I've been doing some research on whether CS is safe to ingest and if so how much is safe. In doing so I've turned up some disconcerting information about CS products. Essentially, laboratory tests show some products aren't what they seem.
The short story is that there are 3 different types of silver that are all marketed as "collodial silver": ionic silver, silver protein and true colloidal silver. For the purposes of reproducing the results in the study (disinfecting the surface of meat) we want ionic silver such as the product used in the study ASAP Collodial Silver 20 ppm.
When ingested the silver ions bind with chloride and are eliminated from the body.
The product used by the OP, Natural Path Silver Wings 500 ppm may be suspect. The laboratory analysis of that manufacturers Silver Wings 250 ppm product was determined by testing to be of the silver protein type which may not be safe to use for our purposes. The label on the Silver Wings 500 ppm product the OP used explicitly states it does not contain protein which should mean it isn't the silver protein type but I'm suspicious especially given the price. Correction - The label only says it doesn't contain gelatin or animal by-products. A non-animal based protein could be used.
Following is some of what can be found at http://www.silver-colloids.com/Reports/reports.html#CompTable
There are three distinctly different types of silver that are labeled and sold on the market as “colloidal silver”; they are ionic silver, silver protein, and true colloidal silver. Consumers seeking true colloidal silver are often at a disadvantage because each of these products represents themselves as colloidal silver.
Ionic Silver Solutions
The vast majority of products labeled and sold as colloidal silver fall into this category due to the low degree of manufacturing complexity and resulting low cost of production. The silver content in these products consists of both silver ions and silver particles. Typically, 90% of the silver content is in the form of ionic silver and the remaining 10% of the silver content is in the form of silver particles.
Ionic silver is not without merit. Ionic silver is a strong anti microbial and serves well in situations where chloride is not present. When chloride is present (inside the human body), the silver particle content will survive to produce benefit.
Ionic silver products, when taken according to the manufacturers recommended dosage, will not cause argyria, a condition that causes the skin to turn blue-gray.
From "The Truth About Ionic Silver"
Silver chloride is a compound that is formed when silver ions combine with chloride ions. It is an insoluble compound which means once it is formed in the human body, it does not dissolve. Silver ions and chloride ions have such a strong attraction for each other that it is virtually impossible to keep them apart. Once they find each other, they form the silver chloride compound. All ionic silver will turn into silver chloride once inside the body because of the readily available supply of chloride ions in many different forms.
Silver chloride is an insoluble salt that does not dissolve inside the body once it has formed. Silver chloride is eliminated by the kidneys and expelled through the urine. The authors believe that only the portion of silver content contained in the particles will remain effective in the body.
Bioavailability of Ionic Silver
Promotional claims made for ionic silver products describe it as having high bioavailability. Nothing could be farther from the truth. The Merck Manual makes it clear that bioavailability is the amount of unchanged drug that reaches the systemic circulation. To be bioavailable the substance being ingested must attain systemic circulation unchanged in form. Because silver ions are highly reactive they quickly form compounds in the body and therefore cannot remain unchanged. While it is the highly reactive nature of silver ions that provides its antimicrobial properties, it also causes the rapid formation of compounds and prevents the continued existence of silver ions inside the human body. Because silver ions cannot exist inside the human body the bioavailability is virtually nonexistent. Silver compounds such as silver chloride in the blood stream provide no meaningful antimicrobial properties.
Silver protein products are the second most prevalent type of so-called colloidal silver products on the market. These products consist of a combination of metallic silver particles and a protein binder, and can easily be produced by simply adding water to silver protein powder sold by various chemical companies.
Most products claiming to be high concentrations of colloidal silver (typically in the range of 30 to 20,000 ppm) are in fact silver protein colloids. While some of these products are labeled as Silver Protein or Mild Silver Protein , many such products are simply labeled as colloidal silver and the word protein does not appear anywhere on the label or in the product advertising literature.
Due to the high concentration of large silver particles, silver protein products are known to cause argyria, a condition that causes the skin to turn blue-gray. These and other dangers associated with silver protein are described in About Silver Protein Products.
Adding protein to colloidal silver is also potentially unsafe because of bacteria, according to Professor Ronald Gibbs who discussed this fact in his booklet " Silver Colloids". He found "mild silver protein" products that had live bacteria growing on the protein.
True Colloidal Silver
True colloidal silver products are the least prevalent type of colloidal silver on the market due to high degree of manufacturing complexity and the resulting high cost of production.
Due to the very low concentration of ionic silver and small particle size, true silver colloids do not cause argyria, a condition that causes the skin to turn blue-gray.