Updated assessment of the genotoxic potential of titanium dioxide based on reviews of in vitro comet, mode of action and cellular uptake studies, and recent publications.
David Kirkland, Arne Burzlaff, Andreas Czich, Shareen H Doak, Paul Fowler, Stefan Pfuhler, Leon F Stankowski
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引用次数: 0
Abstract
In 2021 the European Food Safety Authority (EFSA) concluded that "A concern for genotoxicity of TiO2 particles that may be present in E 171 could therefore not be ruled out.". A detailed review of the genotoxicity of titanium dioxide (TiO2) was subsequently published by Kirkland et al. (2022) using a comprehensive weight of evidence (WoE) approach in which test systems and endpoints were allocated different levels of relevance. At that time only 34 publications met the reliability and quality criteria for being most relevant in the evaluation of genotoxicity, and based on these it was concluded that the existing evidence did not support a direct DNA damaging mechanism for TiO2. Recently a number of regulatory opinions have been published, in which papers were cited that described in vitro DNA damage (mainly comet), mode of action, and cellular uptake studies that were not discussed in Kirkland et al. (2022). Furthermore, a number of additional papers have been published recently or have been identified from the regulatory opinions as a result of using extended search criteria. A total of 70 publications not previously reviewed in Kirkland et al. (2022) have been reviewed here, and again show that the published data on the genotoxicity of TiO2 are inconsistent, often of poor quality, and in some cases difficult to interpret. The cellular uptake studies show some evidence of cytoplasmic uptake, particularly in cells treated in vitro, but there is no convincing evidence of nuclear uptake. In terms of genotoxicity, the conclusions of Kirkland et al. (2022) that existing evidence does not support a direct DNA damaging mechanism for titanium dioxide (including nano forms), and that the main mechanism leading to TiO2 genotoxicity is most likely indirect damage to DNA through generation of reactive oxygen species (ROS), are still valid.
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Regulatory Toxicology and Pharmacology publishes peer reviewed articles that involve the generation, evaluation, and interpretation of experimental animal and human data that are of direct importance and relevance for regulatory authorities with respect to toxicological and pharmacological regulations in society. All peer-reviewed articles that are published should be devoted to improve the protection of human health and environment. Reviews and discussions are welcomed that address legal and/or regulatory decisions with respect to risk assessment and management of toxicological and pharmacological compounds on a scientific basis. It addresses an international readership of scientists, risk assessors and managers, and other professionals active in the field of human and environmental health.
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