Aluminium cerium lutetium oxide

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

January 16, 2017 - January 20, 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)

Version / remarks:

July 28, 2011

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Version / remarks:

August 24, 2009

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Concentrations: 6.25, 12.5, 25, 50, 100, and the control
- Sampling method: For the determination of the stability of the test item under the test conditions and of the maintenance of the test item concentrations during the test period, triplicate samples from the test media of all test concentrations and the control (containing algae) were taken at the end of the test (after the 72 hours test period) after pooling the contents of the test beakers of each treatment. One additional sample of the blank control was taken at test start and test end without any sample treatment.
- Sample storage conditions before analysis: All samples were stored in a fridge (+4 ± 4°C) immediately after sampling, and were stored in a fridge.

Vehicle:

yes

Remarks:

reconstituted water

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
Before test start, the highest concentration with a loading rate of 100 mg test item/L was prepared by mixing 100.7 mg test item into 1007 mL test water by ultrasonication for 15 minutes and then stirring for 24 hours at room temperature in the dark to dissolve as much test item as possible. Then, non-dissolved fractions of the test item were separated from the test medium by membrane filtration (0.45 μm cellulose acetate filter). The filtrate was used as the test medium of the highest test concentration. Adequate volumes of this filtrate were diluted with test water to prepare the test media of the desired dilutions of 1:2, 1:4, 1:8 and 1:16.

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: Green algae
- Strain: Pseudokirchneriella subcapitata
- Source (laboratory, culture collection): „Sammlung von Algenkulturen, Albrecht-von-Haller-Institut für Pflanzenwissenschaften, Universität Göttingen", 37073 Göttingen, Germany.
- Method of cultivation: The algae were cultivated in the laboratories of ibacon under standardised conditions according to the test guidelines.

ACCLIMATION
- Acclimation period: 4 days
- Culturing media and conditions (same as test or not): same as test

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Hardness:

0.24 mmol/L as CaCO3

Test temperature:

21.2 to 21.9 °C

pH:

8.0 at test start and
8.2 to 9.2 at test end

Salinity:

NA

Nominal and measured concentrations:

nominal concentrations: 100, 50, 25, 12.5 and 6.25 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: Erlenmeyer flasks
- Type: flasks were covered with glass dishes
- Material, size, fill volume: glass, 50 mL, 50 mL
- Initial cells density: 5000 algal cells per mL test medium
- Control end cells density: approx. 63E+4 cells/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per vehicle control (replicates): 3

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: according to OECD Guideline
- Culture medium different from test medium: no

OTHER TEST CONDITIONS
- Sterile test conditions: no
- Adjustment of pH: no
- Photoperiod: Continuous illumination
- Light intensity and quality: 4540 to 5300 lux

EFFECT PARAMETERS MEASURED:
- Determination of cell concentrations: spectrophotometer

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2
- Range finding study
- Results used to determine the conditions for the definitive study: Based on the range finding study the following concentrations were chosen for the main study: 6.25, 12.5, 25, 50, 100 mg/L.

Reference substance (positive control):

no

Remarks:

For the evaluation of the quality of the algae and the experimental conditions the reference item potassium dichromate is tested at least twice a year to demonstrate satisfactory test conditions.

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95% conf. interval > 100 mg/L

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

54.3 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95% conf. interval: 50.2 - 58.6 mg/L

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

25 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

63.1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: Yield

Remarks on result:

other: 95% conf. interval: 60.1 - 66.2

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

33 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: Yield

Remarks on result:

other: 95% conf. interval: 29.9 - 36.3 mg/L

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

25 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: Yield

Details on results:

- Exponential growth in the control (for algal test): yes
- Observation of abnormalities (for algal test): no
- Unusual cell shape: The algae cells of the nominal concentrations of 50 and 100 mg test item/L were smaller and thicker compared to the control.
- Colour differences: No remarkable observations, clear test medium.

Results with reference substance (positive control):

- Results with reference substance valid? Yes
- EC50: 1.12 mg/L (growth rate) after 72 hours exposure
- Other: 72-h EC10 = 0.541 mg/L (growth rate)

Reported statistics and error estimates:

Based on the calculated cell densities, the 72 hours ErC50 and the 72 hours EyC50, the corresponding EC20 and EC10 values and where possible their 95 %-confidence limits were calculated by Probit analysis.
For the determination of the 72 hours LOEC and the 72 hours NOEC, the calculated growth rates and yields at each test concentration were tested for significant differences compared to the control values by Williams t-test (yield) and Bonferroni-Welch t-test (growth rate).
The software used to perform the statistical analysis was ToxRat Professional, Version 3.2.1, ToxRat Solutions GmbH.

Analytical determination

The results of the ICP-OES method including the method validation data show that this method was not suitable for the analysis of the test medium samples. In contrast to the ICP-OES method it was possible to determine specific aluminium concentrations in the samples using the more sensitive GF-AAS method. The aluminium concentrations found were between 0.05 and 0.09 mg/L for the "Filtrate" samples and between 0.07 and 0.16 mg/L for the control samples. Therefore, no significant quantities of the active ingredient aluminium of the test item were found in the aqueous test samples of the test medium which were prepared at the test facility during the algae study.

Validity criteria fulfilled:

yes

Conclusions:

The 72-hour EC50 value for growth rate was calculated to be > 100 mg/L. The 72-hour NOEC for growth rate was determined to be 25 mg/L.

Executive summary:

The purpose of this test was to determine the inhibitory effect of the test item on the growth of the freshwater green algae Pseudokirchneriella subcapitata in a static concentration-response test.

For this purpose, exponentially growing cultures of this unicellular green algal species were exposed to various concentrations (6.25, 12.5, 25, 50, and 100 mg/L) of the test item under defined conditions. The highest test concentration was a filtrate with a loading rate of 100 mg test item/L. No higher concentrations could be tested due to the limit of solubility of the test item in the test water. Due to limited analytical techniques to quantify the test item in the test media the calculations are conducted with nominal values.

The inhibition of growth in relation to control cultures was determined over a test period of 72 hours, and thus over several algal generations.

At test start 50 mL of the test concentrations were inoculated with approx. 5000 algal cells per mL test medium and defined volumes of the algal suspensions were sampled after 24, 48 and 72 hours for determination of cell densities by spectrophotometrical measurement.

The following values were determined after an exposure period of 72 hours.

EC50 (growth rate) > 100 mg/L

EC10 (growth rate) = 54.3 mg/L

NOEC (growth rate) = 25 mg/L.

Description of key information

The 72 -hour EC50 value for growth rate was calculated to be > 100 mg/L and the 72 -h EC10 value for growth rate was determined to be 54.3 mg/L.

Key value for chemical safety assessment

EC10 or NOEC for freshwater algae:

54.3 mg/L

Additional information

The purpose of this test was to determine the inhibitory effect of the test item on the growth of the freshwater green algae Pseudokirchneriella subcapitata in a static concentration-response test.

For this purpose, exponentially growing cultures of this unicellular green algal species were exposed to various concentrations (6.25, 12.5, 25, 50, and 100 mg/L) of the test item under defined conditions. The highest test concentration was a filtrate with a loading rate of 100 mg test item/L. No higher concentrations could be tested due to the limit of solubility of the test item in the test water. Due to limited analytical techniques to quantify the test item in the test media the calculations are conducted with nominal values.

The inhibition of growth in relation to control cultures was determined over a test period of 72 hours, and thus over several algal generations.

At test start 50 mL of the test concentrations were inoculated with approx. 5000 algal cells per mL test medium and defined volumes of the algal suspensions were sampled after 24, 48 and 72 hours for determination of cell densities by spectrophotometrical measurement.

The following values were determined after an exposure period of 72 hours.

EC50 (growth rate) > 100 mg/L

EC10 (growth rate) = 54.3 mg/L

NOEC (growth rate) = 25 mg/L.