CDC logoSafer Healthier People CDC HomeCDC SearchCDC Health Topics A-Z
NIOSH - National Institute for Occupational Safety and Health

Skip navigation links Search NIOSH  |  NIOSH Home  |  NIOSH Topics  |  Site Index  |  Databases and Information Resources  |  NIOSH Products  |  Contact Us

NIOSH Program Portfolio

 

Manufacturing

NORA Manufacturing Sector Strategic Goals

927ZBBT - Ultrafine TiO2 Surface and Mass Concentration Analysis

Start Date: 10/1/2007
End Date: 9/30/2010

Principal Investigator (PI)
Name: Aleks Stefaniak
Phone: 304-285-6302
E-mail: boq9@cdc.gov
Organization: NIOSH
Sub-Unit: DRDS
Funded By: NIOSH

Primary Goal Addressed
5.0

Secondary Goal Addressed
None


Attributed to Manufacturing
50%

Project Description

Short Summary

Industrial hygienists routinely use 37-mm filter cassette samplers to measure worker exposures to metals, including uTiO2; therefore, no new sampling equipment will be required to use this method. Additionally, because the equipment necessary for sample analysis is inexpensive compared to bench top atomic spectroscopy instruments this method is readily usable by many commercial analytical laboratories and poses few barriers to adoption. This method will be useful for characterizing exposure to uTiO2 in environments where aerosol exposure is heterogeneous (e.g., workplaces). Such a method will provide exposure assessors and epidemiologists with a method for investigating pulmonary effects potentially due to uTiO2 exposure. These data are important to risk assessors for understanding inhalation exposure-response pathways for uTiO2 and ultimately for developing risk models and, if necessary, exposure limits to protect worker health.



Description

We hypothesize that ultrafine uTiO2 surface area can be measured with specificity on heterogeneous particle-laden filter samples using surfactant isotherms and/or fluorescence labeling. Our project aims are to 1) develop a model for quantifying bulk ultrafine uTiO2 powder specific surface area using fluorescence labeling, 2) extend the model to evaluate surface area of aerosolized uTiO2 particles collected on filter media in a laboratory chamber, and 3) test the proposed model in a ultrafine uTiO2 primary production workplace.

In this project, fluorescent dye will be used to collect adsorption isotherms to estimate the specific surface area of ultrafine uTiO2 particles. Our project aims are to:

1) Characterize a commercially-available bulk uTiO2 powder for use as a test material (density, morphology, total surface area, purity, and crystallinity),

2) Develop a technique for determining background surface area of filter media using nitrogen gas isotherms,

3) Determine the surface area of uTiO2-laden filter media using nitrogen gas isotherms, and

4) Determine the surface area of aerosolized uTiO2 particles collected on filter media in a laboratory chamber.

5) Additionally, we will evaluate the feasibility of determining uTiO2 surface area with specificity in heterogeneous aerosol samples using a fluorescing compound such as perylene diimide dye adsorbed to particle surfaces, and

6) Collect samples in a work place with uTiO2 exposures and analyze for surface area using the newly developed method and mass using mass spectroscopy on a single filter sample.

Successful completion of this research project will result in a method for determining two metrics of uTiO2 exposure, surface area by gas adsorption and mass by spectroscopy, from a single filter sample and assessment of the method precision. Because measurement of surface area by gas adsorption is not elemental specific, this method will be useful for characterizing exposure to uTiO2 in environments where aerosol exposure is homogeneous (e.g., exposure "as delivered" to laboratory animals during inhalation experiments). A highly successful research project will result in a method for determining two metrics of uTiO2 exposure, surface area with specificity by using a fluorescing dye (e.g., perylene diimide) and mass by spectroscopy, from a single filter sample.

Once established with P25 TiO2 particles, our goal is to evaluate the method for solution-based fluorescence estimation of TiO2 surface area using: 1) two different crystalline forms (pure anatase, pure rhutile, mixtures of these forms), 2) material produced by two different methods (wet chemistry method, flame synthesis method), and 3) different sizes (all <100nm) and morphologies (particles, fibers) of materials.



Objectives

The purpose of this project is to test the hypothesis that ultrafine uTiO2 surface area can be measured with specificity on heterogeneous particle-laden filter samples using fluorescence labeling. Our project will 1) develop a model for quantifying bulk ultrafine uTiO2 powder specific surface area using fluorescence labeling, 2) extend the model to evaluate surface area of aerosolized uTiO2 particles collected on filter media in a laboratory chamber, and 3) test the proposed model in ultrafine uTiO2 primary production workplaces. Our project specific aims are to:

1) Characterize a commercially-available bulk uTiO2 powder for use as a test material (density, morphology, total surface area, purity, and crystallinity),

2) Develop a technique for determining background surface area of filter media using nitrogen gas isotherms,

3) Determine the surface area of uTiO2-laden filter media using nitrogen gas isotherms, and

4) Determine the surface area of aerosolized uTiO2 particles collected on filter media in a laboratory chamber.

5) Additionally, we will evaluate the feasibility of determining uTiO2 surface area with specificity in heterogeneous aerosol samples using a fluorescing compound such as perylene diimide dye adsorbed to particle surfaces, and

6) Collect samples in a work place with uTiO2 exposures and analyze for surface area using the newly developed method and mass using mass spectroscopy on a single filter sample.



Mission Relevance

Inhalation exposure to ultrafine titanium dioxide (uTiO2) in the workplace may occur during primary production and manufacture of pharmaceuticals, cosmetics, personal care products (e.g., sunscreen), paints and coatings, and primary production of uTiO2. Available animal data indicates that ultrafine uTiO2 surface area is toxicologically more important for injury induction (e.g., inflammation) than is particle mass. The draft NIOSH Current Intelligence Bulletin for uTiO2 recommends measuring exposure in terms of surface area, but acknowledges that a method is lacking for measurement in the workplace. This project will be responsive to priorities for developing new methods that will allow measurement of particle surface area inhalation exposure as well as essential components for understanding hazard, i.e., measure, with specificity, uTiO2 surface area and mass levels in the same industrial hygiene sample. The purpose of this project is to measure uTiO2 surface area and mass in the same industrial hygiene sample.

This project will contribute to manufacturing strategic goal number 5: "reduce the number of respiratory conditions and diseases due to exposures in the manufacturing sector.

Additionally, this project will contribute to:

• RDR cross-sector Intermediate Goal (09PPRDRIG5.2): characterize respiratory exposures and measures used to reduce exposures, including engineering controls and respiratory protection, in work settings where engineered nanomaterials are produced or used.

• Activity/Output Goal (09PPRDRAOG5.2.1): develop partnerships and conduct field evaluations of facilities where nanomaterials are produced or used.

• EXA cross-sector Intermediate Goal 2.3 (09PPEXAIG2.3): Develop and evaluate new or improved methods for assessing exposure to workplace chemicals and occupational health stressors either singly or as mixtures, including both prospective and retrospective methods.

• Activity/Output 2.3.1 (09PPEXAAOG2.3.1): Development of new or improved methods to measure chemicals or other occupational hazards in the work environment.

• Activity/Output 2.3.2 (09PPEXAAOG2.3.2): Validation of these methods to provide and characterize their performance (specificity, sensitivity, accuracy, etc.) including publication in the NIOSH Manual of Analytical Methods.

• Activity/Output 2.3.3 (09PPEXAAOG2.3.3): Application of these methods to evaluate occupational exposure.

• EXA cross-sector Intermediate Goal 2.11 (09PPEXAIG2.11): Address critical exposure assessment needs in emerging areas such as nanotechnology for application of new approaches to both new and traditional industrial processes, and for emerging initiatives to substitute alternative (e.g., ostensibly more safe) chemical processes in areas where hazards have been identified.

• 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.

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

• Performance Measure 1.2 Within three years develop a baseline worker exposure assessment that identifies how exposures differ by work task or process.



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

 

NIOSH Program:

Manufacturing