Artemisia herba-alba, ext.

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

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:

2017-09-11 to 2017-09-15

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

accepted calculation method

Remarks:

Calculation method is used; calculation method applicable for that endpoint.

Justification for type of information:

QMRF and QPRF are attached in the part "attached background material"

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 estimated 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:

None

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

Duration:

72 h

Dose descriptor:

EL50

Remarks:

effective loading rate of WAF

Effect conc.:

64 mg/L

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other:

Remarks:

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

constituents	concentration in the WAF (mg.L^-1)
α/β-thujone	52
camphor	4.4
camphene	0.29
sabinene	0.23

Validity criteria fulfilled:

yes

Conclusions:

72h-ErL50 for the typical composition of Artemisia herba-alba oil (thuyone type) is 64 mg test item/L.

Executive summary:

The registered substance is a Natural Complex Substance (UVCB) with a well-defined composition. Its acute toxicity to aquatic algae 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 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 are estimated 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.

Using this approach, the 72-h ErL50 was 64 mg test material/L. ErL50 was based on growth rate.

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.

 

Results Synopsis

Test Type: Calculation method

ErL50: 64 mg test material/L for the typical composition

Description of key information

72h-ErL50 for typical composition of the registered substance is 64 mg test item/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.

Key value for chemical safety assessment

EC50 for freshwater algae:

64 mg/L

Additional information

The toxicity to aquatic algae of the UVCB Artemisia herba-alba oil (thuyone type) has been investigated using a reliable 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 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 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 were predicted using the iSafeRat QSAR model and the QMRF/QPRF have been attached to the dossier:

constituents	48h-EC50 (mg.L^-1) used
α/β-thujone	24
camphor	24
camphene	0.64
sabinene	0.66

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

Based on the results of this study, the registered substance would not be acutely toxic to aquatic organisms in accordance with the classification of the CLP.

This toxicity study is acceptable and can be used for that endpoint.