The Environmental Risks of Silver in Clothes

Conference poster, 2011

Water treatment companies and other actors in Sweden are concerned over the potential contamination of the waste water sludge due to silver emissions originating from antibacterial applications, such as clothes treated with silver in order to reduce odour. Silver is a compound which is known for its toxicity to several organisms. Hence, increased silver concentration in sludge may therefore prevent the sludge from being used as fertilizer on agricultural land, hence preventing the recycling of nutrients. Therefore, an environmental risk assessment of silver in clothes was conducted for the case of the waste water treatment plant Ryaverket in Gothenburg. Emissions of silver from washing as function of consumption of silver-containing clothes was estimated, the fate of silver in waste water treatment plants and soil was studied, and finally a review was made regarding silver toxicity to soil organisms. The potential concentration of silver in sludge and soil was estimated and benchmarked against different guideline values. The risk assessment reveals a very large variation in silver concentration in clothes, ranging from 0.003 mg/kg up to 1400 mg/kg. This wide range of about six orders of magnitude of course affects the potential concentration of silver in sludge and soil. If silver concentrations close to 1400 mg/kg are to be used in clothes, the current silver concentration in the sludge from Ryaverket could easily become doubled, and if that sludge was to be applied on soil, the silver may accumulate and cause long-term damage to soil ecosystems. However, if silver concentrations close to 0.003 mg/kg are to be used in clothes, it would not constitute a risk to sludge or soil considering the low amounts of silver. Also, the future consumption of silver-containing clothes may vary and will have a significant effect on the results. The recommendation based on this study is either to limit silver concentration in clothes or the consumption of silver-containing clothes if environmental impacts are to be avoided.