Despite being a heavy metal, according to the periodic table, silver is the leader among the safest bactericides. Overexposure to silver may result in argyria, the condition when skin turns bluish or grey-blue color with no other significant side effects. However, to reach this effect one should intake silver compounds literally from spoons, which is not the healthiest option.
Silver may be found in various forms. The most inactive of them is its metal state. A silver spoon may indeed cause a slight bactericidal effect in a cup of water if exposed during a long period of time. Literally, each bacteria should come in contact with the silver surface.
The most active form of silver is its ionic form. The silver ion (Ag+) shows a bactericide effect starting from 10 mg/L. It is not stable and is easily decomposed when exposed to light and a micro presence of chlorides. It also precipitates when in contact with many other metals and materials. To stabilize silver in its ionic form we can choose two ways: produce a silver colloid or force an ion-exchange.
Silver nanocrystals have a bactericidal effect yet are chemically-stable. By adding stabilizers, for example, surfactants, we don't let them fall out. This is exactly how we get colloid silver, a popular biologically active supplement.
The second way of ionic silver stabilization is to impregnate it with a special type of sorbent. Then silver will be allocated in water with the required speed rate and in accordance with the MCL* requirements, enough to prevent the bacterial growth. This is the way AqualenTM works in Aquaphor filters.
With time we need different drugs, while the effect of silver is stable. In the post-antibiotic era, it may serve us the best remedy, which can save humanity when we find ourselves mired in a trap of ubiquitous antibiotics.
We will continue this topic and discuss why some countries have banned using silver as a bactericide for drinking water and which alternatives can be used instead.
* Maximum contaminant level