Assessment of Progress - Research Progress on Environmental Health and Safety Aspects of Engineered Nanomaterials - page 37

organisms, transformation of ENMs, and such changes in abiotic factors as nutrients because of
nanomaterials are all important variables that need more research attention.
 Identification of benchmark (positive and negative) and reference materials 11 for use in studies
and measurement tools and methods to estimate exposure and dose in complex systems.
The committee's first report identified a pressing need to establish reference materials for all
aspects of nanomaterial-related research. Availability of toxicity benchmark materials (positive and
negative) and reference materials for metrology are of high value for hazard ranking and risk assessment.
NIST has issued two well-characterized, certified reference nanomaterials, TiO 2 (P-25 12 ) and gold (10, 30,
and 60 nm), that could be used in toxicologic studies.
The International Organization for Standardization defines a reference material as a “material,
sufficiently homogeneous and stable with respect to one or more specified properties, which has been
established to be fit for its intended use in a measurement process” (ISO 2006). Therefore, existing
reference materials are standards solely for material characterization (for example, NIST gold
nanoparticles, standard reference material RM 8011, 8012, and 8013) or for standardizing measurement
instrumentation. Benchmark materials for use in toxicologic and ecotoxicologic research need to be
carefully characterized with respect to both physicochemical and toxicologic properties. The latter
probably depend on several physicochemical properties (for example ENM size, charge, or in vivo
solubility) that may make it necessary to establish more than one reference material for hazard ranking.
Generally accepted positive or negative benchmark materials for toxicologic purposes have not yet been
identified, but suggestions have been made in some individual studies (Aitken et al. 2008; Stone et al.
2010). Well-characterized benchmark ENMs should serve as references against which new and untested
ENMs can be ranked as an initial step in hazard identification. Such information, with exposure data, can
serve as a basis of risk assessment. The committee therefore believes that overall progress in this
objective is inadequate and therefore has designated it red.
INDICATORS OF PROGRESS IN IMPLEMENTATION
Enhancing Interagency Coordination
In its first report, the committee acknowledged the value of the coordinating role played by the
NNI and pointed to some changes that have enhanced interagency coordination, including the naming of
an NNCO EHS coordinator by the Office of Science and Technology Policy (OSTP). However, the
committee concluded in its first report (p. 169) and continues to believe that accountability for
implementation of the NNI EHS research strategy is limited and hampered by the absence of an entity
that has sufficient management and budgetary authority to direct implementation throughout NNI
agencies and to ensure its integration with EHS research being undertaken in the private sector, the
academic community, and international organizations. Ensuring implementation of the strategy and
gauging progress in high-priority research also requires an assessment of the effectiveness of available
mechanisms for interagency collaboration and frequent periodic identification—not just of recent, current,
or newly initiated interagency research collaborations but also of funding needs. The committee's
assessment of progress against its two indicators for interagency collaboration is as follows.
11 The committee differentiates between benchmark materials and reference materials. Reference Material,
defined by ISO (2006), is a “material, sufficiently homogenous and stable with respect to one or more specified
properties, which has been established to be fit for its intended use in a measurement process”. The focus is on
its physicochemical properties and its use in metrology when certified by national or international agencies (for
example, NIST gold nanoparticles and TiO 2 nanoparticles). Benchmark materials are well-characterized
physicochemically and toxicologically, and can serve as positive or negative controls for comparing
exposure-dose-response relationships of nanomaterials in toxicologic tests and in risk assessment.
12 P-25 is the product number for titanium dioxide.