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Toxicity to aquatic algae and cyanobacteria

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Endpoint:
toxicity to aquatic algae and cyanobacteria
Remarks:
EC10/NOEC
Type of information:
(Q)SAR
Adequacy of study:
key study
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 chronic algae ErC10 for the neutral organic substance Octacetal is predicted to be 3.13 mg/L based on the ECOSAR SAR for neutral organics using an estimated Log Kow of 3.17, a molecular weight (MW) of 174.28 and the equation: 72-96h ErC10 (mg/L) = MW *10^(-0.6029 (Log Kow) + 0.1648).
Octacetal is in the applicability domain of the ECOSAR prediction because: a) Octacetal is an acetal presenting the toxicity solely by its bioavailability (i.e. without fragments that activate this acetal); b) its estimated Log Kow is 3.17 (=< 8.0); c) its MW is 174.28 (=< 1000); and d) the toxicity predicted is below its water solubility of 210.5 mg/L.
A fairly close analogue available in the ECOSAR training set is 2-Ethylhexanol (CAS# 104-76-7), with an estimated Log Kow of 2.7, a molecular weight of 130 and is also a neutral organic. The predicted value is 4.29 mg/L while the measured value is 2.0 mg/L, supporting the reliability of the prediction.
The fit in the applicability domain and the availability of an analogue in the training set results in limited uncertainty of the Octacetal 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 neutral organics (see attached report). The adequate and reliable documentation, presented in the study record, further supports this prediction.
Reference:
Composition 1
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 Programm MS Windows v1.11'. United States Environmental Protection Agency, Office of Pollution Prevention and Toxics, Washington DC (2012).
GLP compliance:
no
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:
EC10
Effect conc.:
3.13 mg/L
Nominal / measured:
estimated
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: ECOSAR Class: Neutral Organics
Validity criteria fulfilled:
yes
Remarks:
The substance is in the applicability domain of the model.
Conclusions:
The ErC10 is 3.13 mg/L
Executive summary:

The chronic algae ErC10 for the neutral organic substance Octacetal is predicted to be 3.13 mg/L based on the ECOSAR SAR for neutral organics using an estimated Log Kow of 3.17, a molecular weight (MW) of 174.28 and the equation: 72-96h ErC10 (mg/L) = MW *10^(-0.6029 (Log Kow) + 0.1648).

Octacetal is in the applicability domain of the ECOSAR prediction because:  a) Octacetal is an acetal presenting the toxicity solely by its bioavailability (i.e. without fragments that activate this acetal); b) its estimated Log Kow is 3.17 (=< 8.0); c) its MW is 174.28 (=< 1000); and d) the toxicity predicted is below its water solubility of 210.5 mg/L.

A fairly close analogue available in the ECOSAR training set is 2-Ethylhexanol (CAS# 104-76-7), with an estimated Log Kow of 2.7, a molecular weight of 130 and is also a neutral organic. The predicted value is 4.29 mg/L while the measured value is 2.0 mg/L, supporting the reliability of the prediction.

The fit in the applicability domain and the availability of an analogue in the training set results in limited uncertainty of the Octacetal 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 neutral organics (see attached report). The adequate and reliable documentation, presented in the study record, further supports this prediction.

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
(Q)SAR
Adequacy of study:
key study
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
Remarks:
QSAR
Justification for type of information:
The acute algae ErC50 for the neutral organic substance Octacetal is predicted to be 9.39 mg/L based on the ECOSAR SAR for neutral organics using an estimated Log Kow of 3.17, a molecular weight (MW) of 174.28 and the equation: 72-96h ErC50(mg/L) = MW * 10^( -0.6922 (Log Kow) + 0.9253) .
Octacetal is in the applicability domain of the ECOSAR prediction because: a) Octacetal is an acetal presenting the toxicity solely by its bioavailability (i.e. without fragments that activate this acetal); b) its estimated Log Kow is 3.17 (=< 6.4); c) its MW is 174.28 (=< 1000); and d) the toxicity predicted is below its predicted water solubility of 210.5 mg/L.
A fairly close analogue available in the ECOSAR training set is 2-Ethylhexanol (CAS 104-76-7) with an estimated Log Kow of 2.7 and molecular weight of 130, with an experimental toxicity of 12 mg/L and an ECOSAR prediction of 14.1 mg/L, presenting the limited uncertainty of the prediction of 2-Ethylhexanol and therefore also for Octacetal.
The fit in the applicability domain and the availability of an analogue in the training set results in limited uncertainty of the Octacetal 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 neutral organics (see attached report). The adequate and reliable documentation, presented in the study record, further supports this prediction.
Reference:
Composition 1
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 Programm MS Windows v1.11'. United States Environmental Protection Agency, Office of Pollution Prevention and Toxics, Washington DC (2012).
GLP compliance:
no
Test material information:
Composition 1
Test organisms (species):
other: green algae
Water media type:
freshwater
Total exposure duration:
72 h
Remarks on exposure duration:
Based on current OECD TG 201 information (on which the QSAR is derived)
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
9.39 mg/L
Nominal / measured:
estimated
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: ECOSAR class: Neutral organics
Validity criteria fulfilled:
yes
Remarks:
The substance is in the applicability domain of the model.
Conclusions:
The acute algae toxicity, ErC50, is 9.39 mg/L.
Executive summary:

The acute algae ErC50 for the neutral organic substance Octacetal is predicted to be 9.39 mg/L based on the ECOSAR SAR for neutral organics using an estimated Log Kow of 3.17, a molecular weight (MW) of 174.28 and the equation: 72-96h ErC50(mg/L) = MW * 10^( -0.6922 (Log Kow) + 0.9253).

Octacetal is in the applicability domain of the ECOSAR prediction because:  a) Octacetal is an acetal presenting the toxicity solely by its bioavailability (i.e. without fragments that activate this acetal); b) its estimated Log Kow is 3.17 (=< 6.4); c) its MW is 174.28 (=< 1000); and d) the toxicity predicted is below its predicted water solubility of 210.5 mg/L.

A fairly close analogue available in the ECOSAR training set is 2-Ethylhexanol  (CAS 104-76-7) with an estimated Log Kow of  2.7 and molecular weight of 130, with an experimental toxicity of 12 mg/L and an ECOSAR prediction of 14.1 mg/L, presenting the limited uncertainty of the prediction of 2-Ethylhexanol and therefore also for Octacetal.

The fit in the applicability domain and the availability of an analogue in the training set results in limited uncertainty of the Octacetal 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 neutral organics (see attached report). The adequate and reliable documentation, presented in the study record, further supports this prediction.

Description of key information

Acute freshwater algae: ECOSAR-Neutral organics: ErC50 = 9.39 mg/L

Long-term freshwater algae: ECOSAR-Neutral organics: ErC10 = 3.13 mg/L

Key value for chemical safety assessment

EC50/LC50 for freshwater algae:
9.39 mg/L
EC10, LC10 or NOEC for freshwater algae:
3.13 mg/L

Additional information