Titanium tetrachloride

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

Titanium tetrachloride reacts violently with water forming an insoluble precipitate (hydrolysis prodcut) therefore testing in an aqueous environment is not appropriate. Moreover both hydrolysis products were not mutagentic.

Endpoint conclusion

Endpoint conclusion:

no study available

Genetic toxicity in vivo

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

A classical Ames Test (Ogawa HI et al , 1986, reliability 2) and a Bacillus subtilis recombination assay (Kada T, Hirano K and Shirasu Y, 1980, reliability2) are available as tests for the mutagenicity of TiCl4. Due to the fast hydrolysis of TiCl4 it can beassumed that TiO2 particles and HCl were formed the latter of which was buffered by the used buffer system. So basically TiO2 was tested. Because of this behaviour of TiCl4 further testing of mutagenicity is scientifically unjustified. The hydrolysis products TiO2 and HCl have been shown not to be mutagenic:

Citation from the HCl dossier:

“Hydrochloric acid is not genotoxic in in vitro tests using bacterial or simple eukaryotic cells, while its effects on the pH of the medium precludes the possibility of testing in other in vitro non-bacterial systems. Hydrochloric acid rapidly dissociates almost completely in contact with water, releasing the chloride ion and the hydrogen ion which combines with water to form the hydronium ion. Both chloride and hydronium ions are normally present in the body, and mammals constantly secrete gastric juices, containing hydrogen ion concentrations equivalent to 0.17 N HCl, into the stomach. Further tests on this compound are therefore not necessary; this data requirement is not triggered.”

Citation from the TiO2 dossier:

“Titanium dioxide has been tested in bacterial reverse mutation assays, in vitro gene mutation and clastogenicity tests as well as in vivo. All tests show a negative response, thus titanium dioxide does not require classification for mutagenic properties.”

Short description of key information:

In vitro:Gene mutation (Bacterial reverse mutation assay / Ames test): negative with and without activation in all strains tested (similar to OECD TG 471)

Both hydrolysis products of TiCl4 (HCL and TiO2) that are formed immediately after water contact have been tested to be negative for a mutagenic potential.

Justification for classification or non-classification

Titanium tetrachloride will hydrolyse rapidly in contact with water. The conclusions that can be drawn from studies on bacteria are therefore limited to mutagenic effects in bacteria. As an insoluble precipitate is formed, the bioavailability of the substance to bacteria is questionable, and testing in an aqueous environment is not appropriate. From the absence of mutagenicity of the hydrolysis products TiO2 and HCl which are immediately formed in concat with water it can be deduced that TiCl4 does not exhibit mutagenic potential.