Daily used nanoparticles increases the incidence of cancer presented by Hanan Ramadan Hamad Mohamed Zoology Department Faculty of Science Cairo University

Nanoparticles Nanoparticles are the substances with size less than 100 nm, that making thier physical properties differe from those of their bulk material. Because of their unique size dependent physical and chemical properties, witnessed unprecedented growth in nanoparticles applications occurred. Now nanoparticles are now commercially available for industrial, medical and biological applications. All these applications potentially increased daily human exposure to nanoparticles and increased their risks

Titanium dioxide (TiO 2 ) nanoparticles TiO 2 nanoparticles have been widely used in a wide variety of applications due to their high stability, resistance, and photocatalytic properties. It is used in a variety of consumer products (e.g., toothpastes, sunscreens, cosmetics, food products), paints and pharmaceuticals, e.g. ultraviolet blockers, medications, and wastewater treatment.

Exposure routes

Nano-TiO2 toxicity These intensive uses of nano-TiO2 potentially increase daily human exposure to them and increasing their risks. To date, several studies have evidenced nano-TiO2 induced pulmonary inflammation, neurotoxicity, hepatotoxicity, nephrotoxicity, oxidative stress and distal organ involvement upon exposure to them (Zhou et al., 2003, stone et al., 2007 and Wang et al., 2007). Even nano-TiO2 induced genotoxicity and mutagenicity have been shown using different experimental systems (Rahman et al., 2002; Sadeghiani et al., 2005 and Kisin et al., 2007). But the question now whether these nano-TiO2 particles are removed or persisted in the tissue.

Aim of work Therefore this study was designed to investigate the bio-persistence of nano-TiO2 in mice tissue and its risks on cancer incidence

Ti accumulation DNA damage inductions using 1) Comet ass 2) Quantitative DNA frag. 3) Laddered DNA frag. SSCP to screen p53 mutations Histological examination Injected for five days with either H2o or TiO 2 Scarified after 24 hour, one and two weeks Experiments Oxidative stress

1-TiO 2 characterization

2- Titanium content

3-DNA damage induction using comet assay

Using quantitative DNA fragmentation

Laddered DNA fragmentation assay

4-SSCP analysis for p53 gene mutations

SSCP analysis

5-Histological examination

Leucocytic infiltrations Loss membrane permeability Necrosis ROS Increase cancer incidence

Conclusion Retention of orally administrated nano-TiO 2 in up to at least 2 weeks after stopping its administration Potentiation of nano-TiO 2 toxicity was evidenced by gradual dose- and time-dependent apoptotic DNA damage, histopathological changes, and oxidative stress inductions in mice gastric cells. Indeed, dose- and time-dependent mutation induction in the p53 gene revealed that nano-TiO 2 induced apoptosis is a p53 mediated process. Therefore, administration of even low nano-TiO 2 doses is accumulative due to its persisted accumulation therapy increases the incidence of cancer