NORA Manufacturing Sector Strategic Goals
927Z1JV - Titanium Dioxide (TiO2) Nanoparticle Exposure Study
Principal Investigator (PI)
Primary Goal Addressed
Secondary Goals Addressed
Attributed to Manufacturing
Recent studies have suggested that ultrafine (< 0.1 µm) and fine (0.1 to 2.5 µm) particles of TiO2 may pose a health risk. While exposure data exists for larger TiO2 particles, no exposure data exists for ultrafine and fine TiO2 particles. The purpose of this study is to collect occupational exposure information for workers exposed to ultrafine and fine TiO2. The study objectives are:
1) to develop a strategy to measure exposure to ultrafine particles; 2) to characterize exposure to ultrafine and fine TiO2 for various jobs and tasks at various facilities manufacturing and using TiO2; and
3) evaluate a strategy for measuring workplace exposure to fine and ultrafine Ti02. The results of the study will be used by NIOSH in setting recommendations to protect workers exposed to ultrafine and fine TiO2.
Expected outputs include peer-reviewed journal articles and exposure guidance documents. Expected intermediate outcomes include the adoption of exposure sampling strategies for use in measuring exposure to nanoparticles.
Recent studies have suggested that ultrafine (< 0.1 µm) and fine (0.1 to 2.5 µm) particles of TiO2 may pose a health risk. TiO2 particles show a consistent dose-response relationship for pulmonary responses in rats, including persistent pulmonary inflammation and lung tumors—when dose is expressed as particle surface area. Traditional exposure monitoring uses gravimetric techniques when assessing exposure to airborne particles. Expressing exposure on a mass concentration basis (e.g. mg/m3) may not be the most appropriate metric for assessing health risk. While exposure data exists for larger TiO2 particles, no exposure data exists for ultrafine and fine TiO2 particles. Further, as nanotechnology is an emerging industrial and manufacturing field, exposure assessment for nanoparticles (ultrafine particles) is also emerging. Traditional exposure assessment techniques may not be feasible or appropriate.
The purpose of this study is to collect occupational exposure information to better inform NIOSH in setting recommendations to protect workers using ultrafine and fine TiO2.. The study objectives are: 1) characterize airborne TiO2 exposure metrics by job or process, 2) obtain quantitative estimates of exposure in workers to fine and ultrafine TiO2 particle sizes by relating the measured exposure metrics to worker exposure, and 3) evaluate a strategy for measuring workplace exposure to fine and ultrafine TiO2
Several facilities producing or using ultrafine and fine TiO2 will be recruited to participate in the study. Personal and area air samples and real-time particle number, size and surface area monitoring will be conducted. Air samples will be analyzed with gravimetric methods and electron microscopy for particle characterization. Various job tasks will be evaluated for exposure to TiO2.
In FY06, a study protocol was written and underwent peer review. Recruitment of companies and subjects and field work began in late FY06, and continued in FY07 and FY08. To date data has been collected from six facilities.
Field work and data analysis will continue in FY09.
The outcomes will be evaluated by:
1) Assessing the number of times the NIOSH CIB and Approaches documents are requested or downloaded.
2) Determining the number of times peer reviewed articles are cited.
3) Evaluating subsequent nanoparticle exposure literature to determine if the sampling methods developed for this study have been adopted by others.
Intermediate Goal 1.1 (09PPNAN1G1.1) Fate of nanomaterials in the work environment. Determine the key factors influencing the generation, dispersion, deposition, and re-entrainment of nanomaterials in the workplace, including the role of mixed exposures.
Titanium dioxide (TiO2), an insoluble white powder, is used extensively in many commercial products, including paint, cosmetics, plastics, paper, and food as an anti-caking or whitening agent. Production in the United States was an estimated 1.43 million metric tons per year in 2004. Approximately 2.7 million workers are potentially exposed to TiO2 in 42 standard industrial classifications (SICs) and 246 occupational groups. TiO2 is a poorly soluble, low toxicity (PSLT) dust, which has been used as a negative control in experimental studies investigating particle toxicity. However, recent animal studies have suggested that TiO2 particles in the ultrafine and fine size ranges may have a carcinogenic effect due to secondary mechanisms. NIOSH currently has no recommended exposure limit (REL) for TiO2 and classifies it as a potential occupational carcinogen. This recommendation was based on the observation of lung tumors (nonmalignant) in a chronic inhalation study in rats at 250 mg/m3 of fine TiO2. A 2-year inhalation study showed a statistically significant increase in lung cancer in rats exposed to ultrafine TiO2 at an average concentration of 10 mg/m3. TiO2 and other PSLT particles show a consistent dose-response relationship for pulmonary responses in rats, including persistent pulmonary inflammation and lung tumors—when dose is expressed as particle surface area.
Currently, no occupational exposure data exists for ultrafine TiO2 and little data exists for fine TiO2. Additional data and information are needed to assist NIOSH in evaluating the occupational safety and health issues of working with fine and ultrafine TiO2. Data are particularly needed on the airborne particle size distributions and exposures to ultrafines in specific operations or tasks. A critical research need is measurement of workplace airborne exposures to ultrafine TiO2 in facilities producing or using TiO2.
The purpose of this study is to collect occupational exposure information to better inform NIOSH in setting recommendations to protect workers using ultrafine and fine TiO2. The data will be used by the Education and Information Division (EID) to provide information for the Current Intelligence Bulletin (CIB) on TiO2, and the Approaches to Safe Nanotechnology Guidance Document.
This project addresses the Manufacturing Sector Strategic Goal 6: Reduce the incidence and prevalence of cancer due to exposures in the manufacturing sector.
Cancer, Reproductive, & Cardiovascular Diseases Cross-Sector - Cancer:
Intermediate Goal 1.1 (09PPCRCIG1.1); Activity/Output Goal 1.1.2. (09PPCRCAOG1.1.2); Intermediate Goal 1.3(09PPCRCIG1.3); Activity/Output Goal 1.3.2 (09PPCRCAOG1.3.2); Respiratory Diseases Cross-Sector: Intermediate Goal 5.2 (09PPRDRIG5.2); Activity/Output Goal 5.2.1 (09PPRDRAOG5.2.1); Exposure Assessment Cross-Sector: Intermediate Goal 1.1 (09PPEXAIG1.1); Activity/Output Goal 1.1.2 (O9PPEXAAOG1.1.3); Intermediate Goal 2.3 (09PPEXAIG2.3); Activity/Output Goal 2.3.1 (09PPEXAAOG2.3.1); Activity/Output Goal 2.3.2 (09PPEXAAOG2.3.2); Activity/Output Goal 2.3.3 (09PPEXAAOG2.3.3); Intermediate Goal 2.11 (09PPEXAIG2.11); Activity/Output Goal 2.11.1 (09PPEXAAOG2.4.1); Activity/Output Goal 2.11.2 (09PPEXAAOG2.4.2); Nanotechnology Cross Sector: Intermediate Goal 1.2 (09PPNANIG1.2)