Genotoxic effects of nanosized and fine TiO2

Abstract

<jats:p> The in-vitro genotoxicity of nanosized TiO<jats:sub>2</jats:sub> rutile and anatase was assessed in comparison with fine TiO<jats:sub>2</jats:sub> rutile in human bronchial epithelial BEAS 2B cells using the single-cell gel electrophoresis (comet) assay and the cytokinesis-block micronucleus test. BEAS 2B cells were exposed to eight doses (1—100 μg/cm<jats:sup>2</jats:sup>) of titanium(IV) oxide nanosized rutile (&gt;95%, &lt;5% amorphous SiO<jats:sub>2</jats:sub> coating; 10 × 40 nm), nanosized anatase (99.7%; &lt;25 nm), or fine rutile (99.9%; &lt;5 μm) for 24, 48, and 72 h. Fine rutile reduced cell viability at lower doses than nanosized anatase, which was more cytotoxic than nanosized rutile. In the comet assay, nanosized anatase and fine rutile induced DNA damage at several doses with all treatment times. Dose-dependent effects were seen after the 48- and 72-h treatments with nanosized anatase and after the 24-, 48- (in one out of two experiments), and 72-h treatments (one experiment) with fine rutile. The lowest doses inducing DNA damage were 1 μg/cm<jats:sup>2</jats:sup> for fine rutile and 10 μg/cm<jats:sup> 2</jats:sup> for nanosized anatase. Nanosized rutile showed a significant induction in DNA damage only at 80 μg/cm<jats:sup>2</jats:sup> in the 24-h treatment and at 80 and 100 μg/ cm<jats:sup>2</jats:sup> in the 72-h treatment (with a dose-dependent effect). Only nanosized anatase could elevate the frequency of micronucleated BEAS 2B cells, producing a significant increase at 10 and 60 μg/cm<jats:sup> 2</jats:sup> after the 72-h treatment (no dose-dependency). At increasing doses of all the particles, MN analysis became difficult due to the presence of TiO<jats:sub>2</jats:sub> on the microscopic slides. In conclusion, our studies in human bronchial epithelial BEAS 2B cells showed that uncoated nanosized anatase TiO<jats:sub>2</jats:sub> and fine rutile TiO<jats:sub>2</jats:sub> are more efficient than SiO<jats:sub> 2</jats:sub>-coated nanosized rutile TiO<jats:sub>2</jats:sub> in inducing DNA damage, whereas only nanosized anatase is able to slightly induce micronuclei. </jats:p>

In vitro cytotoxicity and genotoxicity studies of titanium dioxide (TiO2) nanoparticles in Chinese hamster lung fibroblast cells

“…In the present study, we focused on the effects of one type of NP, nano-TiO 2 , with respect to its different physico-chemical properties, including particle surface modification. The physico-chemical characteristics of the TiO 2 test samples (shown in Table 1) were consistent with findings of others (Falck et al, 2009;Limbach et al, 2005). Particles with smaller sizes possess larger surface areas, have a stronger tendency to agglomerate in medium, and interact more with biomolecules such as proteins and DNA in biological environment.…”

“…Similarly, an in vivo study has shown the induction of DNA breakage in mice cells after exposure to P25-TiO 2 in drinking water (Trouiller et al, 2009). In human bronchial epithelial cells exposed to TiO 2 particles, the oxidative DNA damage was shown to be higher in nano-sized anatase compared to its larger counterparts (Gurr et al, 2005), and nano-sized anatase was more toxic than nano-sized rutile (Falck et al, 2009). Our genotoxicity findings agree with earlier studies in the induction of DNA damage in cells after exposure to nano-TiO 2 , and a stronger induction was observed in nano-sized anatase compared to rutile.…”

“…Nano-TiO 2 can induce lung cancer in rats, and toxicity in human bronchial cells (Falck et al, 2009;Pott and Roller, 2005). In the present study, hamster lung fibroblast cells were chosen to investigate the toxicity of TiO 2 particles because the lung is the primary target organ of TiO 2 particle toxicity (Baan et al, 2006;Rothen-Rutishauser et al, 2006), using concentrations that were relevant to those that induced toxicity in earlier in vivo studies.…”

“…The photocatalytic activity and cytotoxicity of the anatase nano-TiO 2 are higher than that of the rutile form (Kakinoki et al, 2004;Sayes et al, 2006). Similarly, several studies suggested that lung inflammation and consequently cancer in rats could be induced after inhalation and intratracheal instillation of TiO 2 nanoparticles, with stronger inflammogenic activity in comparison with its micron-sized counterpart (Donaldson et al, 2002;Falck et al, 2009;Renwick et al, 2004).…”

The potential health risk of titania nanoparticles

“…Anatase TNPs cause dose-related oxidative DNA damage and micronucleus (MN) formation in A431 and BEAS 2B cells [60,96], as well as sister chromatid exchange at a higher dosage [97]. IMR-90 cells were more sensitive to TNP, showing genotoxicity (ROS-induced DNA adduct formation) [98].…”