Barium titanium trioxide

Endpoint summary

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

There is a reliable study available to assess the potential of the analogous test substance for skin sensitisation.

For read-across barium chloride is adopted as it is also an inorganic barium salt whose relevant toxicological nature depends on the common cation barium whereas the toxicological nature of the anion is negligible. The substances differ in solubility. Barium chloride is soluble while barium titanium trioxide is slightly soluble. But this difference is considered as negligible as it is supported by the absence of any adverse findings in acute toxicity for the analogue substance. In conclusion, read-across for the endpoint skin sensitisation is justified.

Skin sensitisation

A local Lymph Node assay according to OECD guideline 429 was performed to assess the skin sensitization potential of the analogous test substance Barium dichloride dihydrate (CAS no 10326-27-9) (purity: 100.6 %) (Stitzinger, 2010).

A preliminary irritation study was conducted in order to select the highest test substance concentration to be used in the main study. There, no irritation and no signs of systemic toxicity were observed in any of the animals examined with a solution with the analogous test substance Barium dichloride dihydrate of 10% and 25%. Based on these results, the highest test substance concentration selected for the main study was a 25 % concentration.

Five female CBA mice were epidermal treated with the test substance in the concentrations 5, 10 and 25 % at the dorsal surface of both ears on day 1. The application procedure was repeated on day 2 and 3. On day 6 (3)H-methyl thymidine was injected via the tail vein for radioactivity measurements. After approximately 5 hours the draining (auricular) lymph node of each ear was excised and the relative size of the nodes (as compared to normal) was estimated by visual examination and abnormalities of the nodes and surrounding area were recorded. The nodes were pooled for each animal.

No irritation of the ears was observed for any of the animals treated with the test substance or for vehicle control animals. The majority of auricular lymph nodes were considered normal in size, except for the enlarged nodes in the majority of animals treated with 25 % of the test substance.

Radio-labelled lymph node cells (LNC) were counted to calculate the Stimulation Index (SI) for each group. The SI is the ratio of the DPM (Disintegrations Per Minute )/group compared to DPM/vehicle control group. If the results indicate a SI ≥ 3, the test substance may be regarded as a skin sensitizer, based on the test guideline. The resulted SI indices were: 1.3 +/- 0.3 at 5 % test substance concentration; 1.5 +/- 0.3 at 10 % test substance concentration and 1.2 +/- 0.3 at 25 % test substance concentration.

Since there was no indication that the test substance elicits an SI ≥ 3 when tested up to 25 %, Barium Chloride Di-Hydrate was considered not to be a skin sensitizer under the test conditions chosen.

Migrated from Short description of key information:
Skin sensitisation
read-across, in vivo, mouse: not sensitising (GLP, OECD 429; Stitzinger, 2010)

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information:

Migrated from Short description of key information:
respiratory sensitisation
No data available but experience from the handling of titanium trioxide in industrial and commercial surroundings give no indication that the substance is sensitising via the respiratory route.

Justification for classification or non-classification

Classification, Labeling, and Packaging Regulation (EC) No. 1272/2008:

Based on the results, the classification of the test substance for skin sensitization under Regulation 1272/2008 is not warranted.