Artemisia pallens, ext.

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

mixture rules calculation

Adequacy of study:

key study

Study period:

17 May 2021

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

accepted calculation method

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

yes

Remarks:

(tested according to the Water Accommodated Fraction (WAF) approach, i.e. OECD technical guideline 23)

Principles of method if other than guideline:

The ACUTE TOXICITY TO DAPHNIDS (48-HOUR EL50) was determined using iSafeRat® calculation method adapted for a mixture of compounds with the Mechanism of Action (MechoA) in question (MechoA 1.1, i.e. non-polar narcosis) (Bauer et al., 2018). This method has previously been validated in an internal publication for acute exposure of non-polar narcosis compounds (Bicherel and Thomas, 2014). The algorithm is based on a QSAR model which has been validated to be compliant with the OECD recommandations for QSAR modeling (OECD, 2004b, 2007). The QSAR model is based on validated data for a training set of 58 chemicals derived from 48-hour test on daphnids, 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, this approach is based on validated data derived from 48-hour tests on daphnid, for which the concentrations of the test item had been determined by chemical analyses over the test period.

GLP compliance:

no

Remarks:

(calculation method)

Analytical monitoring:

no

Details on sampling:

not applicable

Vehicle:

no

Details on test solutions:

not applicable

Test organisms (species):

Daphnia magna

Details on test organisms:

No difference in terms of toxic mechanism of action between invertebrate (or indeed other) aquatic species is expected. Any observed differences may be attributed to lifestyle related parameters (e.g. shell closing in molluscs) and relative duration of study versus bodysize rather than to a specific toxic mechanism causing species differences.

Test type:

other: calculation method based on QSAR model predictions

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Remarks on exposure duration:

Only results from a test duration of 48 hours were included in the training set of the model.

Post exposure observation period:

None

Hardness:

The QSAR model is based on data from studies performed at acceptable hardness to ensure control survival.

Test temperature:

The temperatures varied from approximately 20 to 23 °C depending on the species used to construct the algorithm. This small difference is not expected to contribute to the variability of the EC50 values found in experimental data.

pH:

Test results were taken from studies with measured pHs between 6 - 9.

Dissolved oxygen:

The QSAR model is based on data from reliable studies performed at acceptable oxygen concentrations (generally >60%).

Salinity:

Not applicable

Conductivity:

Not applicable

Nominal and measured concentrations:

Studies were used for QSAR model development only where sufficient evidence was presented to determine that the stubstance was stable under test conditions (i.e. maintened within ± 20 % of the nominal) or, if not, the result was based on measured concentrations as geometric mean.

Details on test conditions:

Studies with various test designs were selected for QSAR model development. Preferentially results from semi-static studies were used. However, substances tested using a static design were accepted (preferably accompanied by analytical measurements over the study period). For suspected volatile substances only tests performed in closed vessels were accepted unless accompanying analytical monitoring proved such a design was not necessary.

Reference substance (positive control):

not required

Key result

Duration:

48 h

Dose descriptor:

EL50

Effect conc.:

35 mg/L

Nominal / measured:

nominal

Conc. based on:

other: loading rate of Water Accomodated Fraction (WAF)

Basis for effect:

mobility

Remarks on result:

not determinable

Results with reference substance (positive control):

not applicable

Prior Analysis of the MechoA constituents of the test item.

The calculation method used in this study is based on toxic additivity principle. That means the toxic parts of each constituent are added up. Therefore the constituents considered within the mixture should act with a similar MechoA. The MechoA of the consituents are determined using the methodology described by Bauer et al. (2018) and reported in the Table below.

 

constituents	MechoA	Description
(+)-davanone D	1.1	Non-polar narcosis for all species.
bicyclogermacrene	1.1	Non-polar narcosis for all species.
davana ether	1.1	Non-polar narcosis for all species.
(E) ethyl cinnamate	3.2	Michaël addition with sulfhydryl groups, generating protein and DNA adducts for all species.
(Z) ethyl cinnamate	3.2	Michaël addition with sulfhydryl groups, generating protein and DNA adducts for all species.
guaia-6,9-dien-4 beta-ol	1.1	Non-polar narcosis for all species.
β-selinene	1.1	Non-polar narcosis for all species.
isodavanone	1.1	Non-polar narcosis for all species.
τ-cadinol	1.1	Non-polar narcosis for all species.
(E) methyl cinnamate	3.2	Michaël addition with sulfhydryl groups, generating protein and DNA adducts for all species.
(E) germacrene D	1.1	Non-polar narcosis for all species.
geranyl acetate	1.1	Enzymatic hydrolysis to acid and alcohol/amine + narcosis of the parent compound, for all species.
nordavanone	1.1	Non-polar narcosis for all species.
β-eudesmol	1.1	Non-polar narcosis for all species.
linalool	1.1	Non-polar narcosis for all species.
ledene	1.1	Non-polar narcosis for all species.
methyl jasmonate	2.1	Enzymatic hydrolysis to acid and alcohol/amine + narcosis of the parent compound, for all species.
davanon-2-ol	1.1	Non-polar narcosis for all species.
alloaromadendrene	1.1	Non-polar narcosis for all species.
benzaldehyde	3.1	Hard electrophile reactivity (Schiff-base formation) for all species.
D-limonene	1.1	Non-polar narcosis for all species.

Not all the constituents share the same MechoA (i.e. MechoA 1.1). Some constituents are classified for having another MechoA than MechoA 1.1. However the toxicity of the test item is used in a calculation method based on additivity approach. To apply the calculation method to the test item, all the constituents were considered as following a mechanism of toxic action of non-polar narcosis (i.e. MechoA 1.1) prior to predict their individual aquatic toxicity. Therefore, the global result is considered as reliable with restrictions (mechanism domain).

 

Posterior Analysis of the WAF composition at the toxicity value (E/LL₅₀) for the typical composition.

The Pareto chart within the study report hightlights the importance of each constituent in order to explain the global toxicity of the WAF of the mixture for the toxic loading rate (E/LL₅₀). It indicates the sesquiterpenes (bicyclogermacrene, β-selinene, germacrene D, ledene and alloaromadendrene) explain 45% of the test item toxicity if even if they are expected to not be toxic at their respective water solubility if they are tested as pure. Despite its high concentration in the test item, the toxicity part from (+)-davanone D is only around 10%.

Validity criteria fulfilled:

yes

Conclusions:

The ACUTE TOXICITY TO DAPHNIDS (48-HOUR EL50) of the test item has been determined using the iSafeRat® calculation method for mixtures tested according to the Water Accomodated Fraction (WAF) approach. Each constituents of the test item which have been considered fall within the applicability domain of the model used to determine their individual ACUTE TOXICITY TO DAPHNIDS (48-HOUR EC50). Not all the constituents were identified with the same MechoA (i.e. MechoA 1.1: non-polar narcosis). However the toxicity of the test item is determined by using a calculation method based on additivity approach for MechoA 1.1. To apply the calculation method to the test item, all the constituents were considered as non-polar narcotic prior to predict their individual aquatic toxicity. Therefore, the global result is considered as reliable with restrictions (mechanism domain).

Executive summary:

A calculation method was used to assess the ACUTE TOXICITY TO DAPHNIDS (48-HOUR EL50) of the test item, a Natural Complex Substance, tested according to the Water Accommodated Fraction (WAF) approach. This calculation method predicts the endpoint value which would be expected when testing the substance under experimental conditions in a laboratory following the Guideline for Testing of Chemicals No. 202, "Daphnia sp., Acute Immobilisation Test" (OECD, 2004a), referenced as Method C.2 of Commission Regulation No. 440/2008 (European Commission, 2008) adapted for testing of a mixture using the WAF method. The criterion predicted was the median effective loading rate of the mixture EL₅₀ (Median Effect Loading), a statistically derived loading rate which is expected to cause immobility in 50% of test animals within a period of 48 hours.

 

The ACUTE TOXICITY TO DAPHNIDS (48-HOUR EL50) was determined using iSafeRat® calculation method adapted for a mixture of compounds with the Mechanism of Action (MechoA) in question (MechoA 1.1, i.e. non-polar narcosis) (Bauer et al., 2018). This method has previously been validated in an internal publication for acute exposure of non-polar narcosis compounds (Bicherel and Thomas, 2014). The algorithm is based on a QSAR model which has been validated to be compliant with the OECD recommandations for QSAR modeling (OECD, 2004b, 2007). The QSAR model is based on validated data for a training set of 58 chemicals derived from 48-hour test on daphnids, 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, this approach is based on validated data derived from 48-hour tests on daphnid, for which the concentrations of the test item had been determined by chemical analyses over the test period.

 

Each constituents of the test item which have been considered fall within the applicability domain of the model used to determine their individual ACUTE TOXICITY TO DAPHNIDS (48-HOUR EC50). Not all the constituents were identified with the same MechoA (i.e. MechoA 1.1: non-polar narcosis). However the toxicity of the test item is determined by using a calculation method based on additivity approach for MechoA 1.1. To apply the calculation method to the test item, all the constituents were considered as non-polar narcotic prior to predict their individual aquatic toxicity. Therefore, the global result is considered as reliable with restrictions (mechanism domain).

 

The ACUTE TOXICITY TO DAPHNIDS (48-HOUR EL50) of the test item was predicted as a loading rate of 35 mg/L.

95% confidence interval (α = 0.05): not determined.

Description of key information

iSafeRat® , KREATIS, 2021 :

48h-EL50 = 35 mg/L (95% confidence interval: no determined)

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Dose descriptor:

EC50

Effect concentration:

35 mg/L

Additional information

To assess the short therm toxicity of the registered substance to aquatic invertebrates one QSAR prediction (KREATIS, 2021) is available. 

The ACUTE TOXICITY TO DAPHNIDS (48-HOUR EL50) was determined using iSafeRat® calculation method adapted for a mixture of compounds with the Mechanism of Action (MechoA) in question (MechoA 1.1, i.e. non-polar narcosis) (Bauer et al., 2018). This method has previously been validated in an internal publication for acute exposure of non-polar narcosis compounds (Bicherel and Thomas, 2014). The algorithm is based on a QSAR model which has been validated to be compliant with the OECD recommandations for QSAR modeling (OECD, 2004b, 2007). The QSAR model is based on validated data for a training set of 58 chemicals derived from 48-hour test on daphnids, 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, this approach is based on validated data derived from 48-hour tests on daphnid, for which the concentrations of the test item had been determined by chemical analyses over the test period.

 

Each constituents of the test item which have been considered fall within the applicability domain of the model used to determine their individual TOXICITY TO ALGAE (72-HOUR ErL50 and NOELr). Not all the constituents were identified with the same MechoA (i.e. MechoA 1.1: non-polar narcosis). However the toxicity of the test item is determined by using a calculation method based on additivity approach for MechoA 1.1. To apply the calculation method to the test item, all the constituents were considered as non-polar narcotic prior to predict their individual aquatic toxicity. Therefore, the global result is considered as reliable with restrictions (mechanism domain).

 

The ACUTE TOXICITY TO DAPHNIDS (48-HOUR EL50) of the test item was predicted as a loading rate of 35 mg/L.