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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Reference
Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
November 8, 2012 - February 19, 2013
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Version / remarks:
adopted March 23, 2006
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.3 (Algal Inhibition test)
Version / remarks:
Council Regulation (EC) No. 761/2009 laying down test methods pursuant to Regulation (EC) No. 1907/2006 of the European Parliament and the council on the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH).
Deviations:
no
GLP compliance:
yes (incl. certificate)
Analytical monitoring:
no
Details on sampling:
The test material concentration in the reconstituted water was not quantified at the start and the end of this study due to the low water solubility (< 0.051 mg/L). Because of the low water solubility, the compound cannot be detected with standard analytical methods. The development of an analytical method with a sufficiently low detection and quantification limit is complex. Due to the absence of any adverse effects at the saturation concentration, the study was performed without analytical concentration verification.
Vehicle:
yes
Details on test solutions:
The test medium (reconstituted water and test item) was prepared freshly. Therefore, the calibrated flask with test medium was treated in an ultrasonic device for 1 hour. Subsequently, the preparation was stirred with a magnetic stirrer for further 23 hours. Afterwards, the formulation was passed through a nutsch filter with a pore size of 10-20 µm. The filtrate was used for the study.

Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
TEST ORGANISM
- Common name: Green algae
- Strain: Desmodesmus subspicatus
- Source (laboratory, culture collection): laboratory
- Age of inoculum (at test initiation): freshly prepared
- Method of cultivation: standard

ACCLIMATION
- Acclimation period: 3 days
- Culturing media and conditions (same as test or not): same
- Any deformed or abnormal cells observed: none
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
72 h
Post exposure observation period:
-
Hardness:
250 mg/L
Test temperature:
23 °C
pH:
7.95 - 8.91
Nominal and measured concentrations:
nominal: 100.0 mg/L

Details on test conditions:
TEST SYSTEM
- Test vessel: 6 replicates
- Type (delete if not applicable): open
- Initial cells density: 10000 cells/mL
- No. of vessels per concentration (replicates): 6
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes
- Detailed composition if non-standard medium was used:
mg/L
NH4Cl 15.00000
MgCl2 * 6 H2O 12.00000
CaCl2 * 2 H2O 18.00000
MgSO4 * 7 H2O 15.00000
KH2PO4 1.60000

FeCl3 * 6 H2O 0.06400
Na2EDTA * 2 H2O 0.10000

H3BO3 0.18500
MnCl2 * 4 H2O 0.41500
ZnCl2 0.00300
CoCl2 * 6 H2O 0.00150
CuCl2 * 2 H2O 0.00001
Na2MoO4 * 2 H2O 0.00700

NaHCO3 50.00000

The pH of the reconstituted water after aeration is approximately 8.
Reference substance (positive control):
yes
Remarks:
potassium dichromate
Key result
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: > 0.051 mg/L
Key result
Duration:
72 h
Dose descriptor:
EC20
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: > 0.051 mg/L
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: > 0.051 mg/L
Key result
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: Yield
Remarks on result:
other: > 0.051 mg/L
Key result
Duration:
72 h
Dose descriptor:
EC20
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: Yield
Remarks on result:
other: > 0.051 mg/L
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: Yield
Remarks on result:
other: > 0.051 mg/L
Results with reference substance (positive control):
The sensitivity of the test system has to be demonstrated periodically using potassium dichromate.
Under the given experimental conditions, the test material Art. 104864 (potassium dichromate) showed 72 h EC values which are within the recommended range (Yield EC50 0.20 – 0.75 mg/L and Growth rate EC50 of 0.60 –1.03 mg/L).
Validity criteria fulfilled:
yes
Conclusions:
An aqueous preparation of 100 mg/L (nominal) of the test item revealed no toxic effect in the test system. The 72-hours EC50 and EC10 could not be determined, because it exceeded the maximum solubility of the test material in reconstituted water (EC50 > 0.051 mg/L).
Executive summary:

The objective of this study was to determine the influence of the test item on the growth and growth rate of the unicellular green algal species Desmodesmus subspicatus. The study design included one control group and one test material group with six replicates, each containing 100 mL reconstituted water or test medium and about 10000 cells/mL at the start of the experimental phase.
The study was performed as a limit test in an open static test system. The algae were exposed to s filtrate of nominal 100 mg test material per L. The growth of the algae was calculated after 24, 48, and 72 hours exposure in the test item and control groups.

This study was performed according to GLP and the methods applied are fully compliant with OECD TG 201.

The test material concentration in the reconstituted water was not quantified at the start and the end of this study due to the low water solubility (< 0.051 mg/L). Because of the low water solubility, the compound cannot be detected with standard analytical methods. The development of an analytical method with a sufficiently low detection and quantification limit is complex. Due  to  the  absence of  any  adverse  effects  at  the  saturation  concentration,  the  study  was performed without analytical concentration verification.

EC values:

For the test item, the following values for Desmodesmus subspicatus were determined:

Parameter (0-72 h) Growth rate Yield
EC10 > 100 mg/L (nominal) > 100 mg/L (nominal)
EC20 > 100 mg/L (nominal) > 100 mg/L (nominal)
EC50 > 100 mg/L (nominal) > 100 mg/L (nominal)
NOEC > 100 mg/L (nominal) > 100 mg/L (nominal)
LOEC > 100 mg/L (nominal) > 100 mg/L (nominal)

An aqueous preparation of 100 mg/L (nominal) of the test item revealed no toxic effect in the test system. The 72 hours EC50 and EC10 could not be determined, because it exceeded the maximum solubility of the test material in reconstituted water (EC50 > 0.051 mg/L).

Description of key information

No adverse effects on algae were observed up to the limit of water solubility. Thus, the 72 -h EC50 value and 72 -h EC10 value are greater than 0.051 mg/L which corresponds to a nominal concentration of 100 mg/L.

Key value for chemical safety assessment

Additional information