Barium titanium trioxide

Endpoint summary

Additional information

There are reliable studies on the substance itself and read-across studies available to assess the potential of the test substance for aquatic toxicity.

For read-across barium chloride is adopted as it is also an inorganic barium salt whose relevant ecotoxicological nature depends on the common cation barium whereas the ecotoxicological 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 aquatic toxicity is justified.

 

- Short-term toxicity to fish:

In a short-term toxicity study to fish with the analogous test substance barium chloride dehydrated (CAS 10326-27-9) Danio rerio fishes were exposed for 96 hours in fresh water under static conditions to the nominal dose levels 117 and 178 mg/L test item. This corresponds to 66 and 199 mg/L Ba.

The LC50 (96 h) based on measured concentrations in non-filtered test solutions was higher than 97.5 mg/L Ba.

The LC50 (96 h) based on nominal concentrations was higher than 152 mg/L BaCl2.

Based on the results with the analogous test substance the LC50 (96 h) of barium titanium trioxide based on measured concentrations is therefore higher than 165,56 mg/L (calculated from its molecular weight) and based on nominal concentrations of the analogous test substance higher than170,22 mg/L BaTiO3 under the test conditions chosen.

 

- Long-term toxicity to fish:

In Annex IX of Regulation (EC) No 1907/2006, it is laid down that long-term toxicity testing in fish shall be proposed by the registrant if the chemical safety assessment indicates the need to investigate further the effects on fish. According to Annex I of this regulation, the chemical safety assessment triggers further action when the substance or the preparation meets the criteria for classification as dangerous according to Directive 67/548/EEC or Directive 1999/45/EC or is assessed to be a PBT or vPvB.

The hazard assessment of barium titanium trioxide reveals neither a need to classify the substance as dangerous to the environment, nor is it a PBT or vPvB substance, nor are there any further indications that the substance may be hazardous to the environment.

Therefore, and for reasons of animal welfare, a long-term toxicity testing in fish is not required.

 

- Short-term toxicity to aquatic invertebrates:

In a short-term toxicity study to aquatic invertebrates with the analogous test substance barium dichloride(CAS 10361-37-2) in Daphnia magna the LC50 was estimated to be 14500 µg/L based on metal ion after an exposure time of 48 hours in static freshwater. For barium titanium trioxide this would result in a LC50 of 24.62 mg/L. Concerning that barium titanium trioxide can be considered as stable and that it is slightly soluble in water biodegradation does not occur as barium titanium trioxide is inorganic. Bioaccumulation, expressed by determination of log Pow, as well as adsorption/desorption behaviour are not applicable as the determination of the partition coefficient n-octanol/water (log Pow = P-value) applies only for organic substances.

Therefore, it is expected that barium titanium trioxide does not show short-term toxicity to aquatic invertebrates.

 

- Long-term toxicity to aquatic invertebrates:

In a long-term toxicity study to aquatic invertebrates with the analogous test substance barium dichloride (CAS 10361-37-2) in Daphnia the EC16 for reproduction was estimated to be 5800 µg/L based on metal ion after an exposure time of 21 days in semi-static freshwater. According to ECHA methodology, the EC16 (i.e., effects situated between 10 and 20%) can be used to estimate a NOEC-value; ECx (10% < x < 20%) /2 = NOEC. In this case, a NOEC of 2.9 mg/L for Ba2+ has been derived. This would mean a NOEC of 4.9 mg/L for Barium titanium trioxide (calculated from its molecular weight).

Therefore, it is expected that the test substance barium titanium trioxide does not show long-term toxicity to aquatic invertebrates as the NOEC is > 1 mg/L under the conditions chosen.

 

- Toxicity to aquatic algae and cyanobacteria:

In a limit test toxicity study to aquatic algae (Pseudokirchnerella subcapitata) with the test substance barium titanium trioxide a concentration of 100 mg/L of the test substance was exposed to the algae for 48 hours. The EC50 of the test substance is > 100 mg/L as no inhibition effect on the growth of the algae used for the test was observed.

 

- Toxicity to microorganisms:

In a toxicity study to microorganisms with the analogous test substance barium chloride dihydrate (CAS 10326-27-9) in activated sludge of a predominantly domestic sewage the nominal test item concentrations of 10, 32, 100, 320, and 1000 mg BaCl2/L showed no statistically significant inhibitory effect on the respiration rate of the test system.Thus, the results of this study demonstrate that the test item did not inhibit respiration of activated sludge at a concentration up to 1000 mg/L. Toxic effect levels (EC20, EC50 and EC80) are therefore greater than 1000 mg BaCl2/L. The No Observed Effect Concentration (NOEC) is ≥ 1000 mg BaCl2/L, and hence the Lowest Observed Effect Concentration (LOEC) is > 1000 mg BaCl2/L under the test conditions chosen. Based on the results with the analogous test substance the EC50 and NOEC of barium titanium trioxide are therefore expected to be higher than 1119 mg/L (calculated from its molecular weight).