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Toxicity to aquatic algae and cyanobacteria

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Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
(Q)SAR
Adequacy of study:
key study
Study period:
2020-02-12
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification
Justification for type of information:
Please refer to attached QMRF and QPRF Documents
Qualifier:
according to
Guideline:
other: REACH guidance on QSARS R.6
Principles of method if other than guideline:
Calculation of toxicity in Algae. Software used: ECOSAR 1.11 (EPISUITE) for chemical class "Vinyl/Allyl Ethers"
GLP compliance:
no
Specific details on test material used for the study:
SMILES : O(CCO)CC=C
Analytical monitoring:
not required
Test organisms (species):
other: Algae
Water media type:
freshwater
Remarks on exposure duration:
acute and chronic exposure (duration not specified)
Key result
Duration:
96 h
Dose descriptor:
EC50
Effect conc.:
796.73 mg/L
Remarks on result:
other: QSAR predicted value: The substance is within the applicability domain of the model

Values used to Generate ECOSAR Profile:

Log Kow: -0.061    (EPISuite Kowwin v1.68 Estimate)

Wat Sol: 4.54E+005 (mg/L, EPISuite WSKowwin v1.43 Estimate)

Conclusions:
Using ECOSAR v1.11 the toxicity 96-h EC50 value for Algae was determined to be 796.73 mg/L. The substance is within the applicability domain of the model.
Executive summary:

Using ECOSAR v1.11 the toxicity 96-h EC50 value for Algae was determined to be 796.73 mg/L. The substance is within the applicability domain of the model.

The adequacy of a prediction depends on the following conditions:

a) the (Q)SAR model is scientifically valid: the scientific validity is established according to the OECD principles for (Q)SAR validation;

b) the (Q)SAR model is applicable to the query chemical: a (Q)SAR is applicable if the query chemical falls within the defined applicability domain of the model;

c) the (Q)SAR result is reliable: a valid (Q)SAR that is applied to a chemical falling within its applicability domain provides a reliable result;

d) the (Q)SAR model is relevant for the regulatory purpose.

For assessment and justification of these 4 requirements the QMRF and QPRF files were developed and attached to this study record.

Description of the prediction Model

The prediction model was descripted using the harmonised template for summarising and reporting key information on (Q)SAR models. For more details please refer to the attached QSAR Model Reporting Format (QMRF) file.

Assessment of estimation domain

The assessment of the estimation domain was documented in the QSAR Prediction Reporting Format file (QPRF). Please refer to the attached document for the details of the prediction and the assessment of the estimation domain.

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)
Qualifier:
according to
Guideline:
EU Method C.3 (Algal Inhibition test)
Qualifier:
according to
Guideline:
EPA OPPTS 850.5400 (Algal Toxicity, Tiers I and II)
GLP compliance:
yes (incl. certificate)
Analytical monitoring:
yes
Details on sampling:
Three parallel samples were taken from each test concentration and from the control on both days of the analytical occasion.
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
The test solutions used in the test were prepared by mechanical dispersion without the aid of any solubilising agents. The test solutions were freshly prepared at the beginning of the experiment. A stock solution of 100 mg/L (nominal concentration) was prepared in OECD medium. The further test solutions were prepared by appropriate dilution of this stock solution.
- Controls:
Untreated Control: OECD Medium (without test item) was inoculated and examined in parallel in the study.
Toxic Reference Control: For the evaluation of the quality of the algae and the experimental conditions, potassium dichromate is tested at least twice a year to demonstrate satisfactory test conditions.
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
TEST ORGANISM
- Common name: green algae
- Source (laboratory, culture collection): supplied by the SAG: Collection of Algal Cultures, Inst. Plant Physiology, University of Göttingen, Untere Karspüle 2, D-37073 Göttingen, Germany
- Breeding conditions: The pre-culture is intended to give an amount of algae suitable for the inoculation of test cultures. The pre-culture was prepared with OECD Medium, incubated under the conditions of the test and used when still exponentially growing, normally after an incubation period of about three days.
Test type:
static
Water media type:
freshwater
Remarks:
OECD Medium, according to OECD 201
Limit test:
yes
Total exposure duration:
72 h
Post exposure observation period:
no
Test temperature:
22 - 23 °C
pH:
7 - 9
Nominal and measured concentrations:
nominal and measured concentrations
Details on test conditions:
TEST SYSTEM
- Test vessel: Erlenmeyer flasks of ~250 mL volume, Volumes of 100 mL algal suspension per replicate were continuously shaken by a laboratory orbital shaker in flasks for an exposure time of 72 hours
- Type: closed, flasks were covered with air-permeable stoppers
- Initial cells density: The test was started (0 hours) by inoculation of 0.1 mL algal biomass (1E07 algal cells per mL) to 100 mL test item solution. The initial cell density was about 1E04 cells/ mL in each test flask.
- 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: Reconstituted algal growth medium (OECD Medium, according to OECD 201) was used as dilution water in the experiment. Separate stock solutions were first prepared in deionised water. The growth medium was prepared by adding an appropriate volume of these different stock solutions to deionised water in order to achieve the final concentrations. Stock solution 1 (macro nutrients): NH4Cl 15.0 mg/L, MgCl2 (anhydrous) 5.6 mg/L, CaCl2 × 2 H2O 18.0 mg/L, MgSO4 × 7 H2O 15.0 mg/L, KH2PO4 1.6 mg/L
Stock solution 2 (iron): FeCl3 × 6 H2O 64.0 μg/L, Na2EDTA × 2H2O 100.0 μg/L
Stock solution 3 (trace elements): H3BO3 185.0 μg/L, MnCl2 × 4 H2O 415.0 μg/L, ZnCl2 3.0 μg/L,
CoCl2 × 6 H2O 1.5 μg/L, CuCl2 × 2 H2O 0.01 μg/L, Na2MoO4 × 2 H2O 7.0 μg/L
Stock solution 4 (bicarbonate): NaHCO3 50.0 mg/L
- Culture medium different from test medium: no

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: The algal culture flasks were continuously illuminated.
- Light intensity and quality: The average light intensity measured at the position occupied by algal culture flasks during the test was 7998 lux, 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:
- Determination of cell concentrations: The cell numbers were determined at 24, 48 and 72 hours after starting the test by manual cell counting using a microscope with counting chamber.
- Other: The morphological changes of algal cells compared to the control were examined at 24, 48 and 72 hours after starting the test using a microscope.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2.5
- Range finding study
In order to select appropriate test concentrations for use in the definitive test, a preliminary range-finding test was conducted to determine the approximate toxicity of the test item. A stock solution of 100 mg/L (nominal concentration) was prepared by dissolving the test item in OECD medium. The further test solutions were prepared by appropriate dilution of this stock solution. Untreated control ran parallel in the test. Algal cells were exposed to each concentration of the test item plus control, for 72 hours. The test was performed with two replicates in treatment groups and three replicates in the control.
Reference substance (positive control):
yes
Remarks:
Potassium dichromate (K2Cr2O7)
Key result
Duration:
72 h
Dose descriptor:
EC50
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: results not yet available
Key result
Duration:
72 h
Dose descriptor:
EC10
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: results not yet available
Conclusions:
The algal growth inhibition will be determined.
Executive summary:

A study will be performed in accordance with OECD TG 201 in order to determine the algal growth inhibition. The study was initiated in January 2020 but was not completed by the CRO in due time to complete the registration dossier. The study record will be updated as soon as the results will become available.

Description of key information

Using ECOSAR v1.11 the toxicity 96-h EC50 value for Algae was determined to be 616.5 mg/L. The substance is within the applicability domain of the model.

Key value for chemical safety assessment

EC50 for freshwater algae:
616.5 mg/L

Additional information

Using ECOSAR v1.11 the toxicity to aquatic algae 96-h EC50 value was determined to be 616.5 mg/L. This value exceeds the estimated water solubility of 445 mg/L, but no effects up to the water solubility are expected. The substance is within the applicability domain of the model.

A study will be performed in accordance with OECD TG 201 in order to determine the algal growth inhibition. The study was initiated in January 2020 but was not completed by the CRO in due time to complete the registration dossier. The study record will be updated as soon as the results will become available.