Timing, hosts and locations of (grouped) events of NanoImpactNet

NanoSafetyCluster - Compendium 2012
intended to track ENP fate during wastewater treatment
process or following the deposition of diffuse ENP directly to
soil ecosystems in WP 2.
Obj.4: Study ENP fate and behaviour through wastewater
treatment processes and in soils.
Baseline. Published studies on the environmental fate of oxide
NPs have focused mainly on transport through porous media
(groundwater/soils) and will be useful to an extent in NanoFATE.
Despite the fact that wastewater discharges provide a major
route for emissions of oxide NPs in cosmetic/personal care
products to the environment, there has been very little
attention focused on their fate during wastewater treatment
(Chang et al., 2007). Clearly such studies are vital to frame
environmental hazard and risk.
NanoFATE progression beyond the “state-of-the-art”.
NanoFATE will improve current understanding in relation to ENP
behaviour during wastewater treatment by providing the
following information relating to ENPs post release fate that will
support predictions of ENP concentrations delivered to waters
via discharges and to soil via sludge disposal.
1. Examination of the colloidal behaviour of ENPs in real
wastewater matrices using small angle neutron scattering
to directly quantify, in real time, ENP partitioning during
primary (settlement) treatment, between (i) non-settleable
constituents which continue through the effluent stream to
secondary treatment, and (ii) sewage sludge which settles
out within typical residence times of approximately 2 – 6
hours in primary settlement tanks (NERC, UGOT).
2. Distribution of tagged ENPs in flow-through test reactors
installed at a UK sewage works and using real activated
sludge feed. Analysis of the aqueous and solid phases for
the tagged ENP would be done by ICP-MS and fluorescence
or SQUID magnetometry (IHPP, NERC).
3. Use of scanning and transmission electron microscopy and
dynamic light scattering techniques to measure changes in
aggregate size, shape and fractal dimension of ENPs to
characterise the nature and mechanisms of ENP
flocculation during wastewater treatment (UOXF.DJ). Also
IHPP has excellent field emission scanning microscope
Leo1530 that could be employed here.
4. Use of scanning and transmission electron microscopy and
nanoparticle visualisation techniques (e.g. NanoSight) to
measure changes in ENP size and aggregation in different
soil pore water and wastewater extracts to provide
estimates of ENP dissolution rates (UOXF.DJ, UGOT).
The data derived from the studies conducted above will be used
to refine the estimates of exposure conducted in the risk
assessment phase of the project. Additionally, the data on
dissolution rates will be used to support later detailed
measurements of ENP bioavailability as particles or as free,
colloidal bound forms during ecotoxicity testing in studies
conducted in different environmental media in WP 4.
Obj.5: Determine the chronic toxicity of ENPs of different
properties, including co-exposures with other stressors (e.g. UV
and combustion derived pollutants).
Baseline. To date, published data concerning the effects of ENP
in vivo are principally restricted to acute toxicity tests (Handy et
al 2008; Luoma 2008). Chronic toxicity data are mostly lacking.
Furthermore, since the available studies each used a different
ENP with different characteristic, it is difficult to compare these
data directly. Another issue that is often highlighted (Royal
Commission on Environmental Pollution, 2008; Luoma 2008),
but to date remains poorly investigated is that of co-exposure of
ENP with other pollutants and/or environmental stressors. Both
have the potential to lead to greater than additive effects
through processes, such as facilitating pollutant transport by
ENPs (AKA piggybacking) and ROS generation (Baun et al.
2008).
NanoFATE progression beyond the “state-of-the-art”. The
knowledge gaps concerning ENP effects highlighted above
indicate the pressing need to provide more detailed information
on aspects of ENP toxicity. These include issues such as the
relative sensitivities of species, acute-to-chronic ratios, the
effects of ENP properties on toxicity, and the interactive effects
of ENP with other co-stressors. NanoFATE will deliver such
information by the following studies.
1. Literature review of data on ENP ecotoxicity for aquatic
and terrestrial species. This will include information of the
characteristics of the particles used for testing, the
physicochemical properties of the test medium and the
nature of the dose response relationship for different
endpoints. The data set will be enhanced by our own
studies of chronic toxicity on our selected set of ENPs in
species from both aquatic (microorganisms as biofilm
communities, algae, Daphnia, mussel) and terrestrial
(nematode, springtail, earthworm, woodlouse) organisms
(NERC, VUA, UAVR).
2. Establishing whether UV co-exposure affects toxicity in
selected species in vivo for ZnO ENPs in Daphnia. This will
build on work that has established that the cytotoxicity of
some UV absorbing ENPs is mediated through radical
oxygen species generation and is enhanced in the presence
of UV light in mammalian cells (Sayes et al., 2006) and
bacteria (Adams et al., 2006) (UAVR).
3. Assessing whether the ability of ENPs to bind and transport
other molecules into biological systems modifies the
toxicity of co-occurring pollutants, as shown previously for
polycyclic aromatic hydrocarbon in the presence of sucrose
polyester ENPs (Moore et al., 1997). While relevant to all
the selected ENPs it is especially of concern for CeO 2 ENPs,
which may serve to co-transport other combustion
pollutants into biota. This will be addressed by taking a
multiple exposure approach and analysing if the
combinations of CeO 2 ENP with associated PAHs lead to
higher uptake and effects than should be observed from
the two components in isolation (UNIPMN, VUA, NERC).
98 Compendium of Projects in the European NanoSafety Cluster