Genotoxicity of inhaled nanosized TiO(2) in mice.
ABSTRACT In vitro studies have suggested that nanosized titanium dioxide (TiO(2)) is genotoxic. The significance of these findings with respect to in vivo effects is unclear, as few in vivo studies on TiO(2) genotoxicity exist. Recently, nanosized TiO(2) administered in drinking water was reported to increase, e.g., micronuclei (MN) in peripheral blood polychromatic erythrocytes (PCEs) and DNA damage in leukocytes. Induction of micronuclei in mouse PCEs was earlier also described for pigment-grade TiO(2) administered intraperitoneally. The apparent systemic genotoxic effects have been suggested to reflect secondary genotoxicity of TiO(2) due to inflammation. However, a recent study suggested that induction of DNA damage in mouse bronchoalveolar lavage (BAL) cells after intratracheal instillation of nanosized or fine TiO(2) is independent of inflammation. We examined here, if inhalation of freshly generated nanosized TiO(2) (74% anatase, 26% brookite; 5 days, 4 h/day) at 0.8, 7.2, and (the highest concentration allowing stable aerosol production) 28.5 mg/m(3) could induce genotoxic effects in C57BL/6J mice locally in the lungs or systematically in peripheral PCEs. DNA damage was assessed by the comet assay in lung epithelial alveolar type II and Clara cells sampled immediately following the exposure. MN were analyzed by acridine orange staining in blood PCEs collected 48 h after the last exposure. A dose-dependent deposition of Ti in lung tissue was seen. Although the highest exposure level produced a clear increase in neutrophils in BAL fluid, indicating an inflammatory effect, no significant effect on the level of DNA damage in lung epithelial cells or micronuclei in PCEs was observed, suggesting no genotoxic effects by the 5-day inhalation exposure to nanosized TiO(2) anatase. Our inhalation exposure resulted in much lower systemic TiO(2) doses than the previous oral and intraperitoneal treatments, and lung epithelial cells probably received considerably less TiO(2) than BAL cells in the earlier intratracheal study.
- [show abstract] [hide abstract]
ABSTRACT: Effective interfacial adhesion between wood fibers and plastics is crucial for both the processing and ultimate performance of wood–plastic composites. Coupling agents are added to wood–plastic composites to promote adhesion between the hydrophilic wood surface and hydrophobic polymer matrix, but to date no coupling agent has been reported for PVC/wood-fiber composites that significantly improved their performance and was also cost-effective. This article presents the results of a study using chitin and chitosan, two natural polymers, as novel coupling agents for PVC/wood-flour composites. Addition of chitin and chitosan coupling agents to PVC/wood-flour composites increased their flexural strength by ∼20%, their flexural modulus by ∼16%, and their storage modulus by ∼33–74% compared to PVC/wood-flour composite without the coupling agent. Significant improvement in composite performance was attained with 0.5 wt% of chitosan and when 6.67 wt% of chitin was used. J. VINYL ADDIT. TECHNOL., 11:160–165, 2005. © 2005 Society of Plastics EngineersJournal of Vinyl and Additive Technology 11/2005; 11(4):160 - 165. · 1.11 Impact Factor
- Journal of Cellular Plastics - J CELL PLAST. 01/1983; 19(4):264-268.
- [show abstract] [hide abstract]
ABSTRACT: To increase the filler content in paper without sacrificing paper properties, clay−starch composites, made from a simple precipitation method, were used in papermaking. Compared to untreated clay, the clay−starch composite filled paper improved paper tensile strength up to 100−200%. Contrary to untreated clays that usually reduce the ZDT (z-directional tensile strength) of papers, the clay−starch composite actually increases the ZDT. The significant improvements in the paper strengths are attributed to the formation of a fiber−starch−filler sandwich structure, which avoids direct contact between filler and fiber. The specific shear bond strengths (expressed as specific bond strengths) between fillers and fibers were measured and used as the main variables for the modeling. It was also found that the fiber−fiber specific strength is weaker than the fiber−starch specific bond strength. The tensile strength (expressed as breaking length) was modeled by using a modified Page equation. The experimental results agreed very well with the modeling results.Industrial & Engineering Chemistry Research - IND ENG CHEM RES. 06/2007; 46(14).