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NIOSH Program Portfolio

 

Manufacturing

NORA Manufacturing Sector Strategic Goals

927ZJLTa - Nanoparticle Metrics for Field and Toxicity Studies (NTRC)

Start Date: 10/1/2009
End Date: 9/30/2014

Principal Investigator (PI)
Name: Mark Hoover
Organization: NIOSH
Sub-Unit: DRDS
Funded By: NIOSH

Primary Goal Addressed
9.0

Secondary Goal Addressed
5.0


Attributed to Manufacturing
100%

Project Description

Short Summary

The project on Nanoparticle Metrics for Field and Toxicity Studies will conduct a comprehensive review and gaps analysis of measurement methods and results to date in the NIOSH Nanotechnology Research Center (NTRC) ongoing laboratory studies of nanotoxicology and field evaluations of nanoparticles in the workplace. Results of that assessment will be used to expand existing measurement methods in the NTRC nanotoxicology studies to provide a more robust evaluation of diameter and other biologically relevant metrics as a function of nanoparticle type, primary diameter, and degree of agglomeration. A characterization methodology for field and toxicity studies that uses an optimal subset of available methods will be included in chapters on measurement methods for NIOSH guidance documents and recommended as a practical approach to support NIOSH Recommended Exposure Limits for specific nanomaterials.



Description

Identification of a unifying metric or metrics across toxicology studies, aerosol measurements, and field measurements would substantially advance the NIOSH NTRC strategic goals of determining whether nanoparticles and nanomaterials pose risks for injuries and illnesses for workers and developing tools to apply and evaluate the effectiveness of risk management methods. As results of NTRC nanotoxicology studies become available to support RELs for specific nanomaterials, identification of practical methods to measure those materials in the field will be critical to successful implementation of the RELs. A barrier to success is lack of scientific certainty about best metrics and measurement methods for nanoparticle diameter and other biologically relevant characteristics that should be assessed across the spectrum of field and toxicity studies. Expanded studies in the field and comprehensive inhalation toxicology studies in the laboratory can use complicated, expensive, and time-consuming methods such as scanning mobility particle sizers (SMPSs) to measure electrical mobility diameter (considered by some to be a “gold” standard measurement), diffusion batteries to measure thermodynamic diameter (possibly a more relevant metric of nanoparticle deposition in the respiratory tract), and multiple-orifice uniform deposition cascade impactors (MOUDIs) or aerodynamic particle sizers (APSs) to measure aerodynamic-equivalent diameter (which is of questionable interpretation for nanoparticles, but highly relevant for micrometer-sized aggregates, agglomerates, or nanomaterial particles). Simpler and less expensive methods are needed for routine field use. The project will link with other NTRC and partner studies and focus on practical methods that are currently being used or might readily be used in NTRC nanotoxicology studies and exposure assessments to detect or respond to nanoparticle metrics needed to support RELs. Our hypothesis is that comparison and evaluation of alternative methods in the on-going NTRC field and toxicity studies will enable identification of a necessary and sufficient set of methods for hazard assessment and risk management.

Specific aims of the project on Nanoparticle Metrics for Field and Toxicity Studies are to (1) conduct a comprehensive review and analysis of measurement methods, results, and gaps to date in the NIOSH Nanotechnology Research Center (NTRC) ongoing laboratory studies of nanotoxicology and field evaluations of nanoparticles in the workplace and (2) use results of that assessment to expand existing measurement methods in the NTRC nanotoxicology studies to provide a more robust evaluation of diameter and other biologically relevant metrics as a function of nanoparticle type, primary diameter, and degree of agglomeration. This work will contribute to a characterization methodology for field and toxicity studies that uses an optimal subset of available methods as a practical approach to support NIOSH Recommended Exposure Limits for specific nanomaterials. Those methods may also be useful to support possible triggering of medical surveillance.

Outputs and progress toward intermediate/end outcomes of this project will be telephone, netmeeting, and direct feedback to NIOSH and partner field and toxicology collaborators, peer-reviewed journal manuscripts, conference presentations, and internet content for the NIOSH Approaches to Safe Nanotechnology and the Nanoparticle Information Library. Intermediate outcomes will be incorporation of integrated nanoparticle measurement guidance and methods by the NTRC field team and toxicity researchers, industry, OSHA, and other external partners.



Objectives

The overall objective of the project on Nanoparticle Metrics for Field and Toxicity Studies is to identify a unifying metric or metrics across toxicology studies, aerosol measurements, and field measurements that would be highly correlated with exposure and risk for a variety of nanomaterials and exposure situations and would substantially advance the NIOSH NTRC strategic goals of determining whether nanoparticles and nanomaterials pose risks for injuries and illnesses for workers and developing tools to apply and evaluate the effectiveness of risk management methods. As results of NTRC nanotoxicology studies become available to support RELs for specific nanomaterials, identification of practical methods to measure those materials in the field will be critical to successful implementation of the RELs. A barrier to success is lack of scientific certainty about best metrics and measurement methods for nanoparticle diameter and other biologically relevant characteristics that should be assessed across the spectrum of field and toxicity studies. Expanded studies in the field and comprehensive inhalation toxicology studies in the laboratory can use complicated, expensive, and time-consuming methods such as the SMPS to measure electrical mobility diameter (considered by some to be a “gold” standard measurement), diffusion batteries to measure thermodynamic diameter (possibly a more relevant metric of nanoparticle deposition in the respiratory tract), and the MOUDI or APS to measure aerodynamic-equivalent diameter (which is of questionable interpretation for nanoparticles, but highly relevant for micrometer-sized aggregates, agglomerates, or nanomaterial particles). Simpler and less expensive methods are needed for routine field use. The project will link with other NTRC and partner studies and focus on practical methods that are currently being used or might readily be used in NTRC nanotoxicology studies and exposure assessments to detect or respond to nanoparticle metrics needed to support RELs. Our hypothesis is that comparison and evaluation of alternative methods in the on-going NTRC field and toxicity studies will enable identification of a necessary and sufficient set of methods for hazard assessment and risk management. The approach of this project will focus on nanoparticles being assessed in the NTRC nanotoxicology studies, including different formulations of carbon nanotubes, fine and ultrafine TiO2, and other metal and metal oxide aerosols. Significantly, the project on Nanoparticle Metrics for Field and Toxicity Studies will (1) conduct a comprehensive review and analysis of measurement methods, results, and gaps to date in the NIOSH Nanotechnology Research Center (NTRC) ongoing laboratory studies of nanotoxicology and field evaluations of nanoparticles in the workplace and (2) use results of that assessment to expand existing measurement methods in the NTRC nanotoxicology studies to provide a more robust evaluation of diameter and other biologically relevant metrics as a function of nanoparticle type, primary diameter, and degree of agglomeration. This work will contribute to a characterization methodology for field and toxicity studies that uses an optimal subset of available methods as a practical approach to support NIOSH Recommended Exposure Limits for specific nanomaterials. Those methods may also be useful to support possible triggering of medical surveillance. Evaluations of this project will include peer review of results for open literature publication and feedback from partnering experts and organization; tracking of the numbers of presentations, papers, and citations of the research results; and references to this research in business publications, nationally and internationally authoritative documents and guidelines, and Material Safety Data Sheets. Ultimately the impact will be assessed by determining the extent to which measurement methods recommended in this project are successful in keeping respiratory, cardiovascular and other occupational disease incidence rates near background in the existing ...



Mission Relevance

Adequate protection of nanotechnology workers and the public requires identification of appropriate measurement metrics for characterizing workplace exposures that are relevant to the metrics used for describing dose-response results from toxicological studies. This project has identified a number of problems related to the performance of methods and instruments used to detect or respond to the metrics that are used in the NIOSH nanotoxicology studies, and that are being used for exposure assessments.

These problems with current measurement approaches and evaluations of nanoparticle metrics need to be addressed to enable reliable measurements and to determine whether there might be a 'unifying' metric that crosses the arenas of the toxicology study aerosol measurements and field measurements and that is highly correlated with exposure and risk for a variety of nanomaterials and exposure situations. There is also a need to gain a better understanding of instrument performance including its feasibility for routine field investigations. Ultimately, such efforts should lead to recommendations that can be used by risk assessors in identifying relevant exposure metrics for estimating risks and developing NIOSH Recommended Exposure Limits (RELs).

The need for the project and the design of the project were based on input from industry partners, participants in the National Nanotechnology Initiative, international collaborators, consensus standards committee participants, and in-house NIOSH experience with nanoparticle metric measurement systems and approaches.

This project is addressing the nanoparticle metrics problems and needs by: (1) conducting a comprehensive review and analysis of measurement methods, results, and gaps to date in the NIOSH Nanotechnology Research Center (NTRC) ongoing laboratory studies of nanotoxicology and field evaluations of nanoparticles in the workplace and (2) using results of that assessment to expand existing measurement methods in the NTRC nanotoxicology studies to provide a more robust evaluation of diameter and other biologically relevant metrics as a function of nanoparticle type, primary diameter, and degree of agglomeration.



Page last updated: June 3, 2011
Page last reviewed: May 23, 2011
Content Source: National Institute for Occupational Safety and Health (NIOSH) Office of the Director

 

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