Maybe I'm remembering incorrectly but once ionic silver enters a cell, it reacts with sulfur or selenium inside the cell forming either silver selenide or silver sulfide. As I recall, BOTH are light sensitive and now not being an ion anymore, they can't get back out. "Infect" enough cells this way and those exposed to light will start taking on a greyish blue color which is permanent (you "smurf" yourself). Given the body replaces itself every 7 years (all cells are regenerated, replacing old cells), if you do this to yourself, once you stop doing it, it could take up to 7 years to lose the "smurf". NOT GOOD!
The simple solution is don't! Only ingest colloidal silver which doesn't do this.
Even using IS for external purposes, you can more quickly turn the spot you've treated blue. Someone here did that a few years back. As I recall it faded over months (it was only the surface few layers of skin infected) but I certainly wouldn't want this.
And I completely agree with Colin (cfnisbet) that most research papers aren't worth the paper they're printed on. A lot of research is done to get research dollars and the most expedient way to convince someone with a fist-full of money that they need to give it to you for further research is to cut corners (though some researchers walk around with their heads up their butts too) and take the expedient way. As Colin says, if you don't ask HARD, revealing questions regarding what the research and results are and how they were really obtained, you're setting yourself up to be duped.
The easier way is to believe whats posted here on the forum as this information has been verified to be correct over a LONG period of time (the forum has been around for a LONG time)... and we're all still here (wink).
There is very little research or information on the web that really pertains to how we make (almost none) and use Colloidal Silver. Oh yeah, there are a lot of Colloidal Silver "used car salesmen" though. Beware!