institute of Health and Medical Research, is the overall coordinator of the project. Funding is provided by Inserm, the French Directorate-General for Health, and the European Commission. As a result, the project does not serve any commercial or for-profit organizations. Its goal is to provide reliable medical information for public wellbeing.
According to Orphanet, argyria is currently a rare disease. By definition, this means it is a disease that affects 1 person in 2,000. There are several reasons why the number of cases of argyria has decreased dramatically. One is that many people became argyric due to exposure to silver salts. Guidelines for when and how to use silver salts have become more precise, resulting in very few cases of overexposure. Also, many cases of argyria resulted from ingestion of homemade silver particles. People are increasingly aware of the dangers associated with DIY silver and are wisely choosing professionally made products. In addition, many people became argyric from medical treatments that have since been discontinued. Lastly, the great majority of argyria cases happened because workers absorbed too much silver while on the job. Tighter global health and safety guidelines for the workplace mean employees are more protected against over-absorption of silver.
If you really research this issue, you will find that in all of human history, there have been very few cases of argyria, and each and every one of them were due to the above causes and/or human irresponsibility.
How dangerous is this condition?
To put it very simply, argyria is not dangerous. Other than the discoloration, research to date shows no significant evidence of clinically negative effects or damage. In fact, the opposite is the case.
One recent example is a study reported in The Bone and Joint Journal in 2013. The article discusses patients who received silver-coated megaprostheses, medical devices “widely used in the reconstruction of large bone defects in revision surgery or following the resection of tumors”. Over a period of seven years (2004-11), thirty-two patients received megaprosthetic implants at two medical centers, one in Austria and one in Germany. Of these thirty-two, seven developed local argyria about twenty-six months after implantation. Tests revealed no neurological symptoms, or was there any renal (kidney) or hepatic (liver) failure. The researchers conclude that while the discoloration of local argyria may not be cosmetically pleasing, the condition is generally benign (harmless).
There is no reliable information that argyria has ever been caused by coated silver nanoparticles. One mechanism by which argyria can occur is when a high amount of silver ions (salts) travels to tissues and skin. Due to particular conditions there, they can precipitate and possibly even form nanoparticles from ions. This a very likely mechanism with a chemical base, but coated nanoparticles do not release enough ions to come even close. Coated nanoparticles are basically chemically neutral and do not interact with tissues.
Once silver ions arrive in peripheral tissues, an environment like glutathione, for example, can reduce silver ions to solid silver nanoparticles.
Colloidal Silver Conclusion 7:While much has been made of argyria, the actual number of cases is quite small. To date, argyria has been shown to be generally harmless, and its occurrence is rare and not at all present in those using coated nanoparticles.
 “About Rare Diseases.” https://www.orpha.net/consor/cgi-bin/Education_AboutRareDiseases.php?lng=EN
 “Argyria Following the Use of Silver-Coated Megaprostheses.”
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