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NIOSH Program Portfolio

 

Manufacturing

NORA Manufacturing Sector Strategic Goals

927ZGNY - Workplace Monitoring for Carbon Nanofibers/Nanotubes

Start Date: 10/1/2008
End Date: 9/30/2009

Principal Investigator (PI)
Name: Mary Birch
Phone: 513-841-4298
E-mail: mib2@cdc.gov
Organization: NIOSH
Sub-Unit: DART
Funded By: NIOSH

Primary Goal Addressed
9.0

Secondary Goal Addressed
None


Attributed to Manufacturing
50%

Project Description

Short Summary

This project will contribute new monitoring methods for carbon nanofibers/nanotubes (CNF/CNT) and provide an overall exposure picture for workers involved in the production and handling of these materials. Nanotechnology's promise is introducing many new nanomaterials, yet little is known about their health and environmental impacts. CNFs/CNTs may be especially toxic when inhaled—worker exposure is a global concern. Real-time and laboratory methods will be used to monitor CNFs/CNTs and byproducts generated during their manufacture, and a variety of commercial products will be characterized. The project will generate new exposure data and information on the physical and chemical properties of these materials, important Institute goals for Nanotechnology. The methods developed can be applied to existing/emerging nanomaterials, exposure monitoring, and evaluation of exposure controls.



Description

Though little is currently known about the health and environmental risks of emerging nanomaterials, past experience with familiar nanoscale particles and fibers (e.g., diesel exhaust, asbestos) lends insight into their potential risks. Carbon nanofibers and nanotubes are important classes of engineered nanomaterials that may be especially toxic when inhaled due to their composition, size, and fibrous structure. Results of in vitro and in vivo studies raise concerns about the health effects of carbon nanofibers/nanotubes. This is alarming because carbon nanotubes/nanofibers are currently one of the most mass-produced nanomaterials, and the manufacturing processes are rapidly changing. High-volume production presents an exposure risk for workers in this industry.



This project will provide new workplace monitoring data for carbon nanofibers/nanotubes. It will identify processes that contribute to exposure so that preventive measures can be taken. Previous field investigations have found elevated air concentrations of carbon nanofiber materials. Toxic byproducts of the manufacturing process also were identified. Thus, real-world exposure is to a potentially toxic mixture that can be inhaled into the deep lung. Given the variety of metal catalysts and changing manufacturing processes, these materials can have very different physical, chemical, and biological properties. Toxic byproducts also must be considered when assessing risk. Studies to fully characterize workplace exposures are urgently needed



Real-time and laboratory methods will be employed for workplace monitoring of carbon nanofibers/nanotubes and production byproducts. A fully mobile sampling platform equipped with state-of-the-art aerosol instrumentation will be used for detailed, real-time aerosol characterization. Size-selective aerosol sampling will be conducted to investigate the physical and chemical attributes of different particle size fractions. Filter samples will be analyzed for organic compounds, metals, and organic and elemental carbon. Organics will be determined by gas chromatography with mass spectrometry. A novel thermal-optical technique will be used for carbon measurement. Transmission electron microscopy with energy dispersive spectroscopy and electron energy loss spectroscopy will be used to characterize physical attributes and metal content. Metals will be further determined by inductively coupled plasma with atomic emission spectroscopy. Other techniques will be applied as necessary. Field samples will be characterized by multiple metrics to provide a more complete exposure picture for complex mixtures.



Specific project aims are to: 1) characterize different types of commercial products, 2) identify and characterize workplace emission sources, 2) obtain personal exposure data, and 3) control exposures. The overall objective is to reduce the potential future health burden on exposed workers.



Preliminary studies, including laboratory work and field work at two facilities that produce/process carbon nanofiber materials, have been completed. Findings of field surveys were provided to the companies so that appropriate controls and workplace practices can be implemented to reduce exposures. Additional field studies and laboratory research will be completed during FY09-FY10.



A NIOSH HHE report and a journal publication on an in-depth survey conducted at a carbon nanofiber composite facility were completed. Findings of a second survey at a carbon nanofiber manufacturing facility were recently presented (2007 AAAR Conference). Three presentations (total) have been given at major conferences.



Objectives

Carbon nanofibers and nanotubes (CNFs/CNTs) are important classes of nanomaterials that have many commercial applications. The production of CNFs/CNTs and composites thereof is rapidly increasing and the manufacturing processes are continuously changing. In coming years, an estimated two million workers will be required globally to support nanotechnologies, with CNFs/CNTs being some of the most mass-produced nanomaterials. High-volume production increases the exposure risks for workers handling these materials. Though little is currently known about the health and environmental risks of emerging nanomaterials, past experience with familiar nanoscale particles and fibers (e.g., diesel exhaust, asbestos) lends insight into their potential risks. In vitro and in vivo studies raise serious concerns for CNFs/CNTs—the possibility of asbestos-like effects is of particular concern. Field studies are needed to identify, quantify, and control exposures.



The overall objective of this project is to conduct field research to characterize workplace emissions and exposures in facilities that produce/use CNFs/CNTs. In previous field investigations by the PIs, workplace exposures were found to be to a complex mixture of CNFs and multiple manufacturing byproducts. Given the rapidly changing manufacturing processes, CNF/CNT products and associated byproduct emissions can have substantially different physical, chemical, and biological properties. Toxic byproducts also must be considered when assessing risk. Studies to fully characterize workplace exposures are lacking. This project will provide such exposure data and identify processes that contribute to exposure.



Mission Relevance

Nanotechnology is predicted to have a one trillion dollar impact on the global economy by year 2015 and employ about two million workers (Rocco 2003). Many types of nanomaterials are emerging. Nanoscale dimensions can impart highly unusual and useful properties to nanomaterials—properties that may have risks not yet realized. Though the potential risks are still largely unknown, studies raise occupational and environmental concerns. Carbon nanofibers/nanotubes are an important class of nanomaterials that may be especially toxic when inhaled because of their composition and fibrous structure. Manufacture and use of carbon nanofibers/nanotubes are rapidly increasing in a drive to produce new, high-performance products.



This project will contribute new methods and monitoring data for facilities that produce/handle carbon nanofibers/nanotubes. Results can be used by multiple stakeholders—researchers, industry, labor, regulatory agencies—to effect changes and policies that prevent or reduce potentially hazardous exposures. The research community will apply the results to fill knowledge gaps on nanomaterial properties and risks. Results can be used by industrial hygienists and employers for hazard identification and monitoring, and by regulatory agencies for environmental/occupational monitoring and standards setting. Ongoing work with a carbon a carbon nanofiber manufacturer has already had positive impact on reducing worker exposure.



The project is aligned with strategic goals (SGs) for the Manufacturing sector and the Respiratory Diseases, Exposure Assessment, Global, and Nanotechnology cross sectors. It specifically addresses the following intermediate and activity/output goals:



Respiratory Diseases (SGs 1, 2, 5)



Intermediate Goal 2.3 (09PPRDRIG2.3): prevent and reduce "fiber"-induced respiratory diseases.

Intermediate Goal 5.2 (09PPRDRIG5.2): characterize respiratory exposures and measures used to reduce exposures…in work settings where engineered nanomaterials are produced or used. Activity/Output Goal 2.1 (09PPRDRAOG5.2.1): develop partnerships and conduct field evaluations of facilities where nanomaterials are produced or used.

Intermediate Goal 5.3 (09PPRDRIG5.3): develop guidance for facilities that produce or use nanomaterials.



Exposure Assessment (SG2)



Intermediate Goal 2.10 (09PPEXAIG2.10): Develop reference materials and values for use in exposure assessment studies. Activity/Output 2.10.1 (09PPEXAAOG2.10.1): Development of reference materials or values either through partnerships, literature reviews or direct synthesis of the reference materials.

Intermediate Goal 2.11 (09PPEXAIG2.11): Address critical exposure assessment needs in emerging areas such as nanotechnology…Activity/Output 2.11.1 (09PPEXAAOG2.11.1): Development of exposure assessment tools to characterize and evaluate the exposure to these emerging areas. Activity/Output 2.11.2 (09PPEXAAOG2.11.2): Application of exposure assessment tools to these emerging areas.



Nanotechnology (SGs 1, 4)



Intermediate Goal 1.1 (09PPNAN1G1.1): Determine the key factors influencing the generation, dispersion, deposition, and re-entrainment of nanomaterials in the workplace, including the role of mixed exposures.

Intermediate Goal 1.2 (09PPNANIG1.2): Quantitatively assess exposures to nanomaterials in the workplace including inhalation and dermal exposure. Determine how exposures differ by work task or process.

Intermediate Goal 5.2 (09PPNANIG5.2): Develop new measurement methods.



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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