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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)
Adequacy of study:
key study
Study period:
2018-02-22 to 2018-04-24
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
accepted calculation method
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 acute toxicity to daphnia was determined using a validated QSAR model 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 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. 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:
not specified
Specific details on test material used for the study:
Not applicable
Analytical monitoring:
not required
Details on sampling:
Not applicable
Vehicle:
no
Details on test solutions:
Not applicable.
Test organisms (species):
Daphnia magna
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.:
10 mg/L
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: 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 48-hour EL50 the expected concentrations of each constituent in the mixture (based on thermodynamiccalculation) are as follows:

constituents

concentration in the WAF (mg.L-1)

constituent 1

7.0

constituent 2

0.014

constituent 3

0.010

constituent 4

0.0055

constituent 5

0.0035

constituent 6

0.0019

Validity criteria fulfilled:
yes
Conclusions:
The calculated 48h-EL50 of Patchouli EO Fraction Patchoulol Rich for the typical composition is of 10mg/L.
Executive summary:

Patchouli EO Fraction Patchoulol Rich 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 composition 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 are already known from literature or predicted using the iSafeRat QSAR model. An additivity approach (based on Chemical Activity of each constituent) is used in order to calculate the Effective Loading rate of the WAF.

The 48h-EL50 was 10 mg test item/L for the typical composition of Patchouli EO Fraction Patchoulol Rich.

 

Results Synopsis

Test Type: Calculation method

48h-EL50: 10 mg test material/L based on the typical composition

Description of key information

Based on a calculation method, the following toxicity value has been found for the registered substance:

- 48h-EL50 = 10 mg test item/L

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
10 mg/L

Additional information

For that endpoint, one study with the registered substance 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 composition of the substance has been investigated. 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 already known from litterature or were predicted using the iSafeRat QSAR model.

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 value anticipated during a 48-hourEL50 study on daphnids based onthe WAF method. The 48-hour EL50 is calculated as follows:

 

Composition

Time (h)

EL50(mg test item.L-1)

typical

48

10

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.