NORA Manufacturing Sector Strategic Goals
927ZJLWa - Efficacy of NIOSH Method 0600 for Fine and Ultrafine Titanium Dioxide (NTRC)Start Date: 10/1/2009
End Date: 9/30/2011
Principal Investigator (PI)Name: Terri Pearce
Funded By: NIOSH
Primary Goals Addressed5.0 , 9.0
Secondary Goal AddressedNone
Attributed to Manufacturing100%
The NIOSH Strategic Plan for Nanotechnology Research identified measurement methods as a critical topic area. This project will test the hypothesis that the cyclone specified in NIOSH Method 0600 is capable of efficiently capturing TiO2 nanoaerosols and that the mass concentration can be matched to the particles counted with a real-time aerosol monitor sampling the same aerosol. The project will 1) use the cyclone specified in NIOSH Method 0600 to collect TiO2 nanoaerosols, 2) sample the nanoaerosols in parallel using the SMPS and person-wearable nephelometers, and 3) determine the comparability of the results by converting the measured values to calculated mass, number, and surface area concentration based upon the known particle size.
This project will assess the collection efficiency of the cyclone sampler specified in NIOSH Method 0600 when sampling fine and ultrafine titanium dioxide (TiO2) nanoaerosol. It will combine the filter-based results from Method 0600 with the results from real-time aerosol monitors to allow count and mass determinations to be used for calculating the nanoaerosol surface area. Such determination is possible for an aerosol that is well-characterized according to the particle number, material density, and mass of material suspended in a unit of air. The Laboratory Research Branch has acquired the facilities and expertise necessary for conducting such an assessment through a similar, recently-completed, experiment series evaluating direct-reading aerosol monitors over the operating temperature and relative humidity range specified by the instrument manufacturers. The current project will test the hypothesis that the cyclone specified in NIOSH Method 0600 is capable of efficiently capturing detectable amounts of TiO2 nanoaerosols and that the mass concentration can be matched to the number of particles counted with a real-time aerosol monitor sampling the same aerosol. The project goals and objectives will be: 1) use the cyclone specified in NIOSH Method 0600 to collect TiO2 nanoaerosols and determine the mass collected by weighing the filter and then sending it to the laboratory for TiO2 analysis, 2) sample the nanoaerosols in parallel using a scanning mobility particle sizer (SMPS) and person-wearable nephelometers, and 3) determine the comparability of the results obtained from the samplers to that from the real-time monitors by converting the measured values to calculated mass, number, and surface area concentration based upon the known particle size. In Year 1, a half-height manikin will be fitted with cyclone samplers and the nephelometer in the breathing zone and placed in a still air chamber. The SMPS will be placed to sample at the same height. The instruments and the samplers will be challenged with monodisperse TiO2 nanoaerosols of sodium fluorescein in specific size fractions representing the fine and ultrafine modes. The particle size will be confirmed by passing a portion of the aerosol through a SMPS prior to introduction to the chamber. In Year 2, the results of the evaluation will be reported in the peer-reviewed literature and provided as appropriate for updated the NIOSH TiO2 Current Intelligence Bulletin.
Objective: Provide information to be disseminated to the industrial hygiene community through the NIOSH Nanotechnology Research Center (NTRC) regarding the utility of NIOSH Method 0600 and real-time monitors for TiO2 nanoaerosol exposure assessment.
NIOSH research has shown that titanium dioxide (TiO2) possesses unique tumorigenic properties that are not a function of the chemical composition but rather of particle size and surface area. This finding caused NIOSH to recommend in the draft Current Intelligence Bulletin for TiO2 that surface area be the metric of exposure although NIOSH concedes that current methodology is not capable of such measurement in the workplace. Consequently, the NIOSH Strategic Plan for Nanotechnology Research identified measurement methods as one of 10 critical topic areas and stated that current methods for measuring mass of respirable particles in air should be evaluated for their applicability to measuring nanomaterials.