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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
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Specific details on test material used for the study:
- Name of test material (as cited in study report): C-SAT 090069
- Physical state: amber viscous liquid
- Analytical purity: > 89%
- Lot/batch No.: C-081
- Expiration date of the lot/batch:26.03.2013
- Storage condition of test material: room temperature
Analytical monitoring:
yes
Details on sampling:
- Concentrations: 300 mL test solutions from the concentration levels 2.5, 5, 10, 20 and 40 mg/L culture medium and pure culture medium were filled each into conical flasks and stored under the same conditions as the test vessels. After 0, 24, 48 and 72 h, 30 mL of each sample were transferred to a 50 mL glass flask, which were closed with screw cap and were immediately shipped to the test site.
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: Test concentrations were prepared by adding corresponding amounts of test substance to 1 L test medium and stirring at 300 rpm for 24 h. Afterwards the test substance preparations were filtered through a filter paper circle (Ø 320 mm).
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
TEST ORGANISM
- Strain: 86.81
- Source (laboratory, culture collection): Sammlung von Algenkulturen, Göttingen, University of Göttingen, Germany
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Test temperature:
25.0 - 25.2 °C
pH:
7.81 - 9.60
Nominal and measured concentrations:
Nominal: 2.5, 5, 10, 20 and 40 mg/L
Measured: Analytical results show that the test substance could not be quantified reproducibly by LCMS analysis. The class of compounds the test substance belongs to is prone to hydrolysis in aqueous solution and forms the corresponding aldehyde, not covered by the specific method of analysis applied. The corresponding aldehyde has a comparable hydrophobicity as the test substance. Therefore it is expected that also the aquatic toxicity of both is comparable. As a result, the toxicity should be attributed to the nominal concentration.
Details on test conditions:
TEST SYSTEM
- Test vessel: 300 mL vessels with 150 mL test solution
- Initial cells density: 5E3 cells/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: according to guideline
- Culture medium different from test medium: yes
- Intervals of water quality measurement: The pH was measured at the beginning and at the end of the test.

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Photoperiod: continuous light
- Light intensity and quality: 8000 lux

EFFECT PARAMETERS MEASURED: The cell concentration in each vessel was determined after 0, 24, 48 and 72 h by photometry (578 nm, cuvette width = 50 mm).
- Determination of cell concentrations: spectrophotometer
Reference substance (positive control):
no
Key result
Duration:
72 h
Dose descriptor:
EL50
Effect conc.:
36.3 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
(WAF)
Basis for effect:
growth rate
Key result
Duration:
72 h
Dose descriptor:
EL10
Effect conc.:
14.9 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
(WAF)
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EL50
Effect conc.:
18.2 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
(WAF)
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
EL10
Effect conc.:
13.7 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
(WAF)
Basis for effect:
biomass
Validity criteria fulfilled:
yes
Conclusions:
In a study according to OECD test guideline 201 under GLP, the growth rate/yield EC50 of the test substance was determined to be 36.3/18.2 mg/L with a EC10 of 13.7/14.9 mg/L (nominal concentrations).
Executive summary:

The test substance was tested in the Alga, Growth Inhibition Test according to the OECD Guideline for the Testing of Chemicals No. 201 (23 March 2006) using the single cell green algae desmodesmus subspicatus as test organism under GLP. The experiment was carried out as a static test, i.e. the test substance preparations were not exchanged for the whole exposure period of 72 hours. Based on non-GLP pre-test results the test substance was identified as poorly soluble in culture medium. The test was performed with test substance preparations of nominal 2.5; 5; 10; 20; 40 mg/L culture medium. After 24 h of stirring the test substance preparations were filtered. All test concentrations were present as clear solutions.

During this study the test substance concentrations of nominal 2.5; 5; 10; 20; 40 mg/L culture medium and the control (culture medium) were determined by LC-MS. Analytical results show that the test substance could not be quantified reproducibly by LC-MS analysis. The class of compounds the test substance belongs to is prone to hydrolysis in aqueous solution and forms the corresponding aldehyde, not covered by the specific method of analysis applied. The corresponding aldehyde has a comparable hydrophobicity as the test substance. Therefore it is expected that also the aquatic toxicity of both is comparable. As a result, the toxicity should be attributed to the nominal concentration.

The test concentrations and the controls were inoculated with 5000 cells/mL. Validation experiments and the pre-cultivation ensured that the algae were of appropriate viability and sensitivity. After 0, 24, 48 and 72h exposure period the extinction of an aliquot of the cultures was measured photometrically for determination of algae growth. Yield and growth rate were calculated.

Growth rate/yield EC50 of the test substance is determined to be 36.3/18.2 mg/L with corresponding EC10 of 13.7/14.9 mg/L (nominal concentrations).

Description of key information

EL50 (72h) = 36.3 mg/L, EL10 (72h) = 14.9 mg/L (nominal, WAF) for growth rate of Desmodesmus subspicatus (OECD 201)

Key value for chemical safety assessment

EC50 for freshwater algae:
36.3 mg/L
EC10 or NOEC for freshwater algae:
14.9 mg/L

Additional information

One study investigating the toxicity of the test substance to freshwater algae is available. The test was performed according to GLP and OECD guideline 201 using the single cell green algae Desmodesmus subspicatus as test organism (Wehrhahn 2010). The experiment was carried out as a static test. After 24 h of stirring the test substance preparations were filtered. All test concentrations were present as clear solutions. During this study the test substance concentrations of nominal 2.5, 5, 10, 20 and 40 mg/L culture medium and the control (culture medium) were determined by LC-MS. Analytical results show that the test substance could not be quantified reproducibly by LC-MS analysis. The class of compounds the test substance belongs to is prone to hydrolysis in aqueous solution and forms the corresponding aldehyde, not covered by the specific method of analysis applied. The corresponding aldehyde has a comparable hydrophobicity as the test substance. Therefore, it is expected that also the aquatic toxicity of both is comparable. As a result, the toxicity should be attributed to the nominal concentration.

The test concentrations and the controls were inoculated with 5000 cells/mL. Validation experiments and the pre-cultivation ensured that the algae were of appropriate viability and sensitivity. After 0, 24, 48 and 72h exposure period the extinction of an aliquot of the cultures was measured photometrically for determination of algae growth. The 72h-EL50 (growth rate) is determined to be 36.3 mg/L and the corresponding EL10 is determined to be of 14.9 mg/L based on the nominal concentrations.

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