Then again I have no idea what the exposure level would be for the average miner. I seem to remember reading something about the huge ratio of ore that must be mined to retrieve a small amount of silver. If I remember correctly, it was tonnes to ounces. If any of you know, please tell me. He noted that while they are widely used in Japan, there have only been ten reported cases of argyria from their use between 1973 and the time that he wrote his article in 1987.
Silver is employed to keep the coating thinner.
The mean silver content of its coating is 0.1 mg per pill. I assume that silver means metallic silver, but I do not know for sure. I will investigate. If anyone reading this has further information, please let me know. The author also said that one Japanese writer had previously calculated that the minimal oral dose of silver that will cause argyria at 90 grams.