Genotoxicity of the food additive E171, titanium dioxide, in the plants Lens culinaris L. and Allium cepa L.

E171 (titanium dioxide, TiO₂), an authorized foods and beverage additive, is also used in food packaging and in pharmaceutical and cosmetic preparations. E171 is considered to be an inert and non-digestible material, not storable in animal tissues, but the possible presence of TiO₂ nanoparticles (NP) may present a risk to human health and the environment. We determined the presence of 15% TiO₂ NP in a commercial E171 food additive product, by electron microscopy. The biological effects of E171 were assessed in Lens culinaris and Allium cepa for the following endpoints: percentage of germination, root elongation, mitotic index, presence of chromosomal abnormalities, and micronuclei. The results indicated low phytotoxicity but dose-dependent genotoxicity. We also observed internalization of TiO₂ NP and ultrastructural alterations in the root systems.