Studying the ability of the food additive E171 (titanium dioxide) to induce gene mutations in bacteria

Introduction. Titanium dioxide in the Russian Federation is approved for use in the food industry, in the production of medicines and hygiene products. The food additive E171 is a mixture of micro- and nanoparticles of TiO₂. In 2010, IARC classified TiO₂ in nanoform as a probably carcinogenic to humans (Group 2B). In vitro and in vivo studies of the genotoxicity of titanium dioxide revealed contradictory results, indicating both the presence and absence of TiO₂ mutagenicity.

The aim of the work is to evaluate the mutagenicity of the food additive E171 in the Ames test using standard and modified protocols.

Materials and methods. The ability of food additive E171 (China) to induce reverse gene mutations in 5 strains of Salmonella typhimurium was studied under standard and modified conditions (cultivation of bacteria in the presence of methylated b-cyclodextrin (MCD) and/or pre-incubation for 1 hour in potassium phosphate buffer, pH 5.5 containing 10 mM NaCl and/or 3M MCD).

Results. A sample of food additive E171 based on rutile titanium dioxide does not induce gene mutations in S. typhimurium in standard experiments. Modification of the Ames test protocol (decrease of the incubation mixture pH, addition of 10 mM NaCl) revealed statistically significant dose-dependent effects in TA100, TA98, and TA97 strains under metabolic incubation conditions. However, the fold increase of the number of revertants in the experimental plates compared to the negative control was < 2.

Limitations. The research is limited to the mutagenicity assessment of food additive E171 (titanium dioxide) in the Ames test.

Conclusion. The evaluation of the mutagenicity of titanium dioxide in other in vitro and in vivo tests taking into account the size and shape of the particles, is necessary to resolve the issue of its genetic safety as a food dye. A full range of studies will be performed on other samples of titanium dioxide presented in the market of the Russian Federation.

Compliance with ethical standards. The study does not need the approval of the biomedical ethics committee or other documents.

Contribution:
Tsareva A.A. — collection of material, collection of literature data;|
Egorov O.V. — concept and design of research, collection of literature data, analysis of results, writing text;
Demidova Yu.V. — collection of material;
Ilyushina N.A. — concept and design of research, analysis of results, writing text.
All authors are responsible for the integrity of all parts of the manuscript and approval of the manuscript final version.

Conflict of interest. The authors declare no conflict of interest.

Acknowledgement. The study had no sponsorship.

Received: July 25, 2023 / Accepted: November 15, 2023 / Published: December 28, 2023