Silver is a metal that is known for its use in jewelry and silverware, but in its ionic form it has properties which are hazardous to the environment. Silver ions are very toxic to aquatic organisms and may cause long-term adverse effects in the aquatic environment. Fish and small crustaceans (like water fleas) are particularly sensitive. Growth or reproduction is impaired at silver ion concentrations even below 1 µg/L.
Silver is persistent and, once emitted into the environment, not reversible. To which extent silver is bioavailable, i.e. can be taken up by plants and animals in the environment, depends on many factors like organic matter content, in particular organo-sulfur compounds, pH and content of other metals. There is some concern that widespread use of silver could cause the development of resistant bacteria. There are reasons, therefore, to recommend precaution with regard to uses of silver which are not essentially necessary.
In the past, silver was widely used in photographic applications, but this has been reduced considerably with the switch to digital technique.
In recent years, however, silver is increasingly applied in other areas, for example in medical supplies, in water cooling systems or for drinking water disinfection. But silver is also used in common consumer products: textiles, shoes, refrigerators, toothbrushes, plastic bottles, vacuum cleaner filters, mattresses, cutting boards, etc. The market for these types of products is growing. The reason for this is that silver in ionic form has antibacterial effects.
Products which contain silver for antimicrobial reasons are not always labelled. Terms which indicate this can be for example: “antimicrobial”, “free of bacteria”, “for lasting freshness”, “hygienic protection”, “keeps the natural hygienic balance”, “treated against odour”, “prevents miscolouring”, etc. Unfortunately, some of the products are even commercialised with the label “environmentally friendly”, without any proof to support this.
The use of silver ions in many different consumer products contributes to diffuse spreading into the environment by sewage water and by sewage sludge. The extent to which silver is released and spread in the environment varies between different uses. The environmental impact by for example silver treated textiles through regular washing is certainly higher than by a refrigerator, which gets wiped only seldom and with far less amount of water. But some kind of environmental impact is likely for all silver containing products. It has been questioned whether the benefits of some of the silver treated products outweigh the negative environmental impact they might have.
Silver used as a biocide requires approval
Silver, i.e. all chemical compounds releasing silver or silver ions, is considered a biocidal product that needs authorization if the purpose of the use is to prevent bacterial growth. Silver used as a biocidal product is covered by the provisions of Directive 98/8/EC concerning the placing of biocidal products on the market.
Read more about biocidal products.
Sweden has been assigned being the Rapporteur for several different silver compounds included in the review program of the directive 98/8/EC. The Rapporteur evaluates risks to human health and the environment connected with the use of silver in different types of biocidal products. The results will be presented in an assessment report. The report forms the basis for the decision taken by the European Community regarding whether these silver compounds should be included in Annex I, IA or IB to directive 98/8/EC and thereby may be used as active substances in biocidal products in the future. Parts of this assessment report will be published on the website of the European Commission.
After the decision regarding whether silver should be included, biocidal products containing silver as an active substance will require an approval in Sweden, as in all EU countries, before they can be sold. The Swedish interpretation of the Biocidal Directive is that only chemical products (substances or preparations/mixtures) can be regarded as biocidal products, not articles as such. This may be changed, however, as a result of the ongoing review of the Directive.
Presently, biocidal products which are chemical products and belong to the group of desinfectants, may also be sold in Sweden without authorization. This reflects a transitional period where most desinfectants that already are placed on the market may be marketed until the European evaluation process is finalised.