Zirconium tetranitrate

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Non GLP and non guideline experiment. No analytics were performed. Basic data are given.

Data source

Reference

Reference Type:

publication

Title:

Zirconium toxicity assessment using Bacteria, Algae and Fish Assays

Author:

Couture et al.

Year:

1989

Bibliographic source:

Water, Air, and Soil Pollution, 47: 87-100

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

other: Blaise, C., Legault, R., Bermingham, N., Van Coillie, R., and Vasseur, E: 1986a, Tox. Assess. 1,261

Deviations:

not specified

Principles of method if other than guideline:

A miniaturized algal assay procedure using 96-well microtiter micro plates was performed.

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

Zirconium tetrachloride

EC Number:

233-058-2

EC Name:

Zirconium tetrachloride

Cas Number:

10026-11-6

IUPAC Name:

zirconium tetrachloride

Sampling and analysis

Analytical monitoring:

not specified

Test solutions

Vehicle:

not specified

Test organisms

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)

Details on test organisms:

TEST ORGANISM
- Common name: green algae
- Strain: ATCC 22662

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Test conditions

Hardness:

> 0.04 mg CaCO3/L

Salinity:

Not applicable

Nominal and measured concentrations:

96 hours exposure: eleven serial dilutions: 10, 5, 2.5, 1.25, 0.625, ... mg/L (nominal)

Details on test conditions:

TEST SYSTEM
- Test vessel: 96-well microtiter micro plates
- Initial cells density: 20000 cells/mL
- No. of vessels per concentration (replicates): 8
- No. of vessels per control (replicates): 8

GROWTH MEDIUM
- medium used: AAM algal assay medium

TEST MEDIUM / WATER PARAMETERS
- Culture medium different from test medium: No

OTHER TEST CONDITIONS
- Sterile test conditions: No data
- Adjustment of pH: No data

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: electronic particle counter

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2

Reference substance (positive control):

not specified

Results and discussion

Effect concentrations

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

2.6 mg/L

Nominal / measured:

nominal

Conc. based on:

other: Zirconium ions

Basis for effect:

growth rate

Remarks on result:

other: Mean EC50 value from 4 growth inhibition bioassays.

Details on results:

- Observation of abnormalities (for algal test): Yes, test substance caused precipitation of algal cells.
- Adherence to test vessels: Yes
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: No

Applicant's summary and conclusion

Validity criteria fulfilled:

not specified

Conclusions:

EC50 (96 hours) = 2.6 mg Zr/L (Couture et al., 1989)

Executive summary:

In a 96 hour acute toxicity study, cultures of Selenastrum capricornutum were exposed to the read across substance zirconium tetra chloride (CAS # 10026-11-6) at eleven nominal concentrations. The EC50 value based on growth inhibition was 2.6 mg Zr/L. A miniaturized algal assay procedure using 96-well microtiter micro plates was performed.

The test substance caused precipitation of algae cells and adherence of the cells to the walls of the test vessel. Furthermore Zirconium forms insoluble complexes with Phosphate (available in water), a well-known reaction of rare earth materials in the environment. The depletion of phosphate in the test medium during the test was clearly the reason for the inhibition of algal growth determined at test concentration. Thus, growth inhibition was due to a secondary effect (i.e. the complexation of the essential algal nutrient phosphate by the test item) which is not considered environmentally relevant.