Genotoxicity assessment of food-grade titanium dioxide

Food-grade titanium dioxide (E171 in Europe), which contains nanoscale particles (NPs), has been approved and used as a white pigment in various common foods. Concerns are growing over the use of E171 as a safe food additive. The purpose of the present research is to evaluate the genotoxicity of E171 using in vivo and in vitro testing systems. In vitro studies, Chinese hamster lung (V79) fibroblast cells were exposed to E171 at doses of 25, 50, 100, and 200 μg/mL. No gene mutations were observed after 24 h of treatment at any concentration using the hypoxanthine guanine phosphoribosyltransferase (Hprt) gene mutation assay. In vivo study, the healthy Kunming mice and SD rats were exposed to E171 through intragastric administration at doses of 250, 500 and 1000 mg/kg body weight every day for 15 days. Genotoxic potential of E171 was evaluated by micronucleus (MN) and comet assays in accordance with the OECD guideline. However, the results showed that E171 did not increase the frequency of bone marrow micronuclei or induce DNA strand breaks in rat liver cells at the doses used in this experiments. Under the conditions described in this report, E171 was concluded to be negative in these in vivo and in vitro genotoxicity tests. These findings suggest that E171 is not genotoxic, offering valuable data for risk assessment.