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Toxicity to aquatic algae and cyanobacteria

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Endpoint:
toxicity to aquatic algae and cyanobacteria
Remarks:
ErC50 at 72h
Type of information:
(Q)SAR
Adequacy of study:
key study
Study period:
2017
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:
The executive summary of the QSAR prediction is presented in the endpoint summary. The QMRF and QPRF documentation files are included in the Attached justification section.
Reference:
Composition 0
Qualifier:
according to
Guideline:
other: REACH Guidance R.6: QSARs and grouping of chemicals. Version May 2008.
Version / remarks:
In the QMR attached the model specifications are presented. In this QMR is referenced to the Methodology document for the Ecological Structure-Activity Relationship model (ECOSAR) Class Program MS Windows v1.11'. United States Environmental Protection Agency, Office of Pollution Prevention and Toxics, Washington DC (2012).
Deviations:
not applicable
GLP compliance:
no
Remarks:
not required
Test material information:
Composition 1
Test organisms (species):
other: green algae
Water media type:
freshwater
Total exposure duration:
72 h
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
5.3 mg/L
Nominal / measured:
estimated
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: log Kow 2.82; ECOSAR class: Esters
Validity criteria fulfilled:
yes
Remarks:
The ECOSAR-Ester equation is valid when using the OECD criteria. In addition, N=20 and R2 is 0.86
Conclusions:
The 72h-ErC50 of the substance to green algae is 5.3 mg/L.
Executive summary:

The acute algae ErC50 for the ester Herbacet #1 is predicted to be 5.3 mg/L based on the ECOSAR SAR for esters using an estimated log Kow of 2.82, molecular weight of 166.2 and the equation: Log 96-h EC50 (mmol/L) = -0.6993 (log Kow) + 0.4715. The 96h-EC50 is considered equivalent to the 72h ErC50 as defined in OECD TG 201.

 

Herbacet #1 is in the applicability domain of the ECOSAR prediction because: a) Herbacet #1 is an ester; b) its log Kow is 2.82 (=< 6.4); c) its MW is 166.2 (< 1000); and; d) the toxicity predicted is below its measured water solubility of 739 mg/L.

The measured and predicted log Kow’s of Herbacet #1 are very similar (2.8 and 2.82, respectively). The closest analogue in the training set is Octyl lactate, with a log Kow of 2.8 and a molecular weight of 202. The predicted EC50 value of this ECOSAR analogue is 7.0 mg/L and the measured value is 7.6 mg/L, presenting the limited uncertainty of the prediction for Octyl lactate and therefore for Herbacet #1.

The fit in the applicability domain and the availability of an analogue in the training set results in limited uncertainty of the Herbacet #1 prediction. This shows that the prediction is reliable and a Klimisch 2 can be assigned. In accordance with REACH Annex XI, the validity of the (Q)SAR is documented in a QMR for acute algae toxicity on esters. The adequate and reliable documentation, presented in the Attached justification section, further supports this prediction.

Endpoint:
toxicity to aquatic algae and cyanobacteria
Remarks:
ErC10/NOEC
Type of information:
(Q)SAR
Adequacy of study:
key study
Study period:
2017
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:
The executive summary of the QSAR prediction is presented in the endpoint summary. The QMRF and QPRF documentation files are included in the Attached justification section.
Reference:
Composition 0
Qualifier:
according to
Guideline:
other: REACH Guidance R.6: QSARs and grouping of chemicals. Version May 2008.
Version / remarks:
In the QMR attached the model specifications are presented. In this QMR is referenced to the Methodology document for the Ecological Structure-Activity Relationship model (ECOSAR) Class Program MS Windows v1.11'. United States Environmental Protection Agency, Office of Pollution Prevention and Toxics, Washington DC (2012).
Deviations:
not applicable
GLP compliance:
no
Remarks:
not required
Test material information:
Composition 1
Test organisms (species):
other: green algae
Total exposure duration:
72 h
Key result
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
1.8 mg/L
Nominal / measured:
estimated
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: log Kow 2.82; ECOSAR Class: Esters
Validity criteria fulfilled:
yes
Remarks:
The ECOSAR-Ester equation is valid when using the OECD criteria. In addition, N=13 and R2 is 0.74
Conclusions:
The 72h-ErC10 of the substance to green algae is 1.8 mg/L.
Executive summary:

The long-term algae toxicity value for the ester Herbacet #1 is predicted to be 1.8 mg/L based on the ECOSAR SAR for esters using an estimated log Kow of 2.82, molecular weight of 166.2 and the equation: Log 96h ChV (mmol/L) = -0.5583 (log Kow) - 0.4017. The endpoint is considered equivalent to the 72h-ErC10/NOEC as defined in OECD TG 201.

Herbacet #1 is in the applicability domain of the ECOSAR prediction because: a) Herbacet #1 is an ester; b) its log Kow is 2.82 (=< 8.0); c) its MW is 166.2 (< 1000); and; d) the toxicity predicted is below its measured water solubility of 739 mg/L.

The measured and predicted log Kow’s of Herbacet #1 are very similar (2.8 and 2.82, respectively). The closest analogue in the training set is Octyl lactate, with a log Kow of 2.8 and a molecular weight of 202. The predicted long-term algae toxicity value is 2.3 mg/L while the measured value is 3.2 mg/L, presenting the limited uncertainty of the prediction for Octyl lactate and therefore for Herbacet #1.

The fit in the applicability domain and the availability of an analogue in the training set results in limited uncertainty of the Herbacet #1 prediction. This shows that the prediction is reliable and a Klimisch 2 can be assigned. In accordance with REACH Annex XI, the validity of the (Q)SAR is documented in a QMR for chronic algae toxicity on esters. The adequate and reliable documentation, presented in the Attached justification section, further supports this prediction.

Description of key information

Short-term toxicity to algae:

The acute algae ErC50 for the ester Herbacet #1 is predicted to be 5.3 mg/L based on the ECOSAR SAR for esters using an estimated log Kow of 2.82, molecular weight of 166.2 and the equation: Log 96-h EC50 (mmol/L) = -0.6993 (log Kow) + 0.4715. The 96h-EC50 is considered equivalent to the 72h ErC50 as defined in OECD TG 201.

Herbacet #1 is in the applicability domain of the ECOSAR prediction because: a) Herbacet #1 is an ester; b) its log Kow is 2.82 (=< 6.4); c) its MW is 166.2 (< 1000); and; d) the toxicity predicted is below its measured water solubility of 739 mg/L.

The measured and predicted log Kow’s of Herbacet #1 are very similar (2.8 and 2.82, respectively). The closest analogue in the training set is Octyl lactate, with a log Kow of 2.8 and a molecular weight of 202. The predicted EC50 value of this ECOSAR analogue is 7.0 mg/L and the measured value is 7.6 mg/L, presenting the limited uncertainty of the prediction for Octyl lactate and therefore for Herbacet #1.

The fit in the applicability domain and the availability of an analogue in the training set results in limited uncertainty of the Herbacet #1 prediction. This shows that the prediction is reliable and a Klimisch 2 can be assigned. In accordance with REACH Annex XI, the validity of the (Q)SAR is documented in a QMR for acute algae toxicity on esters. The adequate and reliable documentation, presented in the Attached justification section of the study record for Short-term toxicity to algae, further supports this prediction.

Long-term toxicity to algae:

The long-term algae toxicity value for the ester Herbacet #1 is predicted to be 1.8 mg/L based on the ECOSAR SAR for esters using an estimated log Kow of 2.82, molecular weight of 166.2 and the equation: Log 96h ChV (mmol/L) = -0.5583 (log Kow) - 0.4017. The endpoint is considered equivalent to the 72h-ErC10/NOEC as defined in OECD TG 201.

Herbacet #1 is in the applicability domain of the ECOSAR prediction because: a) Herbacet #1 is an ester; b) its log Kow is 2.82 (=< 8.0); c) its MW is 166.2 (< 1000); and; d) the toxicity predicted is below its measured water solubility of 739 mg/L.

The measured and predicted log Kow’s of Herbacet #1 are very similar (2.8 and 2.82, respectively). The closest analogue in the training set is Octyl lactate, with a log Kow of 2.8 and a molecular weight of 202. The predicted long-term algae toxicity value is 2.3 mg/L while the measured value is 3.2 mg/L, presenting the limited uncertainty of the prediction for Octyl lactate and therefore for Herbacet #1.

The fit in the applicability domain and the availability of an analogue in the training set results in limited uncertainty of the Herbacet #1 prediction. This shows that the prediction is reliable and a Klimisch 2 can be assigned. In accordance with REACH Annex XI, the validity of the (Q)SAR is documented in a QMR for chronic algae toxicity on esters. The adequate and reliable documentation, presented in the Attached justification section of the study record for Long-term toxicity to algae, further supports this prediction.

Key value for chemical safety assessment

EC50/LC50 for freshwater algae:
5.3 mg/L
EC10, LC10 or NOEC for freshwater algae:
1.8 mg/L

Additional information