"You’re environmentally exposed to extremely small amounts of silver every day. It’s present in very tiny amounts in drinking water, the food supply and even the air you breathe. As a compound, the silver found in the environment is thought to be quite safe. However, the environmental and health risks of silver nanoparticles are not well understood, and ingesting colloidal silver is considered unsafe. The biggest risk associated with chronic exposure to colloidal silver is argyria.
Argyria is a condition that turns the skin a blue-gray color due to a buildup of silver metal particles in the body and skin. Silver deposits can also occur in the intestines, liver, kidneys and other organs. You are most at risk of developing argyria if you’re taking a silver-containing food supplement or work in a job that exposes you to large amounts of silver.
It’s thought that to develop argyria, you would have had to ingest silver compounds over a long period of time. However, the exact amounts and time frame that would put you at risk aren’t known. The real risks of ingesting nanoparticles, which may be present in colloidal silver products, are also unknown. However, given that these particles may more easily pass into your cells and possibly cross the blood-brain barrier, they are considered a probable health risk." 17 March, 2018