Getting to Green - Research Progress on Environmental Health and Safety Aspects of Engineered Nanomaterials - page 51

Several features of Figure 4-1 merit emphasis. The relationships among its components are
dynamic, and there are multiple feedbacks (represented by the arrows) among them. The success of the
research enterprise hinges on the creation of a knowledge commons and engagement of the broad
community of researchers who are addressing potential risks to human health and ecosystems. It also
requires stakeholder engagement, particularly of the manufacturing sector, to ensure that the materials
studied reflect those in use and that the most critical research questions are addressed. Leadership in its
development and stewardship of its maintenance are also essential.
In the discussion below, the committee analyzes the findings of Chapter 3 in the context of the
flow of activities in the nanotechnology EHS research enterprise (Figure 4-1), examining pathways to
advance research and mechanisms to improve implementation of the enterprise with an eye to “getting to
green” on the committee's indicators (Boxes 3-1 and 3-2). First, research progress is considered, and the
steps needed to advance the research are described. The discussion is divided into six major subjects as
reflected in the research enterprise: nanomaterial processes and mechanisms, material sources and
development of reference materials, model development, methods and instrumentation, the knowledge
commons, and nanomaterial interactions in complex systems. Then, progress on mechanisms to ensure
implementation of the research is evaluated, and the steps needed to advance implementation of the
research are discussed.
FUNDAMENTAL PROCESSES THAT AFFECT NANOMATERIAL EXPOSURE AND HAZARD
The committee's first report identified the need for research on cross-cutting processes that affect
both exposure and hazard (see Figure 1-1). The research entails identifying fundamental processes,
typically through laboratory experiments. A description of the processes is needed to develop general and
predictive capabilities to assess risks that move beyond case-by-case evaluations of ENMs. The process-
based activities described in Figure 4-1 are enabled by continual development of methods and
instrumentation. The experimental approach is updated through understanding of material properties and
the evolving physical, chemical, and biologic processes that affect exposure and hazard. Hypothesized
properties or mechanisms can be scrutinized in well-defined laboratory experiments and in observations
of ENM behavior in complex systems, from in vivo experiments to models of ecosystem interactions in
microcosms, mesocosms, and field observations. Boundaries between well-defined laboratory and
complex systems may be blurred, but the key contrast is that between a reductionist approach to
unraveling elements that may affect organisms, populations, and ecosystems and holistic examination of
ENMs in complex systems. Both approaches are needed, and they are complementary.
Ideally, the agenda for process-based research is influenced in part by findings on the extent to
which research reduces uncertainty in the understanding of potential risks. Reducing uncertainty requires
updating of models to increase our understanding of risks to human health and ecosystems, motivated in
part by needs of stakeholders (whether workers producing ENMs or consumers of ENM-enabled
products). Information generated from process-based research influences how ENMs are produced,
including considerations of life-cycle risks and relevant reference materials for conducting studies.
Substantial progress (green) has been made in exploring mechanisms that control the dynamics
and transformation of ENMs. However, only moderate (yellow) progress has been achieved in
development of methods to quantify effects of ENMs in experimental systems; this level of progress may
reflect the complex nature of in vivo experiments and the need for model development and verification.
The roles of methods and instrumentation in understanding mechanisms of ENM transformations,
distribution, and effects highlight the state of progress in developing methods for ENM characterization
and detection in relevant media; and this indicator has been noted as green. That stands in strong contrast
with the relatively limited progress made in translating methods to readily available instrumentation for
characterizing ENM properties and their transformations; this indicator was denoted as red, and the lack
of progress represents a key impediment to advancing understanding of processes and mechanisms.