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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:
2017-03-08
Reliability:
1 (reliable without restriction)
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:
1. SOFTWAREiSafeRat® toolbox – in Silico Algorithms For Environmental Risk And Toxicity version 2.22. MODEL (incl. version number)iSafeRat® holistic HA-QSAR v1.63. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODELC1C(CCC)COC(=O)C14. SCIENTIFIC VALIDITY OF THE (Q)SAR MODELSee attached QMRF5. APPLICABILITY DOMAINSee attached QPRF6. ADEQUACY OF THE RESULTSee attached QPRF
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
no
Remarks:
QSAR model
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
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL- Source and lot/batch No.of test material: not applicable- Expiration date of the lot/batch: not applicable- Purity test date: not applicable STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL- Storage condition of test material: not applicable- Stability under test conditions: not applicable- Solubility and stability of the test substance in the solvent/vehicle: not applicable- Reactivity of the test substance with the solvent/vehicle of the cell culture medium: not applicable
Analytical monitoring:
no
Details on sampling:
not applicable
Vehicle:
no
Details on test solutions:
not applicable
Test organisms (species):
other: algae
Details on test organisms:
not applicable
Test type:
other: QSAR model
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Remarks on exposure duration:
not applicable
Post exposure observation period:
not applicable
Hardness:
The QSAR model is based on data from studies performed at acceptable hardness to ensure control survival.
Test temperature:
The QSAR model is based on data from studies performed at between 20 - 25 °C (depending on the species considered).
pH:
The QSAR model is based on data from studies performed at pH between 6.0 - 9.0. 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:
The QSAR model is based on data from studies performed on freshwater species.
Conductivity:
No data
Nominal and measured concentrations:
The QSAR is based on data studies performed using measured concentrations or with acceptable stability.
Details on test conditions:
not applicable
Reference substance (positive control):
no
Remarks:
QSAR model
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
367 mg/L
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 95CI: [292-460] mg/L
Details on results:
- Descriptor domain: The water solubility value given as input to the Ecotox module of the iSafeRat® Holistic HA-QSAR falls within the descriptor domain of the model between log water solubility (in log (mol/L)) of -5.57 to 0.93.- Structural fragment domain: All chemical group within the molecular structure is taken into account by the model.- Mecanistic domain, if relevant: Currently, the ecotoxicity module of the iSafeRat® Holistic HA-QSAR can reliably predict the acute aquatic toxicity for mono- and poly-esters based on the chemical structure. The test item as a lactone (cyclic ester) is expected to fall on the esters regression line.- Considerations on structural analogues: iSafeRat® Holistic HA-QSAR is mainly based on the thermodynamic relationship between water solubility and the aquatic toxicity. This model was constructed using high quality data for water solubility and algal growth inhibition test for 44 esters compounds.
Results with reference substance (positive control):
not applicable
Reported statistics and error estimates:
95% confidence interval (α = 0.05): 292 – 460 mg/LQSAR statistical parameters are given in the QMRF and QPRF.

no data

Validity criteria fulfilled:
yes
Conclusions:
The test item falls within the applicability domain of the model and was therefore reliably predicted for its acute toxicity (72h-ErC50) to algae. Therefore, this endpoint value can be considered valid for use in risk assessment and classification and labelling.
Executive summary:

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

The toxicity to algae of the test item has been investigated using a QSAR model that predicts inhibition of algal growth rate immobility in an OECD 201 study.

The test item falls falls within the applicability domain of the model.

The predicted value of the toxicity to algae (72h-ErC50) based on growth rate inhibition was predicted as equal to 367 mg test item/L.

This toxicity study is acceptable and can be used for that endpoint.

Results synopsis

Test type: QSAR model

ErC50: 367 mg test item/L.

95% Confidence Interval: [292 - 460] mg test item/L

Description of key information

The toxicity to algae of the test item has been determined using a validated QSAR model for the Mode of Action in question (esters).

The 72h-ErC50 based growth rate inhibition was predicted as 367 mg test item/L. 95% Confidence Interval: 292 - 460 mg test item/L

Key value for chemical safety assessment

EC50 for freshwater algae:
367 mg/L

Additional information

The QSAR used is based on validated data for a training set of 44 esters derived from 72-hour test on algae, for which the concentrations of the test item had been determined by chemical analyses over the test period. The model provides 72h-ErC50 predictions for fish from High Accuracy QSAR models which are based on ecotoxicologically validated studies and statistically validated regressions for a series of Modes of Action described within the QMRF. As such the results from these studies are considered accurate enough to replace an experimental study when the test substance falls within the appropriate applicability domain.

The test item falls within the applicability domain of the model and can therefore be considered a reliably prediction for acute toxicity (72h-ErC50) to algae. Therefore, this endpoint value can be considered valid for use in risk assessment and classification and labelling.