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Posted: Aug 25, 2011

Danish EPA publishes survey on nanomaterials risks

(Nanowerk News) The Danish Environmental Protection Agency (DEPA) has initiated the study "Survey on basic knowledge about exposure and potential environmental and health risks for selected nanomaterials". The objective of the study is to provide an overview of the applications of the most commonly used or widespread nanomaterials and to identify areas most likely to have health or environmental problems associated with their use.
There is no single source of information that provides an overview of the use of nanomaterials and products in Denmark or in the EU for that matter. Pieces of information are, however, available from databases and previous studies initiated by DEPA. This information has in this project been reviewed together with results from other studies carried out in the Nordic countries and including estimates on relevant consumer applications and uses of the selected nanomaterials. A considerable part of the nanomaterial-containingproducts are found to be sold from web shops in Denmark and abroad but an increasing part is sold from ordinary shops.
A limited industry survey on the industrial use of the selected nanomaterials in Denmark has been conducted. The objective of this survey was to confirm the use of the nanomaterials in question in Denmark, and to develop a rough estimate of the consumption.
The survey was carried out among identified actors dominating the markets for the selected nanomaterials and their typical applications. The relevant actors were asked about the uses and the amounts of the nanomaterials. Focus for the survey was on obtaining information for the most dominant field of application and not to cover all different use areas.
The outcome of our survey can be summarized as follows:
  • Titanum dioxide, nanoclay and silicium dioxide are all materials used in most significant quantities in Denmark.
  • The use of nanosilver has not been confirmed, but indications exist that some products/brands may contain nanosilver.
  • The use of cerium dioxide has not been confirmed either. It is not used by leading marked actors in Denmark.
  • No information was available on fullerenes and zero-valent iron.
    A profile for each of the selected materials was then developed. For each material the focus has been on the general characteristics and manufacture of the nanomaterials, their current uses (mainly focussed at consumer products), and hazard profiles (ecotoxicity and human toxicity). Furthermore the profiles include sections discussing relevant exposures from consumer products and considerations regarding the related risk.
    Each nanomaterial profile is summarised in a 'summary sheet' containing the key findings and also emphasising areas where information is lacking. The general picture is that the specific knowledge base is limited and that more information is needed for sufficient characterisation of the nanomaterials and for illustration of the relevant (eco)toxicological endpoints. In addition more information is required with regard to fate, behaviour and kinetics of the different nanoparticles and crucial to the assessment of the relevant risks is an agreed methodology for risk assessment.
    Conclusive risk assessments were therefore not possible to develop within the framework of the present project. Based on the reviewed literature the seven selected nanomaterials were not found to exhibit new and completely unknown risks to the consumer or to the environment in the current application. Products in the form of liquids or free particles are expected to give rise to the highest exposures in the environment and to humans, particularly those liquids that are intended to come in direct contact with the body, and the potential risk is likely to increase with increased exposure. However, as the applicability of the existing exposure and risk assessment methodology has been chal11 lenged in relation to nanomaterials, there are still areas that need to be explored - especially for engineered nanomaterials.
    A key question in relation to risk and safety assessment of nanomaterials as raised in Stone et al. (2010) is to which extent the existing knowledge base about toxicity and risk related to the bulk counterparts can be used in the evaluation of the nanomaterials. In other words, it is the question of whether the risk information can be scaled from bulk substances to the nano-form taking the size of the nanoparticles into account or whether it is the small size that triggers the nano-specific behaviour and effects.
    Based on the reviewed literature there are some indications that scaling of toxicity could be relevant for the more chemically intert materials as TiO2 and SiO2 whereas e.g. carbon-based materials like fullerenes where surfacemodifications are introduced are more likely to acquire nano-specific properties.
    This is an area that needs further clarification before firm conclusions can be made. Relevant for this discussion is also the fact that many nanoscale particles (e.g. silver, nanoclay, TiO2 and SiO2) are naturally occurring particles that have been used for decades. However, these materials may also be modified with different surface coating, which can alter there physical-chemical properties and toxicity.
    In order to answer the many questions regarding nanomaterials and risk more information and research is required in the future. Some of the gaps can be summarized as follows:
  • Characteristics sufficient for toxicity testing
  • Fate, behavior and kinetics of different nanoparticles
  • Agreement regarding risk assessment methodologies to comply with regulatory regimes
  • More information on chronic effects of nanomaterials
  • Effect of surface functionalisation on toxicity of the nanomaterials
  • Source: Danish Environmental Protection Agency
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