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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:
(Q)SAR
Adequacy of study:
key study
Study period:
2016-10-13 to 2016-10-14
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
Reason / purpose:
reference to same study
Reason / purpose:
reference to other study
Reference:
Composition 0
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)
Deviations:
yes
Remarks:
Calculation method
Qualifier:
equivalent or similar to
Guideline:
EU Method C.3 (Algal Inhibition test)
Deviations:
yes
Remarks:
Calculation method
Principles of method if other than guideline:
The growth inhibition of algae was determined using validated QSAR model for the Mode of Action in question (esters). The QSAR model is based on validated data for a training set of 44 chemicals derived from 72-hour ErC50 test on algae, for which the concentrations of the test item had been determined by chemical analyses over the test period.
GLP compliance:
no
Test material information:
Composition 1
Analytical monitoring:
no
Details on sampling:
Not applicable
Vehicle:
no
Details on test solutions:
Not applicable
Test organisms (species):
other: Results from the following species were used in the regression: Pseudokirchneriella subcapitata, Desmodesmus subspicatus, Scenedesmus quadricauda
Details on test organisms:
Following the principles of Phase Equilibrium Thermodynamics, for narcotic substances, no difference in relationship between solubility and ecotoxicity between algae (or indeed other) aquatic species is expected. Any observed differences may be attributed to lifestyle related parameters and relative duration of study versus bodysize rather than to a specific toxic mechanism causing species differences. In this case, for esters, no differences were observed in activity based toxicity for the 3 species used.
Test type:
other: QSAR
Water media type:
not specified
Limit test:
no
Total exposure duration:
72 h
Remarks on exposure duration:
72h-ErC50
Post exposure observation period:
Not applicable
Hardness:
No data
Test temperature:
The temperatures varied from approximately 20 to 25 °C depending on the species used to construct the algorithm. This small difference is not expected to contribute to the variability of the ErC50 values found in experimental data.
pH:
Test results were preferably taken from studies with measured pHs between 6 - 9. However it is recognized that in some cases (due to high luminosity) the pH may increase in the control and lower concentrations (which do not cause significant effect over the study period). This pH increase did not generally disqualify the study from being used in the test and validation set for non-polar chemicals.
Dissolved oxygen:
No data
Salinity:
No data
Conductivity:
No data
Nominal and measured concentrations:
No data
Details on test conditions:
Results from a test duration of 72 hours only were used for this algorithm. Following OECD 201, all studies were from a static test design. For suspected volatile substances only tests performed in closed vessels were accepted unless accompanying analytical monitoring proved such a design was not necessary.
Reference substance (positive control):
not required
Key result
Duration:
72 h
Dose descriptor:
other: ErC50
Effect conc.:
4.9 mg/L
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other:
Remarks:
95% CL: 4.2 - 5.6 mg/L
Details on results:
The water solubility value given as input to the Ecotox modules of the iSafeRat® HAQSAR models falls within the descriptor domain of the model between log water solubility (in log (mol/L)) of -5.57 to 0.93. Moreover the test substance is attributed to the class of esters.
Results with reference substance (positive control):
Not applicable
Reported statistics and error estimates:
Not applicable

None

Validity criteria fulfilled:
yes
Conclusions:
Based on a QSAR model used to calculate the inhibition of growth to algae of test item NERYL ACETATE, the estimated 72 h-ErC50 is 4.9 mg/L.
Executive summary:

A QSAR model was used to calculate the inhibition of growth to algae of test item NERYL ACETATE. This QSAR model has been validated to be compliant with the OECD recommendations for QSAR modeling (OECD, 2004) and predicts the endpoint value which would be expected when testing the substance under experimental conditions in a laboratory following Guideline for Testing of Chemicals No. 201, "Freshwater Alga and Cyanobacteria, Growth Inhibition Test" (1), referenced as Method C.3 of Commission Regulation No. 440/2008 (2). The criterion predicted was the ErC50 (Median Effective Concentration for specific growth rate), a statistically derived concentration which is expected to cause 50% inhibition of intrinsic rate of growth of the test system within a period of 72 hours.

The growth inhibition of algae was determined using validated QSAR model for the Mode of Action in question (esters). The QSAR model is based on validated data for a training set of 44 chemicals derived from 72-hour ErC50 test on algae, for which the concentrations of the test item had been determined by chemical analyses over the test period.

The result below is the toxicity values anticipated further to a 72-hour study on algae based on measured concentrations: the predicted 72-hour ErC50 is 4.9 mg/L.

Description of key information

Based on a QSAR model used to calculate the inhibition of growth to algae of test item NERYL ACETATE, the estimated 72 h-ErC50 for is 4.9 mg/L.

Key value for chemical safety assessment

EC50/LC50 for freshwater algae:
4.9 mg/L

Additional information

A QSAR model was used to calculate the inhibition of growth to algae of test item NERYL ACETATE. This QSAR model has been validated to be compliant with the OECD recommendations for QSAR modeling (OECD, 2004) and predicts the endpoint value which would be expected when testing the substance under experimental conditions in a laboratory following Guideline for Testing of Chemicals No. 201, "Freshwater Alga and Cyanobacteria, Growth Inhibition Test" (1), referenced as Method C.3 of Commission Regulation No. 440/2008 (2). The criterion predicted was the ErC50 (Median Effective Concentration for specific growth rate), a statistically derived concentration which is expected to cause 50% inhibition of intrinsic rate of growth of the test system within a period of 72 hours.

The growth inhibition of algae was determined using validated QSAR model for the Mode of Action in question (esters). The QSAR model is based on validated data for a training set of 44 chemicals derived from 72-hour ErC50 test on algae, for which the concentrations of the test item had been determined by chemical analyses over the test period.

The result below is the toxicity values anticipated further to a 72-hour study on algae based on measured concentrations: the predicted 72-hour ErC50 is 4.9 mg/L.