Hello silver-list! Here's the next installment on interesting sites and info I came across while doing a web search on "argyria."
The British Columbia Ministry of Environment, Lands & Parks has placed a number of Ambient Water Quality Criteria documents on their web site. The URL for the report on silver standards is: http://www.env.gov.bc.ca/epd/cpr/criteria/awqcfs.html This report has some very interesting things to say. It is sometimes confusing, and there are a few things that might even be frightening for us if we don't keep in mind what they're talking about and why. What BC's scientists reveal is that silver is extremely toxic to microscopic organisms and larval forms of aquatic animals. The report gives the miniscule amount of silver they deem maximum safe levels for aquatic life -- 3 micrograms per liter in hard water or seawater, and .1 micrograms per liter for soft fresh water. They state that "Criteria are set to protect the most sensitive lifestage of the most sensitive species." The whole orientation of the report is that silver is very bad for the same sort of little buggers we're *hoping* to kill off! So you have to keep that context in mind as you read the rest. They don't recommend separate drinking water standards because the aquatic life standards are far more stringent. They even recount that the 50 microgram per liter drinking water standard formerly used by Health and Welfare Canada was scrapped in 1989, "... as the value was very conservative and had no defensible, scientific basis." This all makes some sense when you read the section on "Application of Criteria for Aquatic Life." Their rundown of the effects of silver on various organisms and biological systems suggest that an awful lot is already known. They plainly acknowledge the features of silver that make it such a good anti-bacterial agent. Let me quote the most interesting section here: > Silver is a disinfectant for non-spore forming bacteria at > concentrations about 1000 times lower than the levels at which it > is toxic to mammalian life. This extreme mammalian-to-bacterial > toxicity differential is the definition of an oligodynamic > material. The low concentration necessary for oligodynamic > activity allows silver or one of its insoluble salts to be used > indefinitely in contact with sterile liquids without silver levels > building up to concentrations harmful to people. > The biological effects of silver are apparently due to reversible > bonds with enzymes and other active molecules on the surface of > cells. Due to its sulphydryl binding propensity, biologically > available silver disrupts membranes, disables proteins and inhibits > enzymes. The ionic form of silver is necessary for biological > activity and the lipid phase of the membrane appears to be > important in adsorbing silver ions to living cells. The active > sites on enzymes which are affected by silver are apparently the > electron-rich functional groups such as-SH groups. > Silver combines with plasma proteins, is removed by the liver and > over 90% is eliminated in the bile; most of this in the feces with > very little in the urine. That silver which is not excreted is > deposited in the skin and mucous tissues. Tissue deposition of > silver results from precipitation of insoluble salts such as > silver chloride and silver phosphate. They go on to describe argyria in some detail, with no mention that the exposure levels required to bring it about are many thousands of times greater than those being discussed, therefore rendering the discussion interesting, but irrelevant. They do note, rather explicitly, that: > Silver has low toxicity to vertebrate animals and is eliminated > rapidly when ingested orally. It is not a cumulative toxin. So here we have a government report based on a review of the available scientific literature on the effects and toxicity of silver on various organisms. The study results in ambient silver standards many times lower than would be necessary to protect people, wildlife, and livestock. The authors recount the very features of silver that make it effective in killing bacteria, fungus, mold, and other simple creatures. Their discussion of argyria fails to provide enough context to even justify it's inclusion. They provide no clue what levels of intake would be required, and seemingly conclude that it is not an important consideration in terms of ambient water quality. So this report tells us a lot of things we already know. Silver is good for killing little bugs. Argyria happens, but not, it seems, with the kind of preparations we are making. Be well, Mike [Mike Devour, Citizen, Patriot, Libertarian] [[email protected] ] [Speaking only for myself... ]
