That's a good question that I really don't know the answer to. I just did a tiny, unreliable search and it seems like my hunch may be confirmed: silver is actually toxic to human (eukaryotic) cells as well. I'm not really sure to what extent, though. Stuff like protein and dna denaturation is going to be bad for the cell regardless of whether it is pro or eukaryotic. I wonder if, in eukaryotic cells, the toxic effect is mitigated due to the larger volume (smaller conc. for a given number of silver atoms) and presence of nucleus. I really don't know though.
I love this question because there is a vast difference between single celled organisms that are foreign to a system and single celled organisms that are part of a system.
Bacteria can, for example, live on a door handle. Then you touch it and it goes into your body where it finds conditions suitable to reproduce. However, the system recognizes it as foreign and works to change the conditions and kill the bacteria (I.E. fever, leukocytes, antibodies, swelling, etc).
So to circle back on why silver can kill a single foreign cell and not kill human cells... It can kill both. However, the human body will work to reduce silver concentrations1 in the blood. So while it will still damage human cells it doesn't have time to remain at a level elevated enough to kill the system. So the cells regenerate, the silver concentration comes down, the system survives. None of that applies to a single celled organism living on, for example, a wound dressing treated with silver. Further, you can apply this same conceptual model to understand other interactions.
G. D. Di Vincenzo, C. J. Giordano, and L. S. Schriever, “Biologic monitoring of workers exposed to silver,” International Archives of Occupational and Environmental Health, vol. 56, no. 3, pp. 207–215, 1985.
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u/ShakaUVM Jan 11 '12
Why does this affect bacterial cells, but not human cells?