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Ecotoxicological information

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:
2017-01-27 to 2017-01-31
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
accepted calculation method
Remarks:
Calculation method is used; calculation method applicable for that endpoint.
Justification for type of information:
See attached document for full details
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 predicted using the iSafeRat QSAR model. Each value as well as QMRF/QPRF are provided 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
Key result
Duration:
72 h
Dose descriptor:
EL50
Effect conc.:
13 mg/L
Conc. based on:
test mat.
Remarks:
effective loading rate of WAF
Basis for effect:
growth rate
Remarks on result:
other:
Remarks:
Based on a typical composition of carrot seeds oil rich in carotol
Duration:
72 h
Dose descriptor:
EL50
Effect conc.:
14 mg/L
Conc. based on:
test mat.
Remarks:
effective loading rate of WAF
Basis for effect:
growth rate
Remarks on result:
other: Based on typical composition of carrot seeds oil rich in geraniol
Details on results:
not applicable
Results with reference substance (positive control):
not applicable
Reported statistics and error estimates:
not applicable

Determination of the Analytically Measurable Aqueous Phase (AMAP).

Using the model, the specific concentration of each constituent in the WAF can be accurately determined at any loading rate taking into account the original composition of the mixture and the new corrected limit of solubility of each constituent. The sum of these concentrations, the AMAP, is equivalent to the concentration of all constituents that would be measured in a WAF test. For a given loading rate, the loaded concentration of each constituent is compared to its respective solubility limit. If one is higher than the solubility limit then it is considered that the concentration of the constituent will be equal to its solubility limit. If lower, the true loading concentration is considered.Provided this adapted water solubility limits for each consitutents. analytically measurable concentrations in aqueous solutions expected from known WAF loading rates of characterised mixtures can be calculated.

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

Analytically Measured Aqueous Phase (AMAP) calculated at the predicted ErL50.

 

Concentration in the WAF

(mg test item.L-1)

Constituents

for Carrot Seeds oil

(rich in carotol)

for Carrot Seeds oil

(rich in geraniol)

constituent 1

7.3

4.1

constituent 2

0.94

0.69

constituent 3

0.35

0.32

constituent 4

0.0029

0.0033

constituent 5

0.0022

0.0012

constituent 6

0.0029

0.32

constituent 7

0.20

0.048

constituent 8

0.19

0.11

constituent 9

0.12

0.064

constituent 10

0.13

0.047

constituent 11

0.0011

-

constituent 12

0.00039

0.00036

constituent 13

0.11

0.074

constituent 14

0.088

0.43

constituent 15

0.12

0.14

constituent 16

-

1.2

constituent 17

-

1.1

constituent 18

-

0.0015

constituent 19

-

0.00046

constituent 20

-

0.090

Validity criteria fulfilled:
yes
Conclusions:
The following toxicity values have been found for the two qualities of the registered substance Carrot seeds oil:
- Carrot seeds oil rich in carotol: 72h-ErL50 = 13 mg/L
- Carrot seeds oil rich in geraniol: 72h-ErL50 = 14 mg/L
Executive summary:

Carrot seed 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 supplied by the lead registrant 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 estimated using the iSafeRat QSAR model. Each value as well as QMRF/QPRF are provided in the dataset. 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 13 mg test material/L for the quality rich in carotol and it was 14 mg/L for the quality rich in geraniol. ErL50 values were based on growth rate.

Description of key information

Based on a calculation method, the following toxicity values have been found for the two qualities of the registered substance Carrot seeds oil:

- Carrot seeds oil rich in carotol: 72h-ErL50 = 13 mg/L

- Carrot seeds oil rich in geraniol: 72h-ErL50 = 14 mg/L

For the registered substance, the key 48h-EL50 value selected for that endpoint is therefore 13 mg/L (most conservative value between the two qualities).

Key value for chemical safety assessment

EC50 for freshwater algae:
13 mg/L

Additional information

For that endpoint, one study with the registered substance was available. indeed, the toxicity to aquatic algae of Carrot Seeds oil 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 compositions of the two qualities of the substance have been investigated and therefore, one prediction has been realised for each quality. The algorithm used for the purpose of this study is based on a QSAR model which has been validated to be compliant with the OECD recommendations for QSAR modeling (OECD, 2004).

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. 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 were predicted using the iSafeRat QSAR model and the QMRF/QPRF have been attached to the dossier:

constituents

72h-ErC50(mg.L-1) used

constituent 1

4.0

constituent 2

0.66

constituent 3

0.99 

constituent 4

> solubility limit

constituent 5

> solubility limit

constituent 6

> solubility limit

constituent 7

1.0

constituent 8

56

constituent 9

1.1

constituent 10

0.60

constituent 11

> solubility limit

constituent 12

> solubility limit

constituent 13

0.50

constituent 14

1.9

constituent 15

0.64

constituent 16

24

constituent 17

2.2

constituent 18

> solubility limit

constituent 19

> solubility limit

constituent 20

62

Then, an additivity approach (based on Chemical Activity of each constituent) is used in order to calculate the Effective Loading rate of the WAF.

The result below are the toxicity values anticipated during a 72-hour ErL50 study on algae based on the two compositions of CARROT SEEDS OIL. The 72-hour ErL50 are calculated as follows:

Composition

Time (h)

ErL50(mg test item.L-1)

Carrot Seeds oil
(rich in carotol)

72

13

Carrot Seeds oil
(rich in geraniol)

72

14

For that endpoint, the most conservative value between both qualities has been selected as the key value for the registered substance. Therefore, the 72h-ErL50 of Carrot seeds oil is expected to be 13 mg/L.

Based on the results of this study, the substance 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.