Barium zirconium trioxide

Endpoint summary

Description of key information

Studies on the acute oral toxicity of barium zirconate revealed that they are of relatively low toxicity, which may be due in part to the insolubility of this material. However, rats given barium zirconate at levels in the 3.0 and 6.0 g/kg range finding tests all died and so testing at lower levels up to 5 g/kg were carried out.

In those instances where a lethal dose was administered the majority of the animals died within 12 hours,although some survived for as long as 36 hours. The gross pathological and histological examinations carried out on these animals showed no characteristic changes.

The analysis for the barium zirconate that was used for these tests appears to have had some barium carbonate impurity. Barium carbonate is soluble and exhibits acute oral toxicity in the rage 1600 - 2000 mg/kg/bw. It may be that the fact that this impurity was present was the cause of the acute oral toxicity in the barium zirconate tested.   Nevertheless, the barium zirconate substance under registration also contains low level barium carbonate impurity albeit not at the same high level as the test material in this study report. However, a precautionary approach has been taken in the absence of any further available oral toxicity data and this substance has been classified as poentially harmful by ingestion.

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records

Reference

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Remarks:

The study is old (1963) but has been done to accepted oral toxicity methods and sufficient detail is given.

Qualifier:

equivalent or similar to guideline

Guideline:

EPA OPP 81-1 (Acute Oral Toxicity)

Deviations:

not applicable

Principles of method if other than guideline:

The acute oral and intraperitoneal toxicity tests were carried out with male white rats of the Wistar strain weighing about 200 grams.
The compounds were administered as a suspension in corn oil, measured amounts of which were given by means of a calibrated syringe and stomach tube for oral toxicity tests, and with an 18 gauge needle for the intraperitoneal toxicity tests.
Range-finding doses having been previously carried out, the LD50, values were determined by administering the two materials to four groups of six rats in amounts which increased progressively by a factor of two. The LD50 doses were calculated from the tables published by Weil.
All animals which died as a result of this acute toxicity testing were autopsied and a histological examination carried out. The survivors were kept on a normal diet for a period of one month to determine what delayed effects, if any, might arise.

GLP compliance:

no

Remarks:

Work done prior to GLP standard being required

Test type:

acute toxic class method

Specific details on test material used for the study:

Barium zirconate (BaZrO,) is a fine grayish-white powder which is insoluble in water.
The average particle size of the commercial product is 0.5 to 3.0 microns.
A typical chemical analysis by weight is: 40.18% ZrO,; 50.92% BaO; 0.25% TiO,; 0.10% CaO; 0.05% MgO; 0.32% SrO; 1.70% SiO,; 0.11% A1,0,; 0.10% Fe,O,; 0.05% K,O; 0.11% Na,O; 0.001% CuO; 0.04% P,O,; 0.33% SO,; 5.11% CO2 and 5.69% ignition loss.
The presence of 5.11% CO2 and an ignition loss of 5.69% may suggest that this sample contained barium carbonate as an impurity at a level between 1 - 10 %

Species:

rat

Strain:

Wistar

Sex:

male

Details on test animals or test system and environmental conditions:

male white rats of the Wistar strain weighing about 200 grams

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on oral exposure:

The compounds were administered as a suspension in corn oil, measured amounts of which were given by means of a calibrated syringe and stomach tube for oral toxicity tests.

Doses:

Oral doses of 0.75, 1.5, 3.0 and 6.0 g/kg of body weight were given as range-finding doses.
Rats given zirconium lactate survived, whereas those receiving barium zirconate in excess of 1.5 g/kg died.
Groups of six rats were then given graduated doses of 0.625, 1.25, 2.5, and 5.0 g/kg of barium zirconate

No. of animals per sex per dose:

Six

Control animals:

not specified

Preliminary study:

Yes - Oral doses of 0.75, 1.5, 3.0 and 6.0 g/kg of body weight were given as range-finding doses. Rats given barium zirconate in excess of 1.5 g/kg died

Key result

Sex:

male

Dose descriptor:

LD50

Effect level:

1 980 mg/kg bw

Based on:

test mat.

Interpretation of results:

Category 4 based on GHS criteria

Remarks:

LD50 = 1980 mg/kg/bw

Conclusions:

Studies on the acute oral toxicity of barium zirconate revealed that they are of relatively low toxicity, which may be due in part to the insolubility of this material.
However, rats given barium zirconate at levels in the 3.0 and 6.0 g/kg range finding tests all died and so testing at lower levels up to 5 g/kg were carried out.
In those instances where a lethal dose was administered the majority of the animals died within 12 hours,although some survived for as long as 36 hours. The gross pathological and histological examinations carried out on these animals showed no characteristic changes.
The analysis for the barium zirconate that was used for these tests appears to have had some barium carbonate impurity. Barium carbonate is soluble and exhibits acute oral toxicity in the rage 1600 - 2000 mg/kg/bw. It may be that the fact that this impurity was present was the cause of the acute oral toxicity in the barium zirconate tested.
Nevertheless, the barium zirconate substance under registration also contains low level barium carbonate impurity albeit not at the same high level as the test material in this study report. However, a precautionary approach has been taken in the absence of any further available oral toxicity data and this substance has been classified as poentially harmful by ingestion.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LD50

Value:

1 980 mg/kg bw