Essential oil of Matricaria recutita (Asteraceae) obtained from flower tops by steam distillation of European origin

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:

2017-10-24 to 2017-11-14

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

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.:

15 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

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.

Constituents	Concentration in the WAF (mg test item.L^-1)
constituent 1	4.36
constituent 2	0.0161
constituent 3	0.975
constituent 4	0.654
constituent 5	0.228
constituent 6	0.372
constituent 7	0.00100
constituent 8	0.167
constituent 9	0.000759
constituent 10	0.00164

Validity criteria fulfilled:

yes

Conclusions:

The following toxicity value has been found for the registered substance:
- 72h-ErL50 = 15 mg/L

Executive summary:

The registered substance 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 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 15 mg test material/L. ErL50 values was based on growth rate.

Description of key information

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

- 72h-ErL50 = 15 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:

15 mg/L

Additional information

For that endpoint, one study with the registered substance was available. Indeed, the toxicity to aquatic algae of the registered substance 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).

A 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 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	1.4
constituent 2	> solubility limit
constituent 3	6.7
constituent 4	7.1
constituent 5	1.0
constituent 6	102
constituent 7	> solubility limit
constituent 8	3.3
constituent 9	> solubility limit
constituent 10	> solubility limit

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 WAF method. The 72-hour ErL₅₀ is calculated as follows:

Composition	Time (h)	ErL50(mg test item.L^-1)
typical	72	15

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.