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Toxicity to aquatic algae and cyanobacteria

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Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From 23 February 1995 to 10 March 1995
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Remarks:
This study was carried out according to international OECD Guideline No. 201 with GLP statement. Minor deviation was observed (the pH of the control increase by more than 1.5 units during the test) but was considered to have no effect on the results of the test. Furthermore, cell density values were not specified in this report, all performance criteria cannot be verified.
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
yes
Remarks:
. The pH of the control increase by more than 1.5 units during the test. This minor deviation was considered to have no effect on the results of the test.
Principles of method if other than guideline:
Not applicable
GLP compliance:
yes (incl. certificate)
Remarks:
1994-01-31
Specific details on test material used for the study:
- Storage condition of test material: metal bottle at room temperature
Analytical monitoring:
yes
Details on sampling:
- Concentrations: solvent control and each test group: 14 mg/L, at 0 and 96 hours
- Sampling method: An aliquot (250 mL) of each test sample was extracted with three portions (3 x 50 mL) of dichloromethane, each extract being filtered through anhydrous sodium sulphate. The combined extracts were evaporated to dryness and the residue dissolved in ethyl acetate (10 mL) to give a final theoretical test material concentration of 350 mg/L.
- Sample storage conditions before analysis: no data
Vehicle:
yes
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: For the purpose of the definitive study the test material was prepared using a preliminary solution in 10% v/v Tween 80-dimethylformamide. An amount of test material (3.50 g) was dissolved in solvent and the volume adjusted to 25 mL to give a 3.50 g/25 mL solvent stock solution. An aliquot (200 µL) of this solvent stock solution was dispersed in 2 litres of algal suspension to give the test concentration of 14 mg/L.
- Eluate: solvent
- Differential loading: 3.50 g of test material/25 mL solvent
- Controls: 2 controls (control + solvent control)
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): dimethylformamide
- Concentration of vehicle in test medium (stock solution and final test solution(s) including control(s)): 10% v/v Tween 80 - dimethylformamide
- Evidence of undissolved material (e.g. precipitate, surface film, etc): no data
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
TEST ORGANISM
- Common name: Selenastrum capricornutum (Printz)
- Strain: CCAP 278/4
- Source (laboratory, culture collection): From the Culture Centre for Algae and Protozoa (CCAP), Institute of Freshwater Ecology, Ferry House, Ambleside, Cumbria.
- Age of inoculum (at test initiation): no data
- Method of cultivation: Cultures were maintained in the laboratory by the transfer of algal cells to fresh culture medium approximately once per week. The culture was maintained in the laboratory at a temperature of 24 +/- 1°C under continuous illumination (intensity approximately 7000 lux) and constant aeration.

ACCLIMATION
none
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
96 h
Remarks on exposure duration:
none
Post exposure observation period:
None
Hardness:
No data
Test temperature:
Temperature was maintained at 24°C throughout the study.
pH:
The pH values of the control and test cultures were observed to increase from pH 8.0 - 8.1 at 0 hours to pH 10.1 - 10.3 at 96 hours.
This effect is considered to be due to the large number of cells in the log phase of growth respiring oxygen and producing carbonates and bicarbonates as part of photosynthesis/respiration which in solution give rise to alkaline conditions.
Dissolved oxygen:
No data
Salinity:
Not applicable
Nominal and measured concentrations:
Nominal concentration: 14 mg/L.
Measured concentration: Analysis of the test solutions at 0 hours showed the measured test concentrations to be near nominal (97%, corresponding to 13.6 mg/L). However, analysis of the test solutions at 96 hours showed a marked decline in the mean measured test concentrations to 8-9 of nominal (corresponding to 1.06-1.21 mg/L).
Details on test conditions:
TEST SYSTEM
- Test vessel: stoppered glass conical flasks
- Type (delete if not applicable): stoppered
- Material, size, headspace, fill volume: 250 mL
- Aeration: yes
- Type of flow-through (e.g. peristaltic or proportional diluter): not applicable
- Renewal rate of test solution (frequency/flow rate): not applicable
- Initial cells density: 10^4 cells/mL
- Control end cells density: 3.07x10^6 cells/mL
- No. of organisms per vessel: not applicable (initial cells density of 10^4 cells/mL)
- No. of vessels per concentration (replicates): 6
- No. of vessels per control (replicates): 3
- No. of vessels per vehicle control (replicates): 3

GROWTH MEDIUM
- Standard medium used: yes
- Detailed composition if non-standard medium was used: not applicable

TEST MEDIUM / WATER PARAMETERS
No data

OTHER TEST CONDITIONS
- Sterile test conditions: no
- Adjustment of pH: no
- Photoperiod: continuous illumination
- Light intensity and quality: intensity approximately 7000 Lux
- Salinity (for marine algae): not applicable

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: Samples were taken at O, 24, 48, 72 and 96 hours and the absorbance measured at 665 nm using a Jenway 6100 Spectrophotometer. The cell densities of the control cultures at 0, 24, 48. 72 and 96 hours. were determined by direct counting with the aid of a haemocytometer to confirm that the absorbance values were sufficiently well correlated with cell density values to be used to monitor the growth of the test cultures.
- Chlorophyll measurement: no
- Other: none

TEST CONCENTRATIONS
- Spacing factor for test concentrations: not applicable (limit test)
- Justification for using less concentrations than requested by guideline: not applicable
- Range finding study: yes. The test concentration to be used in the definitive study was determined by a preliminary range-finding study. The range-finding study was conducted by exposing Selenastrum capricornutum cells to a nominal test concentration of 14 mg/L for a period of 96 hours.
- Test concentrations: 14 mg/L
- Results used to determine the conditions for the definitive study: Based on the result of the range-finding study a "limit test" was conducted for the definitive study at a test concentration of 14 mg/L to confirm that at the highest attainable test concentration of 14 mg/L, no effect on algal growth was observed.
Reference substance (positive control):
no
Key result
Duration:
96 h
Dose descriptor:
EC50
Effect conc.:
> 1.1 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks:
and biomass
Key result
Duration:
96 h
Dose descriptor:
NOEC
Effect conc.:
>= 1.1 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks:
and biomass
Details on results:
- Exponential growth in the control (for algal test): yes
- Observation of abnormalities (for algal test): All test and control cultures were inspected microscopically at 96 hours. There were no abnormalities detected in any of the control or test cultures at 14 mg/L.

- Growth data:
The following data:
Mean cell density of control at 0 h: 2.47x104 cells/ml ;
Mean cell density of control at 72 h: 7.09x105 cell s/ml ;
Mean cell density of control at 96 h: 3.07x106 cells/ml ;
Mean cell density of solvent control at 0 h: 2.47x104 cells/ml ;
Mean cell density of solvent control at 72 h: 7.23x105 cells/ml ;
Mean cell density of solvent control at 96 h: 3. Ox106 cell s/ml ;
show that the cell concentration of the solvent control cultures increased by a factor of 29 during the test in line with the OECD Guideline that states the enhancement must be at least by a factor of 16 after 72 hours.
Results with reference substance (positive control):
Not applicable
Reported statistics and error estimates:
Statistical analysis of the area under the growth curve data was carried out for the solvent control and 14 mg/l test group using Students t-test. There were no statistically significant differences (P >= 0.05), between the control and 14 mg/L test group and therefore the "No Observed Effect Concentrati on" (NOEC) is given as greater than or equal to 14 mg/L .

Table 6.1.5/1: Absorbance and pH values in the definitive study

Nominal concentration (mg/L)

pH

Absorbance values

pH

0h

0h

24h

48h

72h

96h

96h

Control

R1

R2

R3

Mean value

8.0

8.0

8.0

 

0.032

0.033

0.032

0.032

0.089

0.087

0.097

0.091

0.349

0.357

0.314

0.340

0.872

0.856

0.851

0.860

1.799

1.832

1.724

1.785

10.2

10.3

10.1

 

Solvent control

R1

R2

R3

Mean value

8.0

8.0

8.0

 

0.032

0.031

0.031

0.031

0.101

0.079

0.092

0.091

0.309

0.314

0.356

0.326

0.841

0.872

0.824

0.846

1.709

1.692

1.672

1.691

10.1

10.2

10.3

14

R1

R2

R3

R4

R5

R6

Mean value

8.1

8.0

8.0

8.0

8.1

8.0

0.032

0.032

0.032

0.033

0.032

0.032

0.032

0.101

0.095

0.092

0.085

0.098

0.100

0.095

0.342

0.333

0.349

0.362

0.341

0.317

0.341

0.865

0.819

0.884

0.814

0.859

0.862

0.851

1.628

1.714

1.702

1.784

1.793

1.729

1.725

10.2

10.2

10.1

10.3

10.3

10.2

R1 - R6 = Replicates 1 and 6

Table 6.1.5/2: Inhibition of growth

Nominal concentration (mg/L)

Area under curve at 72h

% Inhibition

Area under curve at 96h

% Inhibition

Growth rate (24-48h)

% Inhibition

Control

18.744

-

49.680

-

0.055

-

Solvent control

18.300

-

47.964

-

0.053

-

14

18.576

[2]

48.870

[2]

0.053

0

[increase in growth as compared to solvent control]

Validity criteria fulfilled:
not specified
Remarks:
Cell density values were not specified in this report. All performance criteria cannot be verified. However, the biomass in the control cultures increased exponentially by a factor of at least 16 within the test period.
Conclusions:
The EC50 value, based on measured test concentrations were greater than 1.1 mg/L and correspondingly the NOEC was greater than or equal to 1.1 mg/L.
Executive summary:

This study was performed to assess the effect of the test material, space on the growth of Selenastrum capricornutum. The method followed that described in the OECD Guideline No. 201.

Following a preliminary range-finding study, Selenastrum capricornutum was exposed to an aqueous dispersion of the test material at a concentration of 14 mg/L (six replicate flasks) for 96 hours, under constant illumination and shaking at a temperature of 24°C. Samples of the algal populations were removed daily and absorbance values determined for each control and treatment group.

Exposure of Selenastrum capricornutum to the test material gave EC50 value of greater than 14 mg/L and correspondingly the NOEC was greater than or equal to 14 mg/L. The test concentration of 14 mg/L was the highest attainable test concentration that could be prepared due to the limited solubility of the test material in water and auxiliary solvent and having due regard to the amount of auxiliary solvent permitted in the test under the OECD Guidelines. Analysis of the test solutions throughout the study showed a marked decline in test concentrations and so it was considered justifiable to base the results on the measured test concentrations also. The EC50 value, based on measured test concentrations were greater than 1.1 mg/L and correspondingly the NOEC was greater than or equal to 1.1 mg/L.

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
(Q)SAR
Remarks:
QSAR result on the C6 isomers of the transformation product of the registered substance
Adequacy of study:
supporting study
Study period:
Run on 2016-01
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 limited documentation / justification
Remarks:
(Q)SAR method with established scientific validity. The substance, the C6 isomers of the transformation product of the registered substance, falls within the applicability domain of the model.
Justification for type of information:
1. SOFTWARE
EPISUITE v4.1

2. MODEL (incl. version number)
ECOSAR v1.11

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
C6 isomers of the transformation product of the registered substance: C1C(C)(C)CCCC1C(C)OC(C)(C)COH
log Pow: 4.33 (experimental result)

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
Neutral Organics SAR document in "Attached background material".

5. APPLICABILITY DOMAIN
See attached QPRFs for acute and chronic endpoints

6. ADEQUACY OF THE RESULT
See attached QPRFs for acute and chronic endpoints
Qualifier:
according to
Guideline:
other: REACH guidance on QSARs R.6, May 2008
Deviations:
no
Principles of method if other than guideline:
See attached QPRF for the acute and chronic endpoints
GLP compliance:
no
Remarks:
(not relevant)
Specific details on test material used for the study:
- log Pow: 4.33 (experimental result)
Details on sampling:
Not applicable
Details on test solutions:
Not applicable
Test organisms (species):
other: Green algae
Details on test organisms:
Not applicable
Test type:
not specified
Water media type:
not specified
Total exposure duration:
96 h
Remarks on exposure duration:
none
Post exposure observation period:
Not applicable
Hardness:
Not applicable
Test temperature:
Not applicable
pH:
Not applicable
Dissolved oxygen:
Not applicable
Salinity:
Not applicable
Nominal and measured concentrations:
Not applicable
Details on test conditions:
Not applicable
Key result
Duration:
96 h
Dose descriptor:
EC50
Effect conc.:
1.94 mg/L
Remarks on result:
other: ECOSAR Class: Neutral Organics
Key result
Dose descriptor:
other: ChV
Effect conc.:
0.82 mg/L
Remarks on result:
other: ECOSAR Class: Neutral Organics
Details on results:
Validity of model for acute endpoint (96hr EC50):
1. Defined Endpoint: Toxicity to aquatic algae (96hr EC50).
2. Unambigous algorithm: Linear regression QSAR; Log 96h-EC50 (mmol/L) = -0.6922*log Kow + 0.9253. To convert the EC50 from mmol/L to mg/L, multiply by the molecular weight.
3. Applicability domain: applicable to chemicals with log Kow less than 6.4 and molecular weight less than 1000 g/mol. The model can be suitable for chemicals class of neutral organic.
4. Statistical characteristics: N = 41+9 and the coefficient of determination R² = 0.6782.
5. Mechanistic interpretation: related to the partitioning of the substance from water into the organisms lipid phase.

Validity of model for chronic endpoint (ChV):
1. Defined Endpoint: Toxicity to aquatic algae (chronic value ChV).
2. Unambigous algorithm: Linear regression QSAR; Log ChV (mmol/L) = -0.6029*log Kow + 0.1648. To convert the ChV from mmol/L to mg/L, multiply by the molecular weight.
3. Applicability domain: applicable to chemicals with log Kow less than 8.0 and molecular weight less than 1000 g/mol. The model can be suitable for chemicals class of neutral organic.
4. Statistical characteristics: N = 34+5 and the coefficient of determination R² = 0.6971.
5. Mechanistic interpretation: related to the partitioning of the substance from water into the organisms lipid phase.

Adequacy of predictions: the substance falls within the applicability domains described above and therefore the predicted values can be considered reliable. For more information, see Neutral Organics SAR document in "Attached background material".
Results with reference substance (positive control):
Not applicable
Reported statistics and error estimates:
Acute endpoint: N = 41+9 and the coefficient of determination R² = 0.6782.
Chronic endpoint: N = 34+5 and the coefficient of determination R² = 0.6971.

No additional information

Validity criteria fulfilled:
yes
Conclusions:
THe C6 isomers of the transformation product of the registered substance were predicted to have an 96h-EC50 of 1.94 mg/L and a ChV of 0.82 mg/L to green algae. The substance falls within the applicability domains and therefore the predicted values can be considered reliable.
Executive summary:

Toxicity to green algae of the C6 isomers of the transformation product of the registered substance was estimated using the ECOSAR v1.11 QSAR model available from the U.S. EPA. The estimated 96h-EC50 and ChV values were 1.94 mg/L and 0.82 mg/L (neutral organics class), respectively, calculated from a measured log Kow value (4.33) and linear regressions:

Log 96h-EC50 (mmol/L) = -0.6922*log Kow + 0.9253

Log ChV (mmol/L) = -0.6029*log Kow + 0.1648

The substance falls within the applicability domains and therefore the predicted values can be considered reliable.

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
(Q)SAR
Remarks:
QSAR result on the C6 isomers of the transformation product of the registered substance
Adequacy of study:
supporting study
Study period:
From 2016-01-05 to 2016-01-06
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
Remarks:
QSAR value. The substance, the C6 isomers of the transformation product of the registered substance, falls into the applicability domain of the model QSAR.
Justification for type of information:
1. SOFTWARE
iSafeRat® HA-QSAR based on a holistic approach for predicting physicochemical and ecotoxicological endpoints: Short-term toxicity to algae (inhibition of the exponential growth rate)
iSafeRat® High Accuracy QSAR to predict the toxicity (72h NOEC) in the algal growth inhibition test: Short-term toxicity to algae (inhibition of the exponential growth rate)

2. MODEL (incl. version number)
iSafeRat® holistic HA-QSAR v1.5
iSafeRat® - NOEC algae 72h v1.1

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
C6 isomers of the transformation product of the registered substance: C1C(C)(C)CCCC1C(C)OC(C)(C)COH
Water solubility = 35.0 mg/L (KREATIS internal study, 2015), derived using the log Kow experimental value at 4.33

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
See attached QMRFs for acute and chronic endpoints

5. APPLICABILITY DOMAIN
See attached QPRFs for acute and chronic endpoints

6. ADEQUACY OF THE RESULT
See attached QPRFs for acute and chronic endpoints
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
not applicable
Remarks:
(QSAR model)
Qualifier:
equivalent or similar to
Guideline:
EU Method C.3 (Algal Inhibition test)
Deviations:
not applicable
Remarks:
(QSAR model)
Principles of method if other than guideline:
The purpose of this QSAR is to accurately predict the toxicity to algae as would be expected in a laboratory experiment following OECD Guideline 201 and EC method C.3 for specific, named modes of action (e.g. nonpolar narcotics) to provide a value that can effectively replace a 72-hour NOECr and a 72-hour ErC50 value from an experimental study. The regression based method used to achieve this has been fully validated following the OECD (2004) recommendations (refer to the QMRF with JRC/KREATIS QMRF identifier: Q19-46-51-448 for further details).
GLP compliance:
no
Specific details on test material used for the study:
- Mode of action: non-polar narcotic (MOA 1 or MechoA 1.1)
- Log Kow = 4.33 (from experimental study)
- Water solubility = 35.0 mg/L (KREATIS internal study, 2015)
Analytical monitoring:
no
Details on sampling:
Not applicable
Vehicle:
no
Details on test solutions:
Not applicable
Test organisms (species):
other: Pseudokirchneriella subcapitata, Desmodesmus subspicatus, Scenedesmus quadricauda
Details on test organisms:
Results from the following species were used in the regression: Pseudokirchneriella subcapitata, Desmodesmus subspicatus, Scenedesmus quadricauda.
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 (e.g. shell closing in molluscs) and relative duration of study versus bodysize rather than to a specific toxic mechanism causing species differences. In this case, for MOA 1 or MechoA 1.1, no differences were observed in activity based toxicity for the 3 species used.
Test type:
other: QSAR method
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Remarks on exposure duration:
none
Post exposure observation period:
Not applicable
Hardness:
The QSAR is based on data from studies performed at acceptable hardness to ensure control survival.
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:
The QSAR is based on data from studies performed at acceptable pH between 6.0 - 9.0.
Dissolved oxygen:
The QSAR is based on data from studies performed at acceptable oxygen concentrations (generally >60%).
Salinity:
Not applicable.
Nominal and measured concentrations:
The QSAR is based on data from 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.:
2.4 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 95% CL: 2.0-2.8 mg/L
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
0.84 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 95% CL: 0.67-1.1 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 -4.38 to 0.49. Moreover the test substance is attributed to the class of non-polar narcotic compounds.
Results with reference substance (positive control):
Not applicable
Reported statistics and error estimates:
QSAR statistical parameters are given in the QMRF and the QPRFs

No additional information

Validity criteria fulfilled:
yes
Remarks:
The substance falls into applicability domains of the QSAR model
Conclusions:
The 72-h ErC50 and 72-h NOECr values of the C6 isomers of the transformation product of the registered substance, based on measured concentrations, were determined to be 2.4 mg/L (95%-CL: 2.0-2.8 mg/L) and 0.84 mg/L (95% CL: 0.67-1.1 mg/L), respectively.
Executive summary:

A QSAR model was used to calculate the inhibition of growth to algae of the test item. This QSAR model has been validated to be compliant with the OECD recommendations for QSAR modelling (OECD, 2004) and predicts the endpoint value which would be expected when testing the substance under experimental conditions in a laboratory following OECD Guideline 201 and EU Method C.3. The first criterion predicted was the NOECr (No Observed Effect Concentration for specific growth rate), a tested concentration which is expected to cause no effect on intrinsic rate of growth of the test system within a period of 72 hours. The other predicted criterion 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 a validated QSAR for the Mode of Action in question, (MOA 1 or MechoA 1.1, non-polar narcosis). The QSAR models are based on validated data for a training set of 40 chemicals derived from 72-hour ErC50 and 31 chemicals derived from 72-hour NOECr test on algae, for which the concentrations of the test item had been determined by chemical analyses over the test period. The water solubility of the substance given as input was predicted by the iSafeRat® solubility module using the experimental log Kow value of the substance, measured at 4.33. The substance falls within the applicability domain of the models as demonstrated in the QPRFs.

The 72-h ErC50 and 72-h NOECr values of the C6 isomers of the transformation product of the registered substance, based on measured concentrations, were determined to be 2.4 mg/L (95%-CL: 2.0-2.8 mg/L) and 0.84 mg/L (95% CL: 0.67-1.1 mg/L), respectively.

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
(Q)SAR
Remarks:
QSAR result on the C7 isomer of the transformation product of the registered substance
Adequacy of study:
supporting study
Study period:
Run on 2016-03
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 limited documentation / justification
Remarks:
(Q)SAR method with established scientific validity. The substance, the C7 isomer of the transformation product of the registered substance, falls within the applicability domain of the model.
Justification for type of information:
1. SOFTWARE
EPISUITE v4.1

2. MODEL (incl. version number)
ECOSAR v1.11

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
C7 isomer of the transformation product of the registered substance: OCC(C)(C)OC1CC(C)(C)CCCC1C
log Pow: 4.40 (KREATIS QSAR - iSafeRat v1.5, 2016)

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
Neutral Organics SAR document in "Attached background material".

5. APPLICABILITY DOMAIN
See attached QPRFs for acute and chronic endpoints

6. ADEQUACY OF THE RESULT
See attached QPRFs for acute and chronic endpoints
Qualifier:
according to
Guideline:
other: REACH guidance on QSARs R.6, May 2008
Deviations:
no
Principles of method if other than guideline:
See attached QPRF for the acute and chronic endpoints
GLP compliance:
no
Remarks:
(not relevant)
Specific details on test material used for the study:
- log Pow: 4.40 (KREATIS QSAR - iSafeRat v1.5, 2016)
Details on sampling:
Not applicable
Details on test solutions:
Not applicable
Test organisms (species):
other: Green algae
Details on test organisms:
Not applicable
Test type:
not specified
Water media type:
not specified
Total exposure duration:
96 h
Remarks on exposure duration:
none
Post exposure observation period:
Not applicable
Hardness:
Not applicable
Test temperature:
Not applicable
pH:
Not applicable
Dissolved oxygen:
Not applicable
Salinity:
Not applicable
Nominal and measured concentrations:
Not applicable
Details on test conditions:
Not applicable
Key result
Duration:
96 h
Dose descriptor:
EC50
Effect conc.:
1.73 mg/L
Remarks on result:
other: ECOSAR Class: Neutral Organics
Key result
Dose descriptor:
other: ChV
Effect conc.:
0.74 mg/L
Remarks on result:
other: ECOSAR Class: Neutral Organics
Details on results:
Validity of model for acute endpoint (96hr EC50):
1. Defined Endpoint: Toxicity to aquatic algae (96hr EC50).
2. Unambigous algorithm: Linear regression QSAR; Log 96h-EC50 (mmol/L) = -0.6922*log Kow + 0.9253. To convert the EC50 from mmol/L to mg/L, multiply by the molecular weight.
3. Applicability domain: applicable to chemicals with log Kow less than 6.4 and molecular weight less than 1000 g/mol. The model can be suitable for chemicals class of neutral organic.
4. Statistical characteristics: N = 41+9 and the coefficient of determination R² = 0.6782.
5. Mechanistic interpretation: related to the partitioning of the substance from water into the organisms lipid phase.

Validity of model for chronic endpoint (ChV):
1. Defined Endpoint: Toxicity to aquatic algae (chronic value ChV).
2. Unambigous algorithm: Linear regression QSAR; Log ChV (mmol/L) = -0.6029*log Kow + 0.1648. To convert the ChV from mmol/L to mg/L, multiply by the molecular weight.
3. Applicability domain: applicable to chemicals with log Kow less than 8.0 and molecular weight less than 1000 g/mol. The model can be suitable for chemicals class of neutral organic.
4. Statistical characteristics: N = 34+5 and the coefficient of determination R² = 0.6971.
5. Mechanistic interpretation: related to the partitioning of the substance from water into the organisms lipid phase.

Adequacy of predictions: the substance falls within the applicability domains described above and therefore the predicted values can be considered reliable. For more information, see Neutral Organics SAR document in "Attached background material".
Results with reference substance (positive control):
Not applicable
Reported statistics and error estimates:
Acute endpoint: N = 41+9 and the coefficient of determination R² = 0.6782.
Chronic endpoint: N = 34+5 and the coefficient of determination R² = 0.6971.

No additional information

Validity criteria fulfilled:
yes
Conclusions:
The C7 isomer of the transformation product of the registered substance was predicted to have an 96h-EC50 of 1.73 mg/L and a ChV of 0.74 mg/L to green algae. The substance falls within the applicability domains and therefore the predicted values can be considered reliable.
Executive summary:

Toxicity to green algae of the C7 isomer of the transformation product of the registered substance was estimated using the ECOSAR v1.11 QSAR model available from the U.S. EPA. The estimated 96h-EC50 and ChV values were 1.73 mg/L and 0.74 mg/L (neutral organics class), respectively, calculated from an estimated log Kow (4.40) and linear regressions:

Log 96h-EC50 (mmol/L) = -0.6922*log Kow + 0.9253

Log ChV (mmol/L) = -0.6029*log Kow + 0.1648

The substance falls within the applicability domains and therefore the predicted values can be considered reliable.

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
(Q)SAR
Remarks:
QSAR result on the C7 isomer of the transformation product of the registered substance
Adequacy of study:
supporting study
Study period:
From 2016-03-14 to 2016-03-16
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
Remarks:
QSAR value. The substance, the C7 isomer of the transformation product of the registered substance, falls into the applicability domain of the model QSAR.
Justification for type of information:
1. SOFTWARE
iSafeRat® HA-QSAR based on a holistic approach for predicting physicochemical and ecotoxicological endpoints: Short-term toxicity to algae (inhibition of the exponential growth rate)
iSafeRat® High Accuracy QSAR to predict the toxicity (72h NOEC) in the algal growth inhibition test: Short-term toxicity to algae (inhibition of the exponential growth rate)

2. MODEL (incl. version number)
iSafeRat® holistic HA-QSAR v1.5
iSafeRat® - NOEC algae 72h v1.1

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
C7 isomer of the transformation product of the registered substance: OCC(C)(C)OC1CC(C)(C)CCCC1C
Water solubility = 29.1 mg/L (KREATiS – Internal Study (2016))

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
See attached QMRFs for acute and chronic endpoints

5. APPLICABILITY DOMAIN
See attached QPRFs for acute and chronic endpoints

6. ADEQUACY OF THE RESULT
See attached QPRFs for acute and chronic endpoints
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
not applicable
Remarks:
(QSAR model)
Qualifier:
equivalent or similar to
Guideline:
EU Method C.3 (Algal Inhibition test)
Deviations:
not applicable
Remarks:
(QSAR model)
Principles of method if other than guideline:
The purpose of this QSAR is to accurately predict the toxicity to algae as would be expected in a laboratory experiment following OECD Guideline 201 and EC method C.3 for specific, named modes of action (e.g. nonpolar narcotics) to provide a value that can effectively replace a 72-hour NOECr and a 72-hour ErC50 value from an experimental study. The regression based method used to achieve this has been fully validated following the OECD (2004) recommendations (refer to the QMRF with JRC/KREATIS QMRF identifier: Q19-46-51-448 for further details).
GLP compliance:
no
Specific details on test material used for the study:
- Mode of action: non-polar narcotic (MOA 1 or MechoA 1.1)
- log Kow : 4.40 (KREATIS, 2016)
- Water solubility = 29.1 mg/L (KREATIS internal study, 2016)
Analytical monitoring:
no
Details on sampling:
Not applicable
Vehicle:
no
Details on test solutions:
Not applicable
Test organisms (species):
other: Pseudokirchneriella subcapitata, Desmodesmus subspicatus, Scenedesmus quadricauda
Details on test organisms:
Results from the following species were used in the regression: Pseudokirchneriella subcapitata, Desmodesmus subspicatus, Scenedesmus quadricauda.
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 (e.g. shell closing in molluscs) and relative duration of study versus bodysize rather than to a specific toxic mechanism causing species differences. In this case, for MOA 1 or MechoA 1.1, no differences were observed in activity based toxicity for the 3 species used.
Test type:
other: QSAR method
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Remarks on exposure duration:
none
Post exposure observation period:
Not applicable
Hardness:
The QSAR is based on data from studies performed at acceptable hardness to ensure control survival.
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:
The QSAR is based on data from studies performed at acceptable pH between 6.0 - 9.0.
Dissolved oxygen:
The QSAR is based on data from studies performed at acceptable oxygen concentrations (generally >60%).
Salinity:
Not applicable.
Nominal and measured concentrations:
The QSAR is based on data from 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.:
2 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 95% CL: 1.7-2.4 mg/L
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
0.73 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 95% CL: 0.57-0.92 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 -4.38 to 0.49. Moreover the test substance is attributed to the class of non-polar narcotic compounds.
Results with reference substance (positive control):
Not applicable
Reported statistics and error estimates:
QSAR statistical parameters are given in the QMRF and the QPRFs

No additional information

Validity criteria fulfilled:
yes
Remarks:
The substance falls into applicability domains of the QSAR model
Conclusions:
The 72-h ErC50 and 72-h NOECr values of the C7 isomer of the transformation product of the registered substance, based on measured concentrations, were determined to be 2.0 mg/L (95%-CL: 1.7-2.4 mg/L) and 0.73 mg/L (95% CL: 0.57-0.92 mg/L), respectively.
Executive summary:

A QSAR model was used to calculate the inhibition of growth to algae of the test item. This QSAR model has been validated to be compliant with the OECD recommendations for QSAR modelling (OECD, 2004) and predicts the endpoint value which would be expected when testing the substance under experimental conditions in a laboratory following OECD Guideline 201 and EU Method C.3. The first criterion predicted was the NOECr (No Observed Effect Concentration for specific growth rate), a tested concentration which is expected to cause no effect on intrinsic rate of growth of the test system within a period of 72 hours. The other predicted criterion 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 a validated QSAR for the Mode of Action in question, (MOA 1 or MechoA 1.1, non-polar narcosis). The QSAR models are based on validated data for a training set of 40 chemicals derived from 72-hour ErC50 and 31 chemicals derived from 72-hour NOECr test on algae, for which the concentrations of the test item had been determined by chemical analyses over the test period. The water solubility of the substance given as input was predicted by the iSafeRat® solubility module. The substance falls within the applicability domain of the models as demonstrated in the QPRFs.

The 72-h ErC50 and 72-h NOECr values of the C7 isomer of the transformation product of the registered substance, based on measured concentrations, were determined to be 2.0 mg/L (95%-CL: 1.7-2.4 mg/L) and 0.73 mg/L (95% CL: 0.57-0.92 mg/L), respectively.

Description of key information

OECD Guideline 201, GLP, key study, validity 2:

96h-EC50 (Selenastrum capricornutum) > 1.1 mg/L; 96h-NOEC (Selenastrum capricornutum) >= 1.1 mg/L, based on measured concentrations.

Key value for chemical safety assessment

Additional information

One valid key study, according to the OECD Guideline 201 performed according to GLP, is available to assess the toxicity of the registered substance on the growth of Selenastrum capricornutum. Following a preliminary range-finding study, Selenastrum capricornutum was exposed to an aqueous dispersion of the test substance at a concentration of 14 mg/L (six replicate flasks) for 96 hours. Samples of the algal populations were removed daily and absorbance values determined for each control and treatment group. Analysis of the test solutions throughout the study showed a marked decline in test concentrations and so it was considered justifiable to base the results on the measured test concentrations. The 96h-EC50 value, based on growth rate and biomass was greater than 1.1 mg/L (the highest attainable test substance concentration based on the geometric mean of measured concentration over the study period) and the NOEC was greater than or equal to 1.1 mg/L.

In addition, the toxicity of the transformation product (C6 and C7 isomers) of the registered substance to green algae was estimated using two QSAR models. The two QSAR models were ECOSAR v1.11 and iSafeRat. Both QSAR results were considered reliable as the substances, the C6 and C7 isomers of the transformation product of the registered substance, fall within the applicability domain of the models. The estimated 72 -96h-EC50 values for the C6 isomers were 1.94 mg/L and 2.4 mg/L, using ECOSAR v1.11 and iSafeRat holistic approach v1.5, respectively. The estimated chronic values for the C6 isomers were 0.82 mg/L (ChV) and 0.84 mg/L (72h-NOECr), using ECOSAR v1.11 and iSafeRat High Accuracy QSAR v1.1, respectively. In addition, the estimated 72-96h-EC50 values for the C7 isomer were 1.73 mg/L and 2.0 mg/L, using ECOSAR v1.11 and iSafeRat holistic approach v1.5, respectively. The estimated chronic values for the C7 isomer were 0.74 mg/L (ChV) and 0.73 mg/L (72h-NOECr), using ECOSAR v1.11 and iSafeRat High Accuracy QSAR v1.1, respectively.

The worst case endpoint values, estimated at 1.73 mg/L for acute endpoint and 0.73 mg/L for chronic endpoint, are chosen as key data for the toxicity of the transformation product to aquatic algae.

These data demonstrate that the transformation product of the registered substance is not Toxic (non-T) in the context of PBT assessment.