Exposure to silver nanoparticles

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 into items available on the market for primarily antibacterial and antifungal purposes, and questions are regularly raised on their impact on health, as well as on 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 their toxicity.

The expert appraisal that it published in 2015 (PDF) (in French) included new knowledge on all the exposure routes for silver nanoparticles, as well as on their antibacterial activity and the potential resistance of bacteria to them.

The Agency emphasises that the most recent toxicology research is often contradictory, making it difficult today to estimate the potentially hazardous nature of silver nanoparticles. It is in fact currently impossible to rule on their reprotoxicity, genotoxicity or neurotoxicity, for example.

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 illustrates the many difficulties already encountered during its assessment of the risks associated with nanomaterials in general. In this regard, ANSES reiterates the recommendations it made in its Opinion of 15 April 2014 on the assessment of the risks associated with nanomaterials (PDF) (in French). This included the issues surrounding them and an update of current knowledge, calling for a strengthening of the regulatory framework for manufactured nanomaterials in order to better characterise each substance and its uses while 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;
• improving data traceability and consumer information on products containing silver nanoparticles. The Agency stresses that this traceability cannot be achieved solely by means of 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 distributed on the market, including via e-commerce, the Agency also recommends enhancing consumer information and control of the distribution of such products that may contain silver nanoparticles.

Lastly, ANSES recommends that the use of silver nanoparticles (production, processing, use) be limited to applications whose advantages have been clearly demonstrated, and whose benefits to human health outweigh the risks for the environment.