and possibly nanoparticle reactivity. A more mechanistic approach might provide the foundation of the development of predictive models, provide insights into exposure pathways, and identify organisms at risk. Results of this research may provide insights into exposure pathways and organisms at particular risk, so substantial effort is warranted.
Research need 4 is “Understand the transformation of nanomaterials under different environmental conditions.” Physical, chemical, and biologic transformations are all identified as meriting research.
There were 10 projects that were not sorted into the five research needs. Their importance was noted in that they could also lead to nanotechnology applications that contribute to lessening current environmental contamination.
In summary, all the research needs identified as having priority in the NNI document are appropriate and even critical for providing information needed for informed risk assessment. The committee reinforces the need for characterization methods to identify nanomaterials in biologic and environmental matrices and the products of nanomaterial-environment interactions. As stated by the NNI, this must be an overarching consideration. The call to focus on “as-manufactured” nanomaterials may misdirect interim risk assessments by creating large gaps in the understanding of how “manufactured” nanomaterials and those found in natural systems may differ.
With the caveats described above, the priorities in this category are appropriate in that a consideration of hazard below the level of ecosystems often precedes ecosystem-level evaluation. However, estimates of transport and transformation are required to assess environmental exposure and should therefore have higher priority than evaluation of ecosystemwide effects because the latter cannot be usefully studied without knowing what the likely environmental concentrations will be and what organisms might be exposed. Therefore, the committee recommends that the research needs be rearranged as (2), (4), (1), (3), (5). Exposure and transport processes would be characterized before effects. That would provide a rationale for the selection of bioassay species. Transformation processes would be characterized before higher-level ecosystem effects. At present, the distribution of projects among the research needs does not appear to be consistent with the proposed priorities or with our recommended sequence. Attention should be given to making resource allocation consistent with the prioritized research needs.
Although the research strategy appears to reflect an important collection of existing federally funded research, there are several gaps in the identified research needs:
The strategy document does not specifically identify the need for studying naturally occurring or incidental nanoparticles that have similar structures or that may be identical with manufactured nanomaterials.
The document does not identify development of protocols to evaluate nanomaterial loss from products as a research need despite an apparent trend