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Ecotoxicological information

Short-term toxicity to aquatic invertebrates

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Reference
Endpoint:
short-term toxicity to aquatic invertebrates
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 the endpoint
Justification for type of information:
See attached documents for full details
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Deviations:
yes
Remarks:
calculation method
Principles of method if other than guideline:
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 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 48-hour EC50 tests on aquatic invertebrates, 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:
None
Analytical monitoring:
no
Details on sampling:
not applicable
Vehicle:
no
Details on test solutions:
not applicable
Test organisms (species):
Daphnia sp.
Details on test organisms:
not applicable
Test type:
other: calculation method
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Remarks on exposure duration:
48h-EL50 (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:
48 h
Dose descriptor:
EL50
Effect conc.:
11 mg/L
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: Based on typical composition of carrot seeds oil rich in carotol
Key result
Duration:
48 h
Dose descriptor:
EL50
Effect conc.:
11 mg/L
Conc. based on:
test mat.
Basis for effect:
mobility
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 48-hour EL50 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 EL50.

 

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

5.8

3.2

constituent 2

0.75

0.54

constituent 3

0.35

0.32

constituent 4

0.0029

0.0033

constituent 5

0.0022

0.0012

constituent 6

0.0029

0.0068

constituent 7

0.16

0.038

constituent 8

0.15

0.086

constituent 9

0.12

0.064

constituent 10

0.10

0.037

constituent 11

0.0011

-

constituent 12

0.00039

0.00036

constituent 13

0.10

0.067

constituent 14

0.088

0.43

constituent 15

0.094

0.11

constituent 16

-

0.95

constituent 17

-

0.82

constituent 18

-

0.0015

constituent 19

-

0.00046

constituent 20

-

0.070

 

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: 48h-EL50 = 11 mg/L
- Carrot seeds oil rich in geraniol: 48h-EL50 = 11 mg/L
Executive summary:

CARROT SEEDS OIL is a Natural Complex Substance (UVCB) with a well-defined composition. Its acute toxicity to aquatic invertebrates has been investigated using an in-house calculation method that replaces an OECD 202 study and guideline for Testing of Chemicals No. 23 (i.e. WAF conditions).

The typical composition of both qualities of the substance 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 analysable fraction of a WAF study. In the calculation the second step is to remove this non-bioavailable fraction. 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.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 EC50s of each constituent were predicted using the iSafeRat QSAR model (and QPRF as well as the QMRF are provided). An additivity approach (based on Chemical Activity of each constituent) is used in order to calculate the Effective Loading rate of the WAF.

The 48-h EL50 was predicted to be 11 mg test material/L for both qualities.

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: 48h-EL50 = 11 mg/L

- Carrot seeds oil rich in geraniol: 48h-EL50 = 11 mg/L

For the registered substance, the key 48h-EL50 value selected for that endpoint is therefore 11 mg/L.

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
11 mg/L

Additional information

For that endpoint, one reliable study was available: an in-house calculation method that replaces an OECD 202 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 analysable fraction of a WAF study. In the calculation the second step is to remove this non-bioavailable fraction. 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.

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 EC50s of each constituent were predicted using the iSafeRat QSAR model (see table below) and the QMRF/QPRF have been attached to the dossier:

constituents

48h-EC50(mg.L-1) used

constituent 1

4.5

constituent 2

0.80

constituent 3

0.39

constituent 4

> solubility limit

constituent 5

> solubility limit

constituent 6

> solubility limit

constituent 7

1.2

constituent 8

56

constituent 9

0.44

constituent 10

0.73

constituent 11

> solubility limit

constituent 12

> solubility limit

constituent 13

0.62

constituent 14

0.75

constituent 15

0.78

constituent 16

24

constituent 17

2.6

constituent 18

> solubility limit

constituent 19

> solubility limit

constituent 20

60

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 results below are the anticipated acute toxicity values during a 48-hour EL50 study on daphnids based on the two compositions of CARROT SEEDS OIL. The 48-hour EL50 are calculated as follows:

 

Composition

Time (h)

EL50(mg test item.L-1)

Carrot Seeds oil
(rich in carotol)

48

11

Carrot Seeds oil
(rich in geraniol)

48

11

As it can be seen, both qualities are expected to have the same 48h-EL50. As a conclusion for that endpoint, the 48h-EL50 is selected as the key value for the registered substance.

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 considered as acceptable and can be used for that endpoint.