Barium zirconium trioxide

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Reason / purpose for cross-reference:

reference to other study

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Batch # WON 2958 2018-0530, supplied 3rd October 2018
>99% (Single Component Substance). A Certificate of Analysis was supplied for this test material which stated that it contained 54.49% BaO and 44.68% Zr02
Stored in original container at a temperature of 20 ± 2 deg C

Analytical monitoring:

yes

Remarks:

Analysis was carried out at an external laboratory on solutions supplied by Cheshire Eco Solutions

Details on sampling:

The WAFs appeared cloudy. A 50ml sub-sample of each test concentration including the control test media was taken and filtered through 0.45 micron filtered prior to storage in the dark at room temperature in the Daphnia test lab at 20 +/- 2C. Samples were supplied to Thermograde who arranged ICP analysis of the filtered sub samples for soluble Ba and Zr

Vehicle:

yes

Remarks:

ISO Freshwater media (Cheshire Eco Solutions SOP 1.1) batch number ISO FW/18004.

Details on test solutions:

The sample was found to be insoluble in freshwater and appropriate Water Accommodated Fractions (WAF's) were prepared in the dilution media.
Test material preparation: Water Accommodated Fractions (WAF's) containing concentrations of 100.0, 177.8, 316.2, 562.3 and 1000.0 mg/l BARIUM ZIRCONATE were prepared in dilution media. After being stirred overnight and then left to settle for four hours the WAF's were slightly cloudy with settled white powder, both increasing with each concentration. 20ml from the central portion of each was then removed to be used as the test concentration.

Test organisms (species):

Daphnia magna

Details on test organisms:

Daphnia magna
Hatched from ephippia supplied by Microbiotests Inc., Belgium (Suppliers Batch number DM290118).
Test animals were assigned a batch number of DM18008.
At the start of the test the animals were <24 hours old.

It should be noted that the Daphnia magna ephippia used to produce the test organisms in this study were slightly beyond the supplier recommended use by date when hatching was initiated. However they hatched normally within 72 hours at 20-220C and produced acceptable control immobilisation of 0% after 48 hours exposure during this study. Therefore it is the opinion of the Study Director that they were suitable for use in this study.

Test type:

static

Water media type:

freshwater

Remarks:

ISO Freshwater media

Limit test:

yes

Total exposure duration:

48 h

Post exposure observation period:

Animals were observed after 24 and 48 hours exposure for mobility

Hardness:

not required - standard ISO freshwater media

Test temperature:

20 - 22 deg C

pH:

Test material Concentrations(mg/I) = 0, 100, 177.8, 316.2, 562.3, 1000.0
pH
Start End
7.54 7.48
7.96 7.99
7.90 7.88
8.04 7.91
8.01 7.90
8.50 7.93

Dissolved oxygen:

Test material Concentrations(mg/I) = 0, 100, 177.8, 316.2, 562.3, 1000.0
Dissolved Oxygen (% ASV)
Start End
100.0 98.2
94.7 95.5
92.8 95.6
93.0 95.7
93.2 95.1
92.9 94.8

Salinity:

not applicable

Nominal and measured concentrations:

There was No Observed Effect at the highest concentration (1000 mg/l) so just the control sample and the 1000.0 mg/l were analysed. Barium zirconate is insoluble but there is a small amount of barium carbonate impurity which is sparingly soluble. The values obtained for the Control sample (no added substance) and the 1000 mg/l sample were as follows;
Control Ba = <0.1 mg/l; Control Zr = <0.1 mg/l
1000 mg/l BaZrO3 - Ba = 0.4 mg/l, Zr = <0.1 mg/l

Details on test conditions:

Four replicates of 50 ml of each test material concentration, together with four replicates of the control media were prepared. Five animals were added to each test vessel and exposures conducted under static conditions for 48 hours at a nominal temperature of 20 ± 2 0 deg C.

Reference substance (positive control):

yes

Remarks:

The Potassium Dichromate reference toxicant test results for the batch of Daphnia magna ephippia used in this study were within the acceptability range defined in ISO 6341

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Key result

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Key result

Duration:

48 h

Dose descriptor:

LOEC

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

After 48 hours exposure to BARIUM ZIRCONATE, the EC50 value was calculated to be >1000.0 mg/I . The 24 hour EC50 value was also calculated to be > 1000.0 mg/I . The highest concentration of test material producing No Observable Effect (NOEC), was determined to be 1000.0 mg/I in this study. The concentration of test material producing the Lowest Observable Effect (LOEC), was determined to be >1000.0 mg/I in this study.

Validity criteria fulfilled:

yes

Conclusions:

In this study a sample of BARIUM ZIRCONATE was assessed for potential toxic effects on the freshwater invertebrate Daphnia magna in a static test over 48 hours
Water Accommodated Fractions (WAFs), containing BARIUM ZIRCONATE were prepared over the range 100.0 to 1000.0 mg/I . A number of Daphnia magna were exposed to the test concentrations in order to determine the concentration which immobilised 50% of the neonates over 48 hours (EC50).
The lowest concentration of test material producing 100% immobilisation could not be determined in this study. The highest concentration of test material producing no immobilisation in this study was a test concentration of 1000.0 mg/l. There was no evidence of a dose response in this study.

Description of key information

The lowest concentration of test material producing 100% immobilisation could not be determined in this study. The highest concentration of test material producing no immobilisation in this study was a test concentration of 1000.0 mg/l nominal. There was no evidence of a dose response in this study.

The level of barium ions in solution for the 1000 mg/l test concentration was determined to be 0.4 mg/l.

The water solubility of this material is very low at around 5 mg/l as Ba2+ ions at a pH of ~ 8.0, and is likely to be due to barium carbonate impurity rather than the solubility of the barium zirconate ion itself.

Any effect that may have been seen on the daphnia is likely to be associated with Ba ions in solution as a result of dissolution of barium carbonate impurity under the conditions of the test, and in this case, the Ba ion concentration was very low so no effect seen.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

1 000 mg/L