BIOLOGIC MONITORING OF WORKERS EXPOSED TO SILVER

The smelting and refining of silver and the preparation of silver salts for use of photosensitized products can lead to occupational exposures to silver. Our objectives in this study were to determine the absorption and elimination of silver by workers exposed to different species of silver, to estimate the body burden of silver and to relate these findings to the potential development of argyria. Workers potentially exposed to silver (n = 37) and a similar number of controls (n = 35) participated in this study. Blood, urine, feces and hair samples were collected and were analyzed for total silver cotent by atomic absorption spectroscopy. The mean concentration of silver in the blood, urine and feces of silver workers was 0.011 .mu.g/ml, < 0.005 .mu.g/g and 15 .mu.g/g, respectively; and of controls was < 0.005 .mu.g/ml, < 0.005 .mu.g/g and 1.5 .mu.g/g, respectively. The concentration of silver in hair was markedly higher for the silver workers than for controls (130 .+-. 160 vs 0.57 .+-. 0.56 .mu.g/g, respectively). The importance of these latter findings was questionable since airbone particles of silver can bind to hair and lead to apparent high values. Since silver is eliminated predominantly in the feces, fecal measurements were used as an index of exposure and as a means of calculating body burdens. Human exposure to metallic silver at the TLV (0.1 mg/m3) is expected to lead to a fecal excretion of about 1 mg of silver per day. Silver workers excreted an average of 0.3 mg of silver per day in feces, corresponding to a time weighted average workplace exposure of about 0.03 mg/m3. The incremental body burden of silver for silver workers and controls (the latter was derived entirely from food consumption) was calculated to be 14 and 2 .mu.g/kg of body weight, respectively. Our findings indicate that generalized argyria is unlikely to occur in workers exposed to silver at the above exposure levels.