Ian, my other posting did not address your question on safety of silver 
chloride. Most knowledgeable folks at this site tend to view it as harmless 
though somewhat ineffective. But I know of one authority here in Australia who 
considers it and other similar silver compounds to present a longer term threat 
of kidney failure. The man is Bill Briggs, and he may be contacted at:
 bill-bri...@silvercolloidaustralia.com

This is a controversial topic!