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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:
supporting study
Study period:
2014-06-23 to 2014-06-25
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: QSAR value. The substance falls into the applicability domains of the model QSAR.
Justification for type of information:
QSAR prediction: migrated from IUCLID 5.6
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
yes
Remarks:
QSAR model
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, based on validated data derived from 72-hour ErC50 tests on algae, for which the concentrations of the test item had been determined by chemical analyses over the test period. The QSAR is a simple linear regression of sub-cooled liquid solubility versus 72-h ErC50 for algae and is valid within the applicability domain defined in the QMRF.
GLP compliance:
no
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
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: QSAR method
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Remarks on exposure duration:
72h-ErC50
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 QSAR is based on data from studies performed at between 14 - 25 °C (depending on the species considered)
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:
The QSAR is based on data from studies performed on freshwater species
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
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
0.45 mg/L
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 95% CL [0.26-0.78]
Details on results:
not applicable
Results with reference substance (positive control):
not applicable
Reported statistics and error estimates:
95% CL [0.26-0.78]
QSAR statistical parameters are given in the QMRF and the QPRF

not data

Validity criteria fulfilled:
yes
Remarks:
The substance falls into applicability domains of the QSAR model
Conclusions:
72h-ErC50 for β-pinene = 0.45 mg test item/L with 95%-Confidence Limit of 0.26-0.78 mg test item/L
Executive summary:

The acute toxicity to aquatic algae was determined using a validated QSAR for the Mode of Action in question, based on validated data derived from 72-hour ErC50 tests on algae, for which the concentrations of the test item had been determined by chemical analyses over the test period. The QSAR is a simple linear regression of sub-cooled liquid solubility versus 72-h ErC50 for algae and is valid within the applicability domain defined in the QMRF.

The acute toxicity to algae of beta-pinene has been investigated using a QSAR model that predicts daphnia mortality in an OECD 201 study. Beta-pinene falls within the applicability domain of the model as demonstrated in the QPRF.

The 72-h ErC50 was 0.45 mg test material/L with 95%-Confidence Limit between 0.26 and 0.78 mg test material/L. EC50 were based on growth rate. 

Based on the results of this study, beta-pinene would 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: QSAR model

ErC50: 0.45 mg test material/L 95%-C.L.: 0.26 to 0.78 mg test material/L

 

 

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
4 (not assignable)
Rationale for reliability incl. deficiencies:
other: Study conducted according to OECD Guideline 201 but with deviations: no detail on material and methods
Reason / purpose for cross-reference:
reference to same study
Reason / purpose for cross-reference:
reference to other study
Qualifier:
according to guideline
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
yes
Remarks:
no detail on material and methods
GLP compliance:
not specified
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
No details on properties of test surrogate or analogue material
Analytical monitoring:
not specified
Details on sampling:
No details on sampling
Vehicle:
not specified
Details on test solutions:
No details on test solution
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
No data
Test type:
not specified
Water media type:
not specified
Limit test:
no
Total exposure duration:
72 h
Post exposure observation period:
No data
Hardness:
No data
Test temperature:
No data
pH:
No data
Dissolved oxygen:
No data
Salinity:
No data
Nominal and measured concentrations:
No data
Details on test conditions:
No data
Reference substance (positive control):
not specified
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 1.6 mg/L
Nominal / measured:
not specified
Conc. based on:
not specified
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
1.6 mg/L
Nominal / measured:
not specified
Conc. based on:
not specified
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 21 mg/L
Nominal / measured:
not specified
Conc. based on:
not specified
Basis for effect:
cell number
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
> 21 mg/L
Nominal / measured:
not specified
Conc. based on:
not specified
Basis for effect:
cell number
Details on results:
No data
Results with reference substance (positive control):
No data
Reported statistics and error estimates:
No data

None

Validity criteria fulfilled:
not specified
Conclusions:
Under the test conditions, the 72h-NOEC of dipentene was 1.6 mg/L, based on growth rate.
Executive summary:

As there is no detail on test material and conditions, this study was classified with a reliability of 4.

Under the test conditions, the 72h-NOEC of dipentene was 1.6 mg/L, based on growth rate.

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
(Q)SAR
Adequacy of study:
supporting study
Study period:
2014-05-23 to 2014-05-23
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: QSAR value. The substance falls into the applicability domains of the model QSAR.
Justification for type of information:
QSAR prediction: migrated from IUCLID 5.6
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
yes
Remarks:
QSAR model
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, based on validated data derived from 72-hour ErC50 tests on algae, for which the concentrations of the test item had been determined by chemical analyses over the test period. The QSAR is a simple linear regression of sub-cooled liquid solubility versus 72-h ErC50 for algae and is valid within the applicability domain defined in the QMRF.
GLP compliance:
no
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
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: QSAR method
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Remarks on exposure duration:
72h-ErC50
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 QSAR is based on data from studies performed at between 14 - 25 °C (depending on the species considered)
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:
The QSAR is based on data from studies performed on freshwater species
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
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
5.52 mg/L
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 95% CL [3.43-9.33]
Details on results:
not applicable
Results with reference substance (positive control):
not applicable
Reported statistics and error estimates:
95% CL [3.43-9.33]
QSAR statistical parameters are given in the QMRF and the QPRF

not data

Validity criteria fulfilled:
yes
Remarks:
The substance falls into applicability domains of the QSAR model
Conclusions:
72h-ErC50 for Bornyl acetate = 5.52 mg test item/L with 95%-Confidence Limit of 3.43-9.33 mg test item/L
Executive summary:

The acute toxicity to aquatic algae was determined using a validated QSAR for the Mode of Action in question, based on validated data derived from 72-hour ErC50 tests on algae, for which the concentrations of the test item had been determined by chemical analyses over the test period. The QSAR is a simple linear regression of sub-cooled liquid solubility versus 72-h ErC50 for algae and is valid within the applicability domain defined in the QMRF.

The acute toxicity to algae of Bornyl acetate has been investigated using a QSAR model that predicts daphnia mortality in an OECD 201 study. Bornyl acetate falls within the applicability domain of the model as demonstrated in the QPRF.

The 72-h ErC50 was 5.52 mg test material/L with 95%-Confidence Limit between 3.43 and 9.33 mg test material/L. EC50 were based on growth rate. 

Based on the results of this study, Bornyl acetate 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: QSAR model

ErC50: 5.52 mg test material/L 95%-C.L.: 3.43 to 9.33 mg test material/L

 

 

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
(Q)SAR
Adequacy of study:
supporting study
Study period:
2014-05-23 to 2014-05-23
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: QSAR value. The substance falls into the applicability domains of the model QSAR.
Justification for type of information:
QSAR prediction: migrated from IUCLID 5.6
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
yes
Remarks:
QSAR model
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, based on validated data derived from 72-hour ErC50 tests on algae, for which the concentrations of the test item had been determined by chemical analyses over the test period. The QSAR is a simple linear regression of sub-cooled liquid solubility versus 72-h ErC50 for algae and is valid within the applicability domain defined in the QMRF.
GLP compliance:
no
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
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: QSAR method
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Remarks on exposure duration:
72h-ErC50
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 QSAR is based on data from studies performed at between 14 - 25 °C (depending on the species considered)
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:
The QSAR is based on data from studies performed on freshwater species
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
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
0.45 mg/L
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 95% CL [0.26-0.78]
Details on results:
not applicable
Results with reference substance (positive control):
not applicable
Reported statistics and error estimates:
95% CL [0.26-0.78]
QSAR statistical parameters are given in the QMRF and the QPRF

not data

Validity criteria fulfilled:
yes
Remarks:
The substance falls into applicability domains of the QSAR model
Conclusions:
72h-ErC50 for camphene = 0.45 mg test item/L with 95%-Confidence Limit of 0.26-0.78 mg test item/L
Executive summary:

The acute toxicity to aquatic algae was determined using a validated QSAR for the Mode of Action in question, based on validated data derived from 72-hour ErC50 tests on algae, for which the concentrations of the test item had been determined by chemical analyses over the test period. The QSAR is a simple linear regression of sub-cooled liquid solubility versus 72-h ErC50 for algae and is valid within the applicability domain defined in the QMRF.

The acute toxicity to algae of camphene has been investigated using a QSAR model that predicts daphnia mortality in an OECD 201 study. Camphene falls within the applicability domain of the model as demonstrated in the QPRF.

The 72-h ErC50 was 0.45 mg test material/L with 95%-Confidence Limit between 0.26 and 0.78 mg test material/L. EC50 were based on growth rate. 

Based on the results of this study, camphene would 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: QSAR model

ErC50: 0.45 mg test material/L 95%-C.L.: 0.26 to 0.78 mg test material/L

 

 

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
(Q)SAR
Adequacy of study:
supporting study
Study period:
2014-05-23 to 2014-05-23
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: QSAR value. The substance falls into the applicability domains of the model QSAR.
Justification for type of information:
QSAR prediction: migrated from IUCLID 5.6
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
yes
Remarks:
QSAR model
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, based on validated data derived from 72-hour ErC50 tests on algae, for which the concentrations of the test item had been determined by chemical analyses over the test period. The QSAR is a simple linear regression of sub-cooled liquid solubility versus 72-h ErC50 for algae and is valid within the applicability domain defined in the QMRF.
GLP compliance:
no
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
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: QSAR method
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Remarks on exposure duration:
72h-ErC50
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 QSAR is based on data from studies performed at between 14 - 25 °C (depending on the species considered)
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:
The QSAR is based on data from studies performed on freshwater species
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
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
0.45 mg/L
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 95% CL [0.26-0.78]
Details on results:
not applicable
Results with reference substance (positive control):
not applicable
Reported statistics and error estimates:
95% CL [0.26-0.78]
QSAR statistical parameters are given in the QMRF and the QPRF

not data

Validity criteria fulfilled:
yes
Remarks:
The substance falls into applicability domains of the QSAR model
Conclusions:
72h-ErC50 for α-pinene = 0.45 mg test item/L with 95%-Confidence Limit of 0.26-0.78 mg test item/L
Executive summary:

The acute toxicity to aquatic algae was determined using a validated QSAR for the Mode of Action in question, based on validated data derived from 72-hour ErC50 tests on algae, for which the concentrations of the test item had been determined by chemical analyses over the test period. The QSAR is a simple linear regression of sub-cooled liquid solubility versus 72-h ErC50 for algae and is valid within the applicability domain defined in the QMRF.

The acute toxicity to algae of α-pinene has been investigated using a QSAR model that predicts daphnia mortality in an OECD 201 study. α-pinene falls within the applicability domain of the model as demonstrated in the QPRF.

The 72-h ErC50 was 0.45 mg test material/L with 95%-Confidence Limit between 0.26 and 0.78 mg test material/L. EC50 were based on growth rate. 

Based on the results of this study, α-pinene would 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: QSAR model

ErC50: 0.45 mg test material/L 95%-C.L.: 0.26 to 0.78 mg test material/L

 

 

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
calculation (if not (Q)SAR)
Remarks:
Migrated phrase: estimated by calculation
Adequacy of study:
key study
Study period:
2014-05-23 to 2014-05-26
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Calculation method is used ; calculation method applicable for the endpoint.
Qualifier:
equivalent or similar to guideline
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:
Details on properties of test surrogate or analogue material (migrated information):
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 but extremely low or high temperatures could influence the solubility of certain constituents. Therefore, the calculation method is considered acceptable to determine EL50s for algae between 12 and 28°C.
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. However as the fish QSAR for the constituents calculation was based on data from freshwater studies, the resulting calculation is considered valid for freshwater organisms
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:
EL50
Effect conc.:
4 mg/L
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EL50
Effect conc.:
3.7 mg/L
Conc. based on:
test mat.
Basis for effect:
growth rate
Details on results:
not applicable
Results with reference substance (positive control):
not applicable
Reported statistics and error estimates:
not applicable

Table 1: Expected concentrations at this 72h-ErL50 (composition 1: typical composition)

constituents

concentration in the WAF (mg.L-1)

limonene

0.79

α-pinene

1.21

β-pinene

0.61

camphene

0.49

Table 2: Expected concentrations at this 72h-ErL50 (composition 2 : theoretical worst case composition)

constituents

concentration in the WAF (mg.L-1)

limonene

0.81

α-pinene

1.17

β-pinene

0.77

camphene

0.37

bornyl acetate

0.04

Validity criteria fulfilled:
yes
Conclusions:
72h-ErL50 for typical composition of Fir silver oil = 4.0 mg test item/L and 72h-ErL50 for theoritecal worst composition of Fir silver oil is 3.7 mg test item/L.
Executive summary:

Fir Silver oil is a Natural Complex Substance (UVCB) with a well-defined composition for which the relative percentage and its reported variation of each constituent is known. 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). Two compositions have been investigated, the “typical” composition proposed by the Lead registrant and a theoretical worst case composition, derived from data supplied in the SIP that maximizes the concentration of the most toxic constituents.

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 EC50s 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 4.0 mg test material/L for the typical composition of Fir Silver oil, and the 72-h ErL50 was 3.7 mg test material/L for the theoretical worst case composition. ErL50 were based on growth rate.

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

 

Results Synopsis

Test Type: Calculation method

ErL50: 4.0 mg test material/L for typical composition

ErL50: 3.7 mg test material/L for theoretical worst case composition

 

Description of key information

Fir Silver oil (Fir, Abies alba, ext.)  is a Natural Complex Substance (UVCB) with a well-defined composition for which the relative percentage and its reported variation of each constituent is known. The acute toxicity to aquatic algae property has been investigated using an in-house calculation method that mimics an OECD 201 study and guideline for Testing of Chemicals No. 23 (i.e. WAF conditions) (details are given below). Two theoretical compositions have been investigated, the “typical” composition proposed by the Lead registrant and a theoretical worst case composition that maximizes the concentration of the most toxic constituents. The 72-h ErL50 was 4.0 mg test material/L, and the 72-h ErL50 was 3.7 mg test material/L for the theoretical worst case composition. ErL50 were based on growth rate.

Key value for chemical safety assessment

EC50 for freshwater algae:
3.7 mg/L

Additional information

Fir Silver oil (Fir, Abies alba, ext.) is a Natural Complex Substance (UVCB) with a well-defined composition for which the relative percentage of each constituent is known. Therefore, it has been decided that the ecotoxicity Fir Silver oil (Fir, Abies alba, ext.) will be derived from knowledge of the constituents.  The mixture ecotoxicity properties may be derived from the ecotoxicity of the individual constituents using the CLP additivity calculation approach.

 However, it has been observed that CLP additivity calculations for mode of action 1 compounds are unreasonably conservative when compared to classic WAF studies, and this has been proved in a number of cases for natural complex substances. Indeed, natural extract compositions are a mixture of hydrophilic alcohol molecules and hydrophobic terpene molecules. Therefore, when a WAF is performed most of substances fully dissolved in the aqueous phase are the hydrophilic fraction while the hydrophobic fraction (the more toxic elements for MOA 1 substances) may be below their water solubility value. 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. On the other hand the CLP additivity approach is calculated on the basis that all the substances are at their maximum solubility.

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.

These two reasons explain why ecotoxicity values from WAF studies are always higher for non-polar narcotic mixtures than the calculated values from CLP additivity calculation.

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 4.0 mg test material/L for the typical composition of Fir Silver oil, and the 72-h ErL50 was 3.7mg test material/L for the theoretical worst case composition. ErL50 were based on growth rate.

 

The in-house calculation has been designed to mimic the behaviour of the mixture in a WAF test where the final toxicity is calculated by additivity of the residual bioavailable fraction of each constituent. This approach has been validated using a Natural Complex Substance similar to Fir Silver oil (Fir, Abies alba, ext.) (Details on the validations are available in the attached position paper). This calculation is therefore more accurate than the CLP method accurate but remains conservative compared to the experimental value.

 

Based on the results of this study, Fir Silver oil (Fir, Abies alba, ext.) would not be classified as acutely toxic to aquatic organisms in accordance with the classification of the CLP.

This toxicity prediction has been validated and is considered acceptable to fulfil the aquatic algae toxicity endpoint.