Titanium Dioxide Nanoparticles Induce DNA Damage in Peripheral Blood Lymphocytes from Polyposis coli, Colon Cancer Patients and Healthy Individuals: An Ex Vivo/In Vitro Study

Titanium dioxide (TiO₂), in bulk and nanomaterial format, has been used as a whitening and brightening agent in pigments, paints, plastics and paper, but also as an ingredient of pharmaceutical products and increasingly as a food additive. TiO₂ nanoparticles (NPs) have been also reported in soil, vegetables and the human body suggesting that the gastrointestinal tract may be a very important route of exposure. This study determined if TiO₂ nanoparticles differentially affected gastrointestinal patients and healthy volunteers. The cytotoxic and genotoxic potential of TiO₂ NPs have been examined in peripheral blood lymphocytes in polyposis coli and colon cancer patients as well as healthy individuals. Physicochemical characterisation of TiO₂ NPs involved: Dynamic light scattering (size distribution from 104 nm in ddH₂O to 1303 nm in RPMI), Zeta potential (−28.7 mV) and SEM (average size 34 nm) measurements. Cells were exposed to nanoparticle concentrations ranging from 10 to 80 μg/ml. Techniques used were: The Comet assay, the Micronucleus assay and the Micronucleus assay with fluorescent in situ hybridization (FISH). Concentration dependent effects of TiO₂ NPs in both patient groups and healthy individuals were observed in the Comet assay, when OTM and % Tail DNA parameters were examined. Also the frequency of micronuclei (MN) in binucleated cells was increased in a concentration-dependent manner. Experiments revealed that polyposis coli and colon cancer patients had a higher level of DNA damage in the Comet assay and a higher number of MN than healthy individuals. Thus, TiO₂ NPs induced concentration-dependent increases of damage, regardless of confounding factors, differentially in patients and healthy controls.