Assessment of Progress - Research Progress on Environmental Health and Safety Aspects of Engineered Nanomaterials - page 28

characterizing production amounts of nanomaterials is therefore likely to remain incomplete for some
time and has been given an indicator status of yellow.
 Developing inventories of intended uses of nanomaterials and value-chain transfers
Research in NIST and EPA-NSF funded centers is quantifying releases of nanomaterials from
composite matrices, a likely disposition of many nanomaterials. Those centers are characterizing the
release of CNTs, nanoclays, and nanosilver from porous foams and solid polymers through simulated
abrasion and in various biologic fluids (Wohlleben et al. 2011; Liu et al. 2012; Nguyen et al. 2012). Such
nano-composite materials impart antimicrobial, strength, or flame-retardant properties to fabrics, foams,
and plastics that may be used in consumer products.
Analysis of value-chain transfers of nanomaterials that enter commerce from primary production
to integration into a multitude of consumer products is also being conducted in an EPA-NSF funded
center and in an NSF-funded center. Such analyses remain inadequate, perhaps because few
nanomaterials are widely used in commerce. Given the mixed picture of progress, the committee
designated this item as yellow.
 Identifying critical release points along the value chain
As discussed in the first report, “each nanomaterial or product containing nanomaterials along the
steps of the value chain has an associated life cycle of production, distribution, use, and end-of-life
releases that may affect human health and the environment” (p. 56). There has been progress in
developing inventories of a small number of key nanomaterials and in mapping key elements of the value
associated with a subset of these materials, but actual modeling of releases of nanomaterials to the
environment along the value chains does not appear to have been initiated to any important degree.
Limited by progress in the prerequisite steps of compiling information on inventories in the value chains
highlighted above, identification of likely release points that may result in direct exposure of humans in
the workplace or during transportation, use and end-of-use of nanomaterial-containing products, and the
associated points of release to ecosystems has not been quantitatively modeled.
Since the preparation of the committee's first report, additional commitments by federal agencies
and their collaborators have been identified. Many of those efforts are summarized in the NNI budget
supplement for 2013 (NSET 2012a). In 2013, NIST expanded its nanotechnology EHS program to focus
on the safe manufacture, use, and disposal of ENM-containing products. Those activities include
development of measurement methods and standards to detect ENMs in nanomaterial-enabled products
and to assess their releases. NIST has indicated that this work will focus on the ENMs of greatest
regulatory interest according to production volume (NSET 2012a, p. 17). Candidates have been reported
to include silver TiO 2 , cerium oxide, CNTs, and clay-based composites. Release to all environmental
media is of interest, but the focus appears to be on airborne releases, with NIST and CPSC implementing
multiyear interagency agreements to cooperate in these efforts. EPA also has indicated an expansion of
efforts to characterize properties of ENMs in products that affect their release, fate, and transport in the
environment. EPA appears to be focusing its efforts on carbon-based, metal-based, and metal oxide-based
products. This focus is likely to improve our understanding of the potential for release of ENMs from
products throughout the value chain. In support of those efforts, the EPA-NSF funded centers are focused
on increased understanding of human exposures to ENMs, including those released from products in
commerce. CPSC staff are reportedly also supporting such efforts in the centers. NIOSH and EPA are
conducting testing to evaluate release of nanosilver from uses of nanomaterial-containing consumer
products. Like NIST, CPSC, and EPA, NIOSH continues its focus on airborne releases of nanomaterials
from products. An increasing number of studies are measuring releases of ENMs at manufacturing sites
(Tsai et al. 2008, 2009, 2012; Methner et al. 2010; Kuhlbusch et al. 2011); however, there is a lack of data
on consumer exposure along the value chain. Chen et al. (2010) simulated human exposure to a TiO 2 -
containing aerosol in a spray that can be used as a cleaning agent. Federal agencies—including NIST,