This is a paper by a student. The “Plague of the Living Dead” in the title refers to the possibility of your skin turning bluish (zombie-like) if you consume it regularly over a long period of time. It’s called argyria and it’s very rare.
http://en.wikipedia.org/wiki/Argyria

Amplify’d from serendip.brynmawr.edu
Does colloidal silver really
carry the medicinal cure-all properties it is claimed to have, or is it
just risk without benefit?
Silver has been used for hundreds of years as both a medicine and
preservative by many cultures around the world. The Greeks used silver
vessels to help keep water and other liquids fresh. Pioneers put silver
coins in the wooden water casks to keep the water free from the growth
of bacteria, algae, and other organisms, and placed silver dollars in
milk to keep it fresh.
In the 1940s, the use of colloidal silver in the medical field began to
taper off mainly due to the advent of the modern antibiotics, but also
due to three other reasons. The first was the high cost. Even in the
depression era of the late 1930′s, colloidal silver was reported to
have been sold for as much as $200 per ounce (in present day dollars.)
The second reason was that many of the silver products available at the
time contained toxic forms of silver salts or very large particles of
silver related to the available technology of the time. The third
reason is that in 1938 the federal Food and Drug Administration
established that from that point forward, only those “drugs” which met
FDA standards could be marketed for medicinal purposes (1).
In 1999, the FDA banned the use of colloidal silver or silver salts in
over-the-counter products. Silver products can and are sold as “dietary
supplements” in health stores only if they make no health claims, but
many advertisers ignore the last restriction and still promote the
benefits of the use of colloidal silver.
Prolonged contact or too much of colloidal silver can result in
argyria, which produces a “gray to gray-black staining of skin and
mucous membranes produced by silver deposition” (3).
From his own bacteriological experiments,
Dr. Henry Crooks supports the use of colloidal silver, claiming that
all known disease-causing organisms die within six minutes of the
ingestion of silver. Medical promoters of the use of colloidal silver
allege that the presence of colloidal silver near a virus, fungus,
bacterium or any single celled pathogen disables its oxygen metabolism
enzyme, or its chemical lung, so to say. Within a few minutes, the
pathogen suffocates and dies and is cleared out of the body by the
immune, lymphatic and elimination systems (5).
People in the medical field against the use of colloidal silver argue
that just because a product effectively kills bacteria in a laboratory
culture does not mean it is as effective in the human body.
There are compelling arguments both for and against the use of
colloidal silver as an alternative to antibiotics. However, very little
research has been done to test the effectiveness of the use of silver
in the human body to fight infections, and the risk of argyria
increases as the number of people using silver increases while the
amount of information known remains constant.Read more at serendip.brynmawr.edu