Registration Dossier

Data platform availability banner - registered substances factsheets

Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2012
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: GLP study performed without any deviation to the guideline

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2012
Report date:
2012

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
yes
Remarks:
only one concentration at saturation and one control were tested in a limit-test using a modified preparation of the test solution
GLP compliance:
yes (incl. QA statement)

Test material

Constituent 1
Chemical structure
Reference substance name:
Hafnium dioxide
EC Number:
235-013-2
EC Name:
Hafnium dioxide
Cas Number:
12055-23-1
Molecular formula:
HfO2
IUPAC Name:
hafnium dioxide
Test material form:
solid: particulate/powder
Remarks:
migrated information: powder
Details on test material:
Purity (as HfO2+ ZrO2)> 99.9%
Appearance: White powder
Expiry date: 21 November 2012

Sampling and analysis

Analytical monitoring:
yes
Details on sampling:
Samples for analysis were taken at the start and at the end of the test. Five samples were taken at the start both from the control and test item solution, while 2 samples were taken from each replicate (12 samples per group) both from the control and test item solution at the end of the test.
Samples (filtrated and acidified (10 ml sample + 1 ml HNO3)) were taken in plastic tubes, acidified with pure nitric acid.

Test solutions

Vehicle:
no
Details on test solutions:
Taking into account the very low solubility of the test item in the test medium and a possibility of phosphate depletion in the algae culture medium, induced by a complexation of phosphate by Hafnium, which was obtained by analytical results with the medium tested (80% depletion of phosphate), only one concentration at saturation and one control were tested in a limit-test using using WAF method. A supersaturated test item solution (nominally 100 mg/L) was prepared by dispersing/dissolving the amount of test item into the ultrapure water two days before the start of the experiment. This solution was shaken for about 24 hours at approximately 30°C and then equilibrated for about 24 hours at approximately 20°C. The non-dissolved test material was removed by filtration through a fine (0.22 µm) filter to give the 100 % v/v saturated solution.
After filtration the final test solution (in case of 1000 mL filtrate) was prepared in he following way: 20 mL of this filtrate was withdrawn from the flask and 20 mL of the mixed OECD I-IV solutions were added into the flask, so that 20 mL of the saturated solution was changed to 20 mL of the OECD salt solution containing I-IV OECD stock solutions. This way, the dilution of the saturated HfO2 solution was negligible, since 98% of the HfO2 was present in the solution. This solution was used for the test.

Test organisms

Test organisms (species):
Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)
Details on test organisms:
TEST ORGANISM
- Strain: 61.81 SAG (identical strains: CCAP 278/4; UTEX 1648; ATCC 22662)
- Source (laboratory, culture collection): The algae were supplied by the SAG: Collection of Algal Cultures, Inst. Plant Physiology, University of Göttingen, GERMANY. Cultured under standardised conditions (see OECD 201) in the Ecotoxicological Laboratory of CiToxLAB Hungary Ltd.
- Method of cultivation: The pre-culture was intended to give an amount of alga suspension suitable for the inoculation of test cultures. The pre-culture was incubated under the conditions of the study in an aerated Algal Growth Medium and used when still exponentially growing (after an incubation period of 3 days). The cell count of above culture was determined by microscopic method and this cell suspension was diluted with Algal Growth Medium to 107 cells/mL.

The initial cell number in the test cultures was 104 cells/mL.

Study design

Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
72 h

Test conditions

Test temperature:
The temperature was in the range of 22.8 – 23.0 °C measured in the flask and between 22.5 and 23.4 °C measured within the climate chamber.
pH:
The range of the pH was 7.90 – 7.91 at the start and
9.00 – 9.10 at the end of the study.
Nominal and measured concentrations:
Only one test concentration (100 % v/v saturated solution) at the solubility level of the test item in the test medium and one control group were tested
Details on test conditions:
TEST SYSTEM
The test was performed with six replicates per test concentration and six replicates in the control groups. Volumes of 100 mL algal suspension per replicate in 250 mL Erlenmeyer flasks were continuously shaken by a laboratory orbital shaker to keep algae in suspension. The flasks were covered with air-permeable stoppers.
The initial cell number in the test cultures was 104 cells/mL

GROWTH MEDIUM
- Standard medium used: yes

OTHER TEST CONDITIONS
- Light intensity and quality: The algal culture flasks were continuously illuminated. The light intensity at the position occupied by algal culture flasks during the test was about 8114 lux (equivalent to 109 E/m2/s), which was ensured with fluorescent lamps (with a spectral range of 400-700 nm). The differences in light intensity between the test vessels did not exceed  15 % and therefore provided equal conditions for each test vessel.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
The cell numbers were determined at 24, 48 and 72 hours after starting the test by manual cell counting using a microscopic method with a counting chamber.
Microscopic observation of the algal cells in each concentration and in the control was performed (at 24h, 48h and 72h) to detect any abnormal appearance of the algae.

TEST CONCENTRATIONS
Only one test concentration (100 % v/v saturated solution) at the solubility level of the test item in the test medium and one control group were tested

Results and discussion

Effect concentrationsopen allclose all
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
100 other: % saturated solution
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 100 other: % saturated solution
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
growth rate
Details on results:
The results of the statistical evaluation (based on 2 Sample t-Test; alpha=0.05) show that the 0-72 h average specific growth rate was not statistically significantly different from the untreated control value, accordingly the No Observed Effect Concentration (NOEC) was determined as 100 % v/v saturated solution. (see table 1 below)

The results of the statistical evaluation (based on 2 Sample t-Test; alpha=0.05) show that the 0-72 h areas were not statistically significantly different from the untreated control value, accordingly the No Observed Effect Concentration (NOEC) was determined as 100 % v/v saturated solution. (see table 2 below)

The results of the statistical evaluation (based on 2 Sample t-Test; alpha=0.05) show that the
0-72 h yield was not statistically significantly different from the untreated control value, accordingly the No Observed Effect Concentration (NOEC) was determined as 100 % v/v saturated solution. (see table 3 below)

Reported statistics and error estimates:
The section-by-section specific growth rates in the control cultures were assessed (calculated as the specific growth rates for each day during the course of the test (days 0-1, 1-2 and 2-3) and to demonstrate exponential growth for the entire study period.
The inhibition of alga growth was determined from the biomass (area under the growth curves, A), the average specific growth rate (r) and from the yield (y). Mean values and standard deviations were calculated for each concentration at the start, and at the end of the test using Excel for Windows software.
The EC50 values of the test item and their confidence limits were not calculated, due to the lack of toxic effects.

Statistical comparisons of biomass, average specific growth rates and yield in controls and in the treated groups were carried out using analysis of variance (ANOVA) and 2 Sample t-Test (alpha = 0.05) by TOXSTAT software.

Any other information on results incl. tables

Table 1:  Growth Rates (µ) and Percentage Inhibition of growth rate during the Test Period

Test group

Growth rate µ and % inhibition of µ

0–24 h

0–48 h

0–72 h

m

%

m

%

m

%

Control

0.0589

0.0

0.0607

0.0

0.0586

0.0

100 % v/v saturated solution

0.0553

6.0

0.0602

0.9

0.0586

0.1

Table 2:  Area under the Growth Curves (A) and Percentage Inhibition of A during the Test Period

Test group

Areas under the Growth Curves (A) and % inhibition of A

0–24 h

0–48 h

0–72 h

A

%

A

%

A

%

Control

38.0

0.0

286.0

0.0

1302.0

0.0

100 % v/v saturated solution

34.0

10.5

272.0

4.9

1278.0

1.8

Table 3:  Yield (Y) and Percentage Inhibition of Y during the Test Period

Test group

Yield (Y) and % inhibition of Y (0-72 h)

Y

%

Control

67.2

0.0

100 % v/v saturated solution

66.8

0.5

 

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
validity citeria:
The cell density in the control cultures was increased by a factor of 68.17 within three days.
The mean coefficient of variation for section-by-section specific growth rates
(days 0-1; 1-2; 2-3) in the control cultures was 11.24 %.
The coefficient of variation of average specific growth rates during the whole test period (day 0-3) in the control cultures was 0.95 %.
All validity criteria were met, therefore the study can be considered as valid.
Executive summary:

The effect of Hafnium dioxide test item was assessed on algal growth using the unicellular green alga Pseudokirchneriella subcapitata (Selenastrum capricornutum), over an exposure period of 72 hoursat the highest achievable concentrations of test item.

 

Under the conditions of this algal growth inhibition test the observed endpoints for the effect of Hafnium dioxide were the following:

 

The 72h EbC50value (biomass):        > 100 % v/v saturated solution(< 0.008 mg Hf/L)

The 72h ErC50value (growth rate):  > 100 % v/v saturated solution(< 0.008 mg Hf/L)

The 72h EyC50value(yield):               > 100 % v/v saturated solution(< 0.008 mg Hf/L)

 

The No-Observed Effect Concentration (NOEC):   100 % v/v saturated solution (< 0.008 mg Hf/L)

The Lowest Observed Effect Concentration (LOEC):   > 100 % v/v saturated solution (< 0.008 mg Hf/L)

 

Based on the results of this study, the test item Hafnium dioxidehadno toxic effect at saturation(< 0.008 mg Hf/L); the EC50results and the LOEC are higher than the solubility level of the test item in the test medium.