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US Government Sites on Silver Safety
Environmental Protection Agency - Reference Dose (RfD) for Silver
The Environmental Protection Agency's Integrated Risk Information System (I.R.I.S.) on Silver provides what is called the Reference Dose (RfD) for recommended limits on daily oral intake of silver. It is the most definitive and concise US government guideline on safe intakes levels for silver. It is at the following link:
• EPA - Integrated Risk Information System - RfD - Silver
The Reference Dose (RfD) that it describes is the guideline that all other EPA agencies, including those that set the drinking water standards, refer to as the most authoritative guideline.
In reading the document, note that the RfD that is represented as 5E-3 mg/kg/day should be read as follows: 5 to the exponent of minus 3 (0.001) = 0.005 milligrams per kilogram of body weight per day.
What this means is: 5mcg of silver per kg of body weight per day. In other words, 5mcg/kg/day.
The EPA's I.R.I.S. on Silver states:
"The critical effect in humans ingesting silver is argyria, a medically benign but permanent bluish-gray discoloration of the skin. Argyria results from the deposition of silver in the dermis and also from silver-induced production of melanin. Although silver has been shown to be uniformly deposited in exposed and unexposed areas, the increased pigmentation becomes more pronounced in areas exposed to sunlight due to photoactivated reduction of the metal. Although the deposition of silver is permanent, it is not associated with any adverse health effects. No pathologic changes or inflammatory reactions have been shown to result from silver deposition."
"Argyria, the critical effect upon which the RfD for silver is based, occurs at levels of exposure much lower than those levels associated with other effects of silver."
Agency for Toxic Substances and Disease Registry - Silver
The Agency for Toxic Substances and Disease Registry (ATSDR) on Silver is the US government's most extensive compilation if data on silver safety and toxicity. It is at the following link:
• ATSDR - Toxicological Profile for Silver
The ATSDR on Silver states:
"Exposure to high levels of silver for a long period of time may result in a condition called argyria, a blue-gray discoloration of the skin and other body tissues. Lower-level exposures to silver may also cause silver to be deposited in the skin and other parts of the body; however, this is not known to be harmful. Argyria is a permanent effect, but it appears to be a cosmetic problem that may not be otherwise harmful to health."
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