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Toxicity to aquatic algae and cyanobacteria

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Reference
Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
calculation (if not (Q)SAR)
Remarks:
Estimated by calculation
Adequacy of study:
key study
Study period:
2017-03-16 to 2017-03-17
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
accepted calculation method
Remarks:
Calculation method is used; calculation method applicable for that endpoint.
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
yes
Remarks:
calculation method
Principles of method if other than guideline:
The acute toxicity to aquatic algae was determined using a validated QSAR for the Mode of Action in question. The first step of the iSafeRat mixture toxicity calculation employs phase equilibrium thermodynamics in order to determine the concentrations of each constituent within the WAF. This fraction equates to the analysable fraction of a WAF study.
Within the WAF, the constituents also partition between themselves further reducing the bioavailable fraction and thus the toxicity of the mixture compared to the individual constituents. In the calculation the second step is to remove this non-bioavailable fraction.
The final step is to determine the truly bioavailable fraction of the WAF per constituent. The ErC50s of each constituent are already known from literature or calculated using the iSafeRat QSAR model. Each value and calculation has been included as a supporting study in the IUCLID. An additivity approach (based on Chemical Activity of each constituent) is used in order to calculate the Effective Loading rate of the WAF.
The method has been validated using data derived from 72-hour ErC50 tests on aquatic algae, for which the concentrations of the test item had been determined by chemical analyses over the test period. Further to this the effective loading rate of the WAF is determined by using a series of calculation steps using phase equilibrium thermodynamics and excluding the non-bioavailable fraction.
GLP compliance:
no
Specific details on test material used for the study:
Not applicable
Analytical monitoring:
no
Details on sampling:
not applicable
Vehicle:
no
Details on test solutions:
not applicable
Test organisms (species):
other: algae spp.
Details on test organisms:
not applicable
Test type:
other: calculation method
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Remarks on exposure duration:
72h-ErL50 (effective loading rate of WAF)
Post exposure observation period:
not applicable
Hardness:
Hardness is not a necessary component of the WAF calculation
Test temperature:
The Temperature is not a necessary component of the WAF calculation
pH:
The pH is not a necessary component of the WAF calculation
Dissolved oxygen:
The oxygen concentration is not a necessary component of the WAF calculation
Salinity:
Salinity is not a necessary component of the WAF calculation.
Nominal and measured concentrations:
The calculation determines measured concentrations
Details on test conditions:
calculation method
Reference substance (positive control):
not required
Duration:
72 h
Dose descriptor:
other: ErL50
Remarks:
effective loading rate of WAF
Effect conc.:
18 mg/L
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other:
Remarks:
Based on a typical composition
Details on results:
not applicable
Results with reference substance (positive control):
not applicable
Reported statistics and error estimates:
not applicable

At this loading rate, the expected concentrations of each constituent in the mixture (based on thermodynamic calculation) are as follows:

constituents

concentration in the WAF (mg.L-1)

linalyl acetate

12

linalool

2.0

germacrene D

0.0075

α-terpineol

0.55

β-caryophyllene

0.0023

geranyl acetate

0.16

geraniol

0.15

β-myrcene

0.045

neryl acetate

0.10

β-ocimene

0.056

sclareol

0.092

α-copaene

0.00048

Validity criteria fulfilled:
yes
Conclusions:
72h-ErL50 for the typical composition of Clary sage oil: 18 mg test item/L.
Executive summary:

Clary sage oil is a Natural Complex Substance (UVCB) with a well-defined composition. Its acute toxicity to aquatic algae property has been investigated using an in-house calculation method that replaces an OECD 201 study and guideline for Testing of Chemicals No. 23 (i.e. WAF conditions).

The typical composition has been investigated.

The first step of the iSafeRat mixture toxicity calculation employs phase equilibrium thermodynamics in order to determine the concentrations of each constituent within the WAF. This fraction equates to the analyzable fraction of a WAF study.

Within the WAF, the constituents also partition between themselves further reducing the bioavailable fraction and thus the toxicity of the mixture compared to the individual constituents. In the calculation the second step is to remove this non-bioavailable fraction.

The final step is to determine the truly bioavailable fraction of the WAF per constituent. The ErC50s of each constituent are already known from literature or calculated using the iSafeRat QSAR model. Each value and calculation has been included as a supporting study in the IUCLID. An additivity approach (based on Chemical Activity of each constituent) is used in order to calculate the Effective Loading rate of the WAF.

Using this approach, the 72-h ErL50 was 18 mg test material/L for the typical composition of Clary sage oil. ErL50 was based on growth rate.

Based on the results of this study, Clary sage oil oil would not be classified as acute 1 to aquatic organisms in accordance with the classification of the CLP.

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

 

Results Synopsis

Test Type: Calculation method

ErL50: 18 mg test material/L for the typical composition

Description of key information

72h-ErL50 for typical composition of Clary Sage Oil is 18 mg test item/L.

Based on the results of this study, Clary Sage oil would not be classified as acute 1 to aquatic organisms in accordance with the classification of the CLP.

Key value for chemical safety assessment

EC50 for freshwater algae:
18 mg/L

Additional information

The acute toxicity to aquatic algae of the UVCB Clary Sage Oil has been investigated using a reliable in-house calculation method that replaces an OECD 201 study and guideline for Testing of Chemicals No. 23 (i.e. WAF conditions). The algorithm used is based on a QSAR model which has been validated to be compliant with the OECD recommendations for QSAR modeling (OECD, 2004).

The typical composition has been investigated.

The first step of the iSafeRat mixture toxicity calculation employs phase equilibrium thermodynamics in order to determine the concentrations of each constituent within the WAF. This fraction equates to the analyzable fraction of a WAF study. Within the WAF, the constituents also partition between themselves further reducing the bioavailable fraction and thus the toxicity of the mixture compared to the individual constituents. In the calculation the second step is to remove this non-bioavailable fraction. The final step is to determine the truly bioavailable fraction of the WAF per constituent. The ErC50s of each constituent are already known from literature or predicted using the iSafeRat QSAR model. Each value has been included as a supporting study in the IUCLID. An additivity approach (based on Chemical Activity of each constituent) is used in order to calculate the Effective Loading rate of the WAF.

Based on the results of this study, Clary Sage oil would not be acutely toxic to aquatic organisms in accordance with the classification of the CLP.

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