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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:
November 2012
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:
1. SOFTWARE : ISIDA Predictor (version October 2020)

2. MODEL: ISIDA Consensus – Algae short-term toxicity (EC50) regression model

3. SMILES USED AS INPUT FOR THE MODEL : FC(F)(Cl)Cl

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL : “ISIDA Consensus – Daphnia short-term toxicity (EC50) regression model” is a consensus model based on 15 individual models (IM) built using Support Vector Machine (SVM) as machine learning method. Each IM has its own ISIDA descriptor space (DS) and method hyperparameters, which were optimized by genetic algorithm search.

5. APPLICABILITY DOMAIN :
The model is applicable to heterogeneous organic chemicals. The applicability domain is assessed using the "fragment control" approach, which is closely related to the chemical structure of the test substance and the employed descriptor space (i.e. the type of fragmentation pattern).
The structure was in the domain of 4 models out of 15 models

6. ADEQUACY OF THE RESULT
Based on the number of individual models applicable for the prediction, the result is considered of average reliability.
Guideline:
other: REACH Guidance on QSARs R.6
Principles of method if other than guideline:
- Software tool(s) used including version: ISIDA Predictor (version October 2020)
- Model(s) used: ISIDA Consensus – Algae short-term toxicity (EC50) regression model
- Model description: see field 'Attached justification'
- Justification of QSAR prediction: see field 'Attached justification'
GLP compliance:
no
Specific details on test material used for the study:
SMILES notation: FC(F)(Cl)Cl
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
ca. 67.216 mg/L
Nominal / measured:
estimated
Basis for effect:
growth rate
Remarks on result:
other: QSAR predicted value
Validity criteria fulfilled:
yes
Remarks:
compound was within the applicability domain
Conclusions:
The prediction of the growth inhibition model is EC50 at 72 hrs: 67.216 mg/l (sd: 0.42 mg/L).
On the basis of this, it is proposed that the substance could potentially be hazardous to Algae

The risk phrase: H412: Harmful to aquatic life with long lasting effects is applicable.
Executive summary:

Algae EC50, 72 hrs: 67.216 mg/l. On the basis of this, it is proposed that the substance could potentially be hazardous to Algae

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
(Q)SAR
Adequacy of study:
key study
Study period:
January 2021
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:
QSAR prediction: Validated QSAR calculation method.

1. SOFTWARE: ECOSAR V2.0

2. MODEL: organic module, class Neutral organics (algae equations, 2012)
Log EC50 (mmol/L) = -0.6922 (log Kow) + 0.9253, r2=0.6782

3. SMILES USED AS INPUT FOR THE MODEL: FC(F)(Cl)Cl

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL : See attached QMRF and/or QPRF

5. APPLICABILITY DOMAIN: see attached documents
- Descriptor domain: Maximum LogKow: 6.4, maximum MW: 1000

6. ADEQUACY OF THE RESULT
The assessed molecule falls in the applicability domains. The results can be used for hazard assessment.

Guideline:
other: REACH Guidance on QSARs R.6
Principles of method if other than guideline:
- Software tool(s) used including version: ECOSAR
- Model(s) used: ECOSAR v2.00 for estimation of aquatic toxicity of chemicals
- Model description: see field 'Attached justification'
- Justification of QSAR prediction: see field 'Attached justification' '

GLP compliance:
no
Specific details on test material used for the study:
SMILES notation: FC(F)(Cl)Cl
Key result
Duration:
96 h
Dose descriptor:
EC50
Effect conc.:
56.4 mg/L
Nominal / measured:
estimated
Conc. based on:
test mat.
Basis for effect:
not specified
Remarks on result:
other: QSAR predicted value
Remarks:
Prediction using software-estimated LogKow
Key result
Duration:
96 h
Dose descriptor:
EC50
Effect conc.:
32.56 mg/L
Nominal / measured:
estimated
Conc. based on:
test mat.
Basis for effect:
not specified
Remarks on result:
other: QSAR predicted value
Remarks:
Prediction using the experimental LogKow
Details on results:
Associated water solubility: 280 mg/L
Validity criteria fulfilled:
yes
Remarks:
the molecule is within the applicability domain
Conclusions:
Assessment of the short-term toxicity to green algae was conducted using ECOSAR v2.0.
The 96-hr EC50 was determined to be 56.4 mg/l using the estimated LogKow of 1.82 (as calulated by KOWWIN).
The 96-hr EC50 was determined to be 32.56 mg/l using the measured LogKow of 2.16
According to these results the substance could be harmful to green algae.

Executive summary:

The results of this give a 96-hr LC50 of 32.56 mg/l or 56.1 mg/l. 

These QSAR predictions indicate that the substance could potentially be hazardous to Algae.

 

Description of key information

Algal toxicity from validated QSARs prediction:

ECOSAR model v2.0: EC50 (96h) = 56.4 mg/l (with estimated LogKow) or 32.56 mg/l (with experimental LogKow)

ISIDA Predictor model: EC50 (72h) = 67.2 mg/l

QSAR Toolbox : ErC50 (72h) : 71.3 mg/l

Key value for chemical safety assessment

EC50 for freshwater algae:
32.56 mg/L

Additional information

In the absence of experimental data and considering this regulated substance has no direct emissions to the aquatic compartments, assessments of Algal toxicity were conducted using validated QSARs developed for short-term toxicity prediction in green algae.

QSAR determinations were consistent and support an EC50 between 10 and 100 mg/L, indicating the substance is potentially harmful to green algae.

The lowest predicted value of 32.56 mg/l is retained for input in the chemical safety assessment.