About 70% of the daily dietary ingestion or inhalation of silver in people is excreted in the feces within a week; little is found in the urine (Kehoe et al. 1940, Anon. 1990). Animal experiments with radio-silver show that mice, rats, monkeys and dogs excrete 99.6%, 98.4%, 94.4% and 90.4%, respectively, within 2 days of oral administration. Whole body retention of silver after one week is generally less than 1% of the initial dose in animals but rises to about 20% in man. Little, if any, is normally excreted in the urine but administration of calcium EDTA increases urinary excretion (Furchner et al. 1968). About 18% to 19% of a single oral dose of silver acetate was still in a human body 8 to 30 weeks later (East et al. 1980 and Macintyre et al. 1978). This is greater than the amount retained by dogs and most other animals.
Urine samples were taken from six men who had been employed from 7 to 23 years in jewelry handicrafting. Silver levels for 24 hours ranged from 5 to 261 µg/L. A mean value of 27 µg was found after a five-day shift for workers casting with oxyacetylene while the five-day mean was only 5 µg for those using an electromagnetic induction process (Minoia et al. 1987).