Assessing the Environmental Risks of Silver from Clothes in an Urban Area

The environmental risks from the use of silver-containing clothes ("silver clothes") were assessed for an urban area. First, we evaluated whether the use of silver clothes may cause contamination of wastewater treatment sludge that exceeds certain risk thresholds. Second, we assessed the risk of silver exposure to earthworms from applying the sludge as fertilizer to agricultural land. The most critical parameter was the concentration of silver in silver clothes, for which estimates in the literature vary by more than five orders of magnitude. For concentrations at the high end of that parameter range, there is considerably increased concentration of silver in the sludge, and toxic effects on earthworms even at modest use rates of silver clothes suggest high risk. At the low end, no risks can be expected. The main recommendation from this study is that if silver is used in clothes, the silver concentration must be kept at the lower end of the range applied in this study if risks are to be avoided. This can be done either by design choices of companies, or by regulation. If the function of the applied silver is not maintained at these lower levels, the use of silver clothes should be minimized.