If silver is a naturally occurring substance, is it found in drinking water? At what levels is this this safe?
Federal safety documents provide an answer, along with some additional information about silver.
According to the CDC’s Agency for Toxic Substances & Disease Registry, silver is “an element found naturally in the environment.”
“Silver is used to make jewelry, silverware, electronic equipment, and dental fillings. It is also used to make photographs, in brazing alloys and solders, to disinfect drinking water and water in swimming pools, and as an antibacterial agent.”
Interestingly, silver that has entered the environment “… does not appear to concentrate to a significant extent in aquatic animals.”
The full source document, which is available here, also mentions several EPA statements regarding silver. In reference to drinking water, the document states, “The EPA recommends that the concentration of silver in drinking water not exceed 0.10 milligrams per liter of water (0.10 mg/L) because of the skin discoloration that may occur.”
0.10 mg/L translates approximately into 0.1 ppm (parts per million.) Note that this recommendation is for drinking water, which is consumed on a daily basis in a relatively high volume. In comparison, silver supplements are typically taken in small amounts (teaspoons) on an intermittent basis.
For additional information about silver in naturally occurring water sources, see Silver Levels in the Environment.