Exposure to silver nanoparticles: update of knowledge
Silver nanoparticles are used in various industrial applications, in sectors such as food (additives, food packaging, internal linings of refrigerators), textiles (clothing and bedding) and cosmetic and hygiene products (toothbrushes, hair straighteners, disinfectant sprays, etc.). They are mainly used for their antibacterial and antifungal properties. However, it is still proving very difficult to obtain an inventory referencing all products containing silver nanoparticles in France and elsewhere in the world. In 2011, ANSES received a formal request to update knowledge on the assessment of health and environmental risks associated with exposure to silver nanoparticles. In the Opinion it is publishing today, the Agency stresses the research that has been carried out to examine the potential health and environmental effects of silver nanoparticles but notes that this is still insufficient to allow the health risks to be assessed. Nevertheless, based on the conclusions of its Opinion of April 2014 on the risks associated with manufactured nanomaterials, ANSES recommends limiting the marketing of products containing silver nanoparticlesto applications whose advantages have been clearly demonstrated.
Silver nanoparticles in aggregate, agglomerated or even colloidal form, are used in a large number of industrial applications, especially in sectors such as food (additives, food packaging, internal linings of refrigerators, etc.), textiles (clothing and bedding) and cosmetic and hygiene products (toothbrushes, hair straighteners, disinfectant sprays, etc.).
It is claimed that silver nanoparticles are incorporated in items available on the market for primarily antibacterial and antifungal purposes, and questions are regularly raised about their impact on health, as well as the possible consequence of their dispersal in the environment.
In response to two reports published on this subject in 2009 and 2010, respectively by ANSES and its German counterpart (BfR), the Agency received a formal request in 2011 to update knowledge on the assessment of the health and environmental risks associated with exposure to silver nanoparticles, taking into account the many scientific articles published since 2010 assessing the toxicity of these nanoparticles.
The expert appraisal that it is publishing today includes new knowledge about all the exposure routes for silver nanoparticles, as well as their antibacterial activity and potential resistance of bacteria to these nanoparticles.
The Agency emphasises that the recently published toxicology research is often contradictory, making it difficult even to this day to estimate the potentially hazardous nature of silver nanoparticles. It is in fact impossible, today, to rule, for example, on their reprotoxic, genotoxic or neurotoxic nature.
The ever increasing number of ecotoxicity studies show biological effects on all the aquatic and terrestrial organisms studied (mortality, growth inhibition, genotoxicity, reproductive toxicity, etc.).
The Agency’s recommendations
The expert appraisal conducted by the Agency on silver nanoparticles demonstrates the many difficulties already encountered during its assessment of the risks associated with nanomaterials. In this regard, ANSES reiterates the recommendations issued in its Opinion of 15 April 2014 on the assessment of the risks associated with nanomaterials - issues and update of current knowledge, which called for a strengthening of the regulatory framework for manufactured nanomaterials, in order to better characterise each substance and its uses, taking into account the entire lifecycle of products.
Concerning silver nanoparticles in particular, ANSES recommends:
- encouraging research work in the fields of physico-chemical characterisation, exposure assessment, toxicology and ecotoxicology, assessment of antibacterial effectiveness and bacterial resistance;
- enhancing the traceability of data and consumer information on products containing silver nanoparticles. The Agency stresses that this traceability cannot be achieved solely by means of the compulsory reporting in the R-Nano database.
The Agency also reiterates that silver is not on the list of minerals that can be used for the manufacture of food supplements, whether or not in nanoparticle form. Given the presence of nano-silver in food supplements on the market, including those distributed via e-commerce, the Agency recommends enhancing consumer information and control of the distribution of such products containing silver nanoparticles.
Lastly, ANSES recommends that the use of silver nanoparticles (production, processing, utilisation) be limited to applications whose advantages have been clearly demonstrated, and whose benefits to human health outweigh the risks for the environment.