Challenges of Regulation and Risk Assessment of Nanomaterials

6. ECOTOXICITY AND ENVIRONMENTAL FATE
6.1. Summary record
The objectives of the ecotoxicology session were to discuss the links between ecological risk
assessment and regulatory issues and needs, and to present an update of the research in aquatic and
terrestrial toxicity and environmental fate and behaviour of nanomaterials. In addition,
communication with a wide range of stakeholders was an important goal of the session as for the
whole workshop. The first part of the session included two presentations about methodological
issues and concepts, which was followed by a dedicated podium discussion to allow a focused
dialogue on these topics. The second part of the session included four presentations about
environmental fate ecotoxicological research, also followed by a general discussion. This summary
reports the main message from the presentations and the discussion.
Given the wide use of nanomaterials and nanotechnologies, and the increasing importance of this
field in the economy, there is a need to act to regulate nanotechnologies and to assure the safety of
nanoproducts. In the area of environmental protection, there are real challenges related to lack of
information, uncertainties, and complexity of ecological systems. In order to achieve the
management of risk and address any issues in regards to public perception, each stakeholder group
should deal with its own challenges. Regulators have to establish a regulatory strategy, and indicate if
and how nano-specific regulations are needed; Industry on the other side, should keep in mind that
as a general rule, products placed on the market have to be safe and they should collect data to
demonstrate that; finally, the research area should be very clear about actual and future knowledge
requirements, and where uncertainties may not be reduced. The best way forward to achieve the
goals of sustainable nanotechnology is to do a tiered, integrated assessment, i.e. by including socioeconomic
issues besides hazard and exposure assessment, using different tools at different stages of
the product life cycle (e.g. from conceptualization to market placement, and finally to the end of the
product’s life), and expressing risk as magnitude and probability. In particular, it was stated in this
session that the use of NOEC is not appropriate for risk assessment of nanomaterials, and that the
use of non-linear dose-response curves as suggested by Environment Canada would allow the use of
models which would include all relevant available data and thus the estimation of probability of risk.
This would allow assessment of different scenarios and the effectiveness of risk management
measures. In a tiered integrated assessment framework, integrating testing strategies are essential to
identify the best ecotoxicological tests for each assessment tier. Standardized schemes are already
available, however modifications to deal with nanomaterials peculiarities are deemed necessary. In
addition, given the large diversity of nanomaterials, it is impossible to consider a case-by-case
assessment in the long term. A revised scheme should allow grouping of materials with comparable
properties, including additional ecotoxicity endpoints relevant for nanomaterials and for all the
environmental compartments (e.g. soil, water, sediments). Grouping of nanomaterials allows a
reduced testing effort. Only a specific number of materials belonging to a derived specific group, will
be studied in detail to provide comprehensive information on properties and effects of the group.
Some modifications of the existing OECD guidelines have already been proposed concerning e.g.
sample preparation, exposure conditions, and effects measurement techniques. During the
discussion links between available data and regulators needs were addressed. In particular, it was
stated that no effect data are important and therefore should be published, since toxicity of some
nanomaterials could be overstated; it was also highlighted that the actual dataset is skewed toward
sensitive organisms. However, evidence indicates that the range of concentrations tested in
ecotoxicological tests reported in the literature, even if perceived high and unrealistic, are not far
from the actual concentrations found for example in sewage treatment plants and possible in landfill
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