Assessing the airborne titanium dioxide nanoparticles-related exposure hazard at workplace
Date Issued
2008
Date
2008
Author(s)
Chiang, Yu-Hui
Abstract
Titanium dioxide (TiO2) is a typical poorly soluble particles which was accounted for 70% of the total production volume of pigments worldwide. TiO2 is appied to produce cosmetics, sunscreens and catalytic agen in recently. High inhalation exposures occur in TiO2 production during packing, milling, mixed, and maintenance. International Agency for Research on Cancer (IARC) has recently classified TiO2 as possibly carcinogenic to humans in 2006. The purpose of this thesis is to combine the assessments of exposure and related effect to estimate the exceedence risks for workers in TiO2 manufacturing factories. This study used two datasets related to TiO2 dust concentrations in TiO2 plants in the United States (US) and Europe (EU), respectively,to explore the risk assessment. We apply the lognormal probabilistic model to fit particle size distribution data of airborne TiO2 in the TiO2 manufacturing factories. We estimate the inhalation risk of different size ranges of TiO2 natase and Rutile.in the TiO2 manufacturing factories by application physiologically based lung model (PB Lung Model). Three-parameter Hill model is used to reconstruct the dose-response profiles for polymorphonuclear leukocyte (PMN) elevation and lung tumor effects induced by TiO2 dust. The optimal fit of the lognormal probabilistic model (r2 = 0.95) resulting in a geometric mean (gm) of 24.81 nm with a geometric standard deviation (gsd) of 1.38. The optimal fit model (r2 = 0.91) for outside of factory with a gm of 42.71 nm and a gsd of 1.45. The results show the median effect (EC50) for PMN elevation is 0.11 m2 g-1 (n = 2.1, r2 = 0.88) and EC50 for lung tumor proportion is 1.15 m2 g-1 (n = 5.32, r2 = 0.85). The highest alveolar surface burden of packers in US factories are 0.1744 and 0.122 m2 for anatase and rutile, whereas that are 0.4 and 0.28 m2 for surface treatment workers in EU. The highest interstitial burden of packers in US were 0.9804 and 0.6856 m2 for anatase and rutile, whereas that were 2.25 and 1.57 m2 for surface treatment workers in EU. The exceedence risks curve of PMN elevation effect at risk = 0.5 of packers in US show the highest 67.33 and 35.9 fold of standard PMN counts for TiO2 anatase and rutile, whereas that are 84.94 and 71.28 fold for surface treatment workers in EU. The lung tumor risk results show 2×10-4 and 1.81×10-6 of lung tumor proportion for TiO2 anatase and rutile of surface treatment workers in EU. Then the lung tumor proportion are lower than 10-4 for all of the work categories in US and EU (except for surface treatment ) for anatase and rutile that unlikely induce lung tumor effect .
Subjects
Titanium dioxide
Specific surface area
Physiologically based lung model
Nanoparticle
nanotoxicology
risk assessment
SDGs
Type
thesis
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