British advisors call for government to obtain data on nanosilver in consumer products
The Advisory Committee on Hazardous Substances (ACHS) to the United Kingdom's Department of Environment, Food and Rural Affairs (Defra) last week released a "Report on Nanosilver", recommending that government bodies fund a thorough review of the hazard and exposure of silver nanoparticles as an immediate priority. This should include the identification and formation of an inventory of consumer products containing nanosilver.
Background
The paper follows a request from Defra at its 32nd meeting in March 2009 for the Committee to provide guidance on nanosilver. Specifically the Committee were invited to:
i) Review information and studies on the environmental exposure and effects of nanoparticulate silver;
ii) Comment on known or predicted environmental exposure levels and whether these present a human health or environmental risk;
iii) Comment on the nature of appropriate measures to minimise risks, if these are felt to be necessary at this point in time;
iv) Consider what action should be taken to further develop our understanding in this area.
Following discussions at meetings held in March, June and September, ACHS have now released a report which addresses objectives i), ii) and iv) of the above, with a focus on environmental exposure and hazard rather than human health. Risk management issues (iii) have not been discussed due to lack of available information.
Key findings
The report states that, '[i]n addition to known hazards from silver, there is now evidence that there is likely to be wide exposure to low concentrations of nanosilver in the environment'. The Committee highlighted that, of all the consumer products on the market claiming to contain nanomaterials, the greatest number of those use silver nanoparticles. Nanosilver is currently used in consumer products such as cosmetics, fabrics, toothpaste, toothbrushes, kitchen surfaces, bandages, medical equipment and other products and, the committee added, it has been shown to be released from commercially available products.
The report notes that, due to lack of knowledge, the nature of the environmental risk associated with the widespread use of nanosilver products is at present poorly characterised. However, the Committee suggests that the 'likely wide use of consumer products using nanosilver as an antibacterial agent suggests wide environmental exposure. Available data suggests that the most sensitive species to nanosilver so far tested are likely to be invertebrates and unicellular organisms such as bacteria. Higher organisms such as fish, and also humans, may be less sensitive'.
The Committee also looked at the question of whether there are direct problems associated with silver nanoparticles and, although concluding that the available data on this issue cannot be easily rationalised, it was highlighted that ‘there are indications that toxicity is apparent in the nanosilver form and that there is a specific 'nano-effect' '.
Conclusions & Recommendations
The Committee concluded that, although 'a good deal of information is now available on hazard and some on exposure…it is not possible to fully rationalise often disparate (eco)toxicology results'.
As a result of the uncertainties identified, the Committee said that 'further knowledge on both hazard and exposure is urgently required', calling for funding of the following immediate priorities:
(i) Development of methods to quantify nanosilver in the environment;
(ii) Understanding fate and behaviour processes (transport and persistence) in the environment;
(iii) Understanding biological effects (bioaccumulation, toxicity) under realistic conditions.
Specifically, the Committee suggests that government bodies should immediately fund a thorough review of literature and research in this area.
In addition, the Committee concluded that '[a] further immediate research objective should be a critical review identification and inventory of uses and products containing nanosilver, amounts within products and their likely release rates.' Finally, the Committee also called for immediate funding of research to identify partitioning of nanosilver between different environmental compartments.
Click here to read the "Report on nanosilver" in full.
Source: Defra