Recognize the challenges in comparing data. For example, size and size distributions from transmission electron microscopy are not all the same. They are not the raw data; the image is. Although it is necessary to obtain a representative sample from a set of images, new standard methods for nanomaterials (for example, NIST/NCL 2010; ASTM 2011) reference best practices to control image selection bias (for example, Allen 1996; Jillavenkatesa et al. 2001), and evaluations of bias in instrumentation software for defining particle boundaries are being considered. It is difficult to develop structure-activity relationships when the structures are not concretely defined.

Reduce barriers to nanomaterial innovators contributing to databases by engaging with them, understanding the complexities, and finding solutions that reduce the barriers.

Provide incentives for companies to provide information on nanomaterials that they have pioneered. This will require finding creative ways to protect intellectual property.

Work toward a model, such as the PDB of nanomaterials concept, but engage nanomaterial-synthesis experts at the beginning to identify and find solutions to obstacles.

TABLE 4-1 Summary of Research Needs Identified in Chapter As Mapped to the Tools

Well-characterized materials are needed, including: reference materials of varied size, shape, aspect ratio, surface charge, and surface functionality for testing; “real-world” materials for testing; “weathered” nanomaterials that are representative of those expected in vivo or in situ; materials that can be tracked (for example, for biodistribution or environmental partitioning studies) without introducing experimental artifacts in exposure and toxicity studies; and standard reference materials to use in calibrating assays and measurement tools.
Develop and validate new or modify existing standard toxicity-testing protocols for ENMs, including relevant cell types and organisms, appropriate dosimetry and toxicity end points (for example, chronic effects), and gene and protein expression to identify and validate toxicity mechanisms, such as biodistribution of ENMs and toxicity-pathway models.

Develop methods to extrapolate and predict long-term low-dose effects from short-term high-dose effects, and validate their accuracy through blinded test methods.

Develop screening methods that can indicate the potential for bioavailability and potential for effects due to chronic ENM exposure or for indirect effects, that is, not direct toxicity from ENM exposures (for example, the effects of ENMs on carbon and nitrogen cycling).

Develop and validate standard methods for measuring and reporting attachment affinities of ENMs to biologic and environmental surfaces to facilitate assigning values to parameters in exposure models.

Develop methods to determine the reactivity and stability of ENMs in biologic and environmental samples, including standard measures for assessing and reporting reactivity (for example, generation of reactive oxygen species).

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