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Toward advancing nano-object count metrology: a best practice framework.

Brown SC, Boyko V, Meyers G, Voetz M, Wohlleben W - Environ. Health Perspect. (2013)

Bottom Line: Although particle size remains the sole discriminating factor for classifying a material as "nano," inconsistencies in size metrology will continue to confound policy and decision making.To enable future risk-based refinements of these emerging definitions, we recommend that this framework also be considered in environmental and human health research involving the implications of nanomaterials.Strong cooperation between industry, academia, and research institutions will be required to fully develop and implement detailed frameworks for nanomaterial identification with respect to emerging count-based metrics.

View Article: PubMed Central - PubMed

Affiliation: Corporate Center for Analytical Sciences, DuPont Central Research and Development, Wilmington, Delaware, USA.

ABSTRACT

Background: A movement among international agencies and policy makers to classify industrial materials by their number content of sub-100-nm particles could have broad implications for the development of sustainable nanotechnologies.

Objectives: Here we highlight current particle size metrology challenges faced by the chemical industry due to these emerging number percent content thresholds, provide a suggested best-practice framework for nano-object identification, and identify research needs as a path forward.

Discussion: Harmonized methods for identifying nanomaterials by size and count for many real-world samples do not currently exist. Although particle size remains the sole discriminating factor for classifying a material as "nano," inconsistencies in size metrology will continue to confound policy and decision making. Moreover, there are concerns that the casting of a wide net with still-unproven metrology methods may stifle the development and judicious implementation of sustainable nanotechnologies. Based on the current state of the art, we propose a tiered approach for evaluating materials. To enable future risk-based refinements of these emerging definitions, we recommend that this framework also be considered in environmental and human health research involving the implications of nanomaterials.

Conclusion: Substantial scientific scrutiny is needed in the area of nanomaterial metrology to establish best practices and to develop suitable methods before implementing definitions based solely on number percent nano-object content for regulatory purposes. Strong cooperation between industry, academia, and research institutions will be required to fully develop and implement detailed frameworks for nanomaterial identification with respect to emerging count-based metrics.

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Number (A) and mass particle size (B) distributions determined for samples of deionized water, distilled water, tap water, and 5 μg/mL NaCl. Dp, particle diameter; NaCl, sodium chloride. Adapted from Knight and Petrucci (2003) and reprinted with permission from ACS Publications [Analytical Chemistry. Study of residual particle concentrations generated by the ultrasonic nebulization of deionized water stored in different container types, 75:4486–4492 (2003). Knight M, Petrucci GA. Copyright 2003 American Chemical Society].
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f3: Number (A) and mass particle size (B) distributions determined for samples of deionized water, distilled water, tap water, and 5 μg/mL NaCl. Dp, particle diameter; NaCl, sodium chloride. Adapted from Knight and Petrucci (2003) and reprinted with permission from ACS Publications [Analytical Chemistry. Study of residual particle concentrations generated by the ultrasonic nebulization of deionized water stored in different container types, 75:4486–4492 (2003). Knight M, Petrucci GA. Copyright 2003 American Chemical Society].

Mentions: Common water sources are also likely to be contaminated with low mass, but high number count, nano-objects (Figure 3). The same can be said for common vessels such as glass beakers and a variety of plastic containers used in laboratory analysis (Knight and Petrucci 2003). Under the current recommendation, many everyday materials would be classified as nano, which could inappropriately focus resources on a broad range of materials that were presumably not intentionally targeted by the EC definition. Clearly, there remains a need for refining the definition, including further appropriate specifiers to better address these issues. The inclusion of a specified volume percent over a limited size range (e.g., 1 nm–10 μm) and/or a total volume cutoff filter (e.g., a qualifying threshold or dust threshold) would largely enhance the identification of potential materials of interest and may also serve to simplify the associated metrology by enabling the application of more traditional metrology methods.


Toward advancing nano-object count metrology: a best practice framework.

Brown SC, Boyko V, Meyers G, Voetz M, Wohlleben W - Environ. Health Perspect. (2013)

Number (A) and mass particle size (B) distributions determined for samples of deionized water, distilled water, tap water, and 5 μg/mL NaCl. Dp, particle diameter; NaCl, sodium chloride. Adapted from Knight and Petrucci (2003) and reprinted with permission from ACS Publications [Analytical Chemistry. Study of residual particle concentrations generated by the ultrasonic nebulization of deionized water stored in different container types, 75:4486–4492 (2003). Knight M, Petrucci GA. Copyright 2003 American Chemical Society].
© Copyright Policy - public-domain
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3852792&req=5

f3: Number (A) and mass particle size (B) distributions determined for samples of deionized water, distilled water, tap water, and 5 μg/mL NaCl. Dp, particle diameter; NaCl, sodium chloride. Adapted from Knight and Petrucci (2003) and reprinted with permission from ACS Publications [Analytical Chemistry. Study of residual particle concentrations generated by the ultrasonic nebulization of deionized water stored in different container types, 75:4486–4492 (2003). Knight M, Petrucci GA. Copyright 2003 American Chemical Society].
Mentions: Common water sources are also likely to be contaminated with low mass, but high number count, nano-objects (Figure 3). The same can be said for common vessels such as glass beakers and a variety of plastic containers used in laboratory analysis (Knight and Petrucci 2003). Under the current recommendation, many everyday materials would be classified as nano, which could inappropriately focus resources on a broad range of materials that were presumably not intentionally targeted by the EC definition. Clearly, there remains a need for refining the definition, including further appropriate specifiers to better address these issues. The inclusion of a specified volume percent over a limited size range (e.g., 1 nm–10 μm) and/or a total volume cutoff filter (e.g., a qualifying threshold or dust threshold) would largely enhance the identification of potential materials of interest and may also serve to simplify the associated metrology by enabling the application of more traditional metrology methods.

Bottom Line: Although particle size remains the sole discriminating factor for classifying a material as "nano," inconsistencies in size metrology will continue to confound policy and decision making.To enable future risk-based refinements of these emerging definitions, we recommend that this framework also be considered in environmental and human health research involving the implications of nanomaterials.Strong cooperation between industry, academia, and research institutions will be required to fully develop and implement detailed frameworks for nanomaterial identification with respect to emerging count-based metrics.

View Article: PubMed Central - PubMed

Affiliation: Corporate Center for Analytical Sciences, DuPont Central Research and Development, Wilmington, Delaware, USA.

ABSTRACT

Background: A movement among international agencies and policy makers to classify industrial materials by their number content of sub-100-nm particles could have broad implications for the development of sustainable nanotechnologies.

Objectives: Here we highlight current particle size metrology challenges faced by the chemical industry due to these emerging number percent content thresholds, provide a suggested best-practice framework for nano-object identification, and identify research needs as a path forward.

Discussion: Harmonized methods for identifying nanomaterials by size and count for many real-world samples do not currently exist. Although particle size remains the sole discriminating factor for classifying a material as "nano," inconsistencies in size metrology will continue to confound policy and decision making. Moreover, there are concerns that the casting of a wide net with still-unproven metrology methods may stifle the development and judicious implementation of sustainable nanotechnologies. Based on the current state of the art, we propose a tiered approach for evaluating materials. To enable future risk-based refinements of these emerging definitions, we recommend that this framework also be considered in environmental and human health research involving the implications of nanomaterials.

Conclusion: Substantial scientific scrutiny is needed in the area of nanomaterial metrology to establish best practices and to develop suitable methods before implementing definitions based solely on number percent nano-object content for regulatory purposes. Strong cooperation between industry, academia, and research institutions will be required to fully develop and implement detailed frameworks for nanomaterial identification with respect to emerging count-based metrics.

Show MeSH