(2-methyl-5-propan-2-ylcyclopentyl) propanoate

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

disregarded due to major methodological deficiencies

Study period:

From June 23, 2010 to September 10, 2010

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

significant methodological deficiencies

Remarks:

This study was performed according to OECD Guideline 202 with GLP certificate. All validity criteria were fulfilled. However, this study is not reliable due to the high concentration of solvent (acetone) used in combination with the test substance. Because of the potential for interaction with the test chemical resulting in an altered response in the test, solvent use should be restricted to situations where no other acceptable method of test solution preparation is available. The use of solvent is not necessary for aquatic toxicity testing except under exceptional circumstances. Furthermore, solvents are generally not appropriate for testing multiconstituent substances, such as this test substance (which is a mixture of isomers), as it may alter the relative composition of the consituents by changing the solubility of one or more components and thereby the toxicity. Furthermore, the concentration/quantity of solvent used in the treatment solutions was 5 mL/L, corresponding to 3.95 g/L (with a density of 0.79), which is 50 times higher than the recommended maximum level of solvent (below 0.1 mL/L; OECD No. 23) and represents almost half of the EC50 of acetone (which was reported in the ECHA disseminated dossier at 8.8 g/L). Acetone is suspected to have affected the definitive results. Some solvent/substance interactions may have occurred in this study with this high concentration of acetone.

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Version / remarks:

April 2004

Deviations:

yes

Remarks:

Solvent was used, which is not the best method existing at the time being.

GLP compliance:

yes (incl. QA statement)

Remarks:

Date of inspection 23-24 July 2009 / GLP certificate signed on 01 June 2010

Specific details on test material used for the study:

- Appearance: Colourless translucent liquid
- Storage condition of test material: Room temperature protected from direct sun light

Analytical monitoring:

yes

Details on sampling:

The test item concentrations were measured at test initiation and at the end of test.
Duplicate set of test tubes were prepared. The first one was used for the quantification of the test substance at test initiation. The second one was kept under the same environmental conditions as the test tubes and was used for the quantification of the test substance at the end of test. The test substance was quantified according to a previously validated method.

Vehicle:

yes

Remarks:

acetone

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: The treatment solutions were prepared in acetone. Information concerning the preparation of the test item treatments is given in Table 6.1.1/1 in "Any other information on materials and methods incl. tables".
- Controls: water controls (the control tubes made with 10 mL of reconstitued water) and solvent control (10 mL of reconstitued water and 50 µL of acetone).
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): acetone
- Concentration of vehicle in test medium (stock solution and final test solution(s) or suspension(s) including control(s)): 5 mL/L
- Evidence of undissolved material (e.g. precipitate, surface film, etc.): not reported

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Strain/clone: Daphnia magna
- Source: received from a commercial breeder. These organisms were regularly sub-cultured at the Phytosafe site and fed with living cells of the green algae.
- Age of parental stock (mean and range, SD): Young daphnids produced within 24 hours were used for the tests.
- Feeding during test: Daphnids were not fed during the exposure period.

Test type:

static

Water media type:

freshwater

Remarks:

M4 mineral medium

Limit test:

no

Total exposure duration:

48 h

Hardness:

64.8 mg/L of NaHCO3 in the reconstituted water.

Test temperature:

The temperature conditions were checked to be 20°C kept constant at +/- 1°C for both the range-finding test and the definitive test.

pH:

7.05 to 7.66.

Dissolved oxygen:

5.9 to 7.5 mg dissolved O2/L.
The dissolved oxygen concentration exceeded 75% in the control and test tubes and was therefore greater than 6.75 mg/L on the basis of 9 mg/L as the saturation value

Salinity:

Not applicable

Nominal and measured concentrations:

- Nominal treatment concentrations: 0.92, 1.56, 2.64, 4.47 and 7.58 mg/L.
- Measured concentrations: See table 6.1.1/2 in "Any other information on results incl. tables".
The treatment concentrations were satisfactorily maintained within 80-120% of the nominal values

Details on test conditions:

TEST SYSTEM
- Test vessel: 15 mL capacity glass tubes
- Type (delete if not applicable): The tubes were maintained at dark in a climatic chamber, and were tightly capped during the exposure period so as to avoid volatilization of the test item. The controls were conducted accordingly.
- Material, size, headspace, fill volume: filled with 10 mL of M4 mineral medium
- No. of organisms per vessel: 5 daphnids per replicate unit
- No. of vessels per concentration (replicates): 4 replicate units
- No. of vessels per control (replicates): 4 replicate units
- No. of vessels per vehicle control (replicates): 4 replicate units

TEST MEDIUM / WATER PARAMETERS
The M4 mineral medium was freshly reconstituted from analytical water and liquots sampls of mineral stock solutions.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Each test tube was checked for immobilized daphnids 24 and 48 hours after the start of the test. Any abnormal behavior or appearance, if any, was reported.

VEHICLE CONTROL PERFORMED: yes

RANGE-FINDING STUDY
- Test concentrations: 0.01 - 0.10 - 1.0 - 10.1 and 100.6 mg/L
- Results used to determine the conditions for the definitive study: The mobility of the daphnids was not affected for test item treatment up to and including 1 mg/L. 20% of the daphnids were immobilized after 48 h of testing at 10 mg/L, and 100% at 100 mg/L.A first definitive test was performed for test item treatments between aproximately 10 and 100 mg/L. Surprisingly, most of the daphnids were immobilized after 24 h of testing and the test was not further continued. The second definitive test was performed for test item treatments between 0.9 and 7.6 mg/L.

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

1.99 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: based on analytically confirmed nominal concentrations // 95% confidence interval : 1.48 - 2.67 mg/L

Duration:

48 h

Dose descriptor:

other: The highest tested concentration without observed effect

Effect conc.:

0.92 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: based on analytically confirmed nominal concentrations

Details on results:

See table 6.1.3/3 in "Any other information on results incl. tables".

Results with reference substance (positive control):

- Results with reference substance valid? Yes
- ECx: 24h-EC50 for Potassium dichromate fell within 0.6 - 1.7 mg/L. Calculation gave 1.8 mg/L as the measured value.

Table 6.1.3/2 : Measured concentrations for the test substance (mg/L) throughout the test period

Aqueous nominal concentration	Measured concentration		Mean % of the nominal value
	Replicate 1	Replicate 2
Test initiation
0.92 mg/L 1.56 mg/L 2.64 mg/L 4.47 mg/L 7.58 mg/L	1.02 mg/L 1.85 mg/L 2.86 mg/L 5.15 mg/L 8.37 mg/L	- - - - -	111.0 % 119.1 % 108.5 % 115.2 % 110.4 %
End of test
0.92 mg/L 1.56 mg/L 2.64 mg/L 4.47 mg/L 7.58 mg/L	0.75 mg/L 1.60 mg/L 2.17 mg/L 4.45 mg/L 7.10 mg/L	0.78 mg/L 1.55 mg/L 2.07 mg/L 4.54 mg/L 7.45 mg/L	87.0 % 101.2 % 80.5 % 100.6 % 96.0 %

Table 6.1.3/3 : Definitive test - % immobilized daphnids for the controls and the test item treatments

		% immobilization after 24 hours				% immobilization after 48 hours
		Rep 1	Rep 2	Rep 3	Rep 4	Rep 1	Rep 2	Rep 3	Rep 4
Water control		0	0	0	0	0	0	0	0
Solvent control		0	20	0	0	0	20	0	0
Test substance	0.92 mg/L 1.56 mg/L 2.64 mg/L 4.47 mg/L 7.58 mg/L	0 0 60 100 100	20 20 60 100 100	0 20 40 80 100	0 20 20 80 100	0 40 80 100 100	20 40 60 100 100	0 40 60 100 100	0 20 60 100 100

Validity criteria fulfilled:

yes

Remarks:

Immobilization was less than 10% in the controls; the dissolved oxygen concentration exceeded 3 mg/L in the controls and every test item treatment; the 24h-EC50 for potassium dichromate was between 0.6 and 1.7 mg/L.

Conclusions:

The 48h-EC50 value was determined at 1.99 mg/L, with a 95% CI of 1.48 - 2.67 mg/L, based on analytically confirmed nominal concentrations.
Even if all validity criteria were fulfilled, this study is not reliable due to high concentration of solvent used.

Executive summary:

This study was performed according to OECD Guideline 202 with GLP statement, to assess the acute toxicity of the test substance to aquatic invertebrates Daphnia magna.

Following a preliminary range-finding study, 5 daphnids per replicate unit (4 replicate units per treatment) were exposed to the test item (prepared with acetone as solvent) at nominal concentrations of 0.92 - 1.56 - 2.64 - 4.48 and 7.59 mg/L for 48 hours under static test conditions. The number of immobilised Daphnia was recorded after 24 and 48 hours.

Based on analytically confirmed nominal concentrations, the 48 hour EC50 for the test item to Daphnia magna was 1.99 mg/L with 95% confidence limits of 1.48 - 2.67 mg/L. The highest tested concentration without observed effect was 0.92 mg/L.

Even if all validity criteria were fulfilled, this study is not reliable due to high concentration of solvent used. Indeed, a large quantity of acetone was used as solvent in this study. Because of the potential for interaction with the test chemical resulting in an altered response in the test, solvent use should be restricted to situations where no other acceptable method of test solution preparation is available. The use of solvent is not necessary for aquatic toxicity testing except under exceptional circumstances. Furthermore, solvents are generally not appropriate for testing multiconstituent substances, such as this test substance (which is a mixture of isomers), as it may alter the relative composition of the consituents by changing the solubility of one or more components and thereby the toxicity. Furthermore, the concentration/quantity of solvent used in the treatment solutions was 5 mL/L, corresponding to 3.95 g/L (with a density of 0.79), which is 50 times higher than the recommended maximum level of solvent (below 0.1 mL/L; OECD No. 23) and represents almost half of the EC50 of acetone (which was reported in the ECHA disseminated dossier at 8.8 g/L). Acetone is suspected to have affected the definitive results. Some solvent/substance interactions may have occurred in this study with this high concentration of acetone.

Reference 2

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

(Q)SAR

Adequacy of study:

key study

Study period:

29 July 2020

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification

Justification for type of information:

1. SOFTWARE
iSafeRat® – in Silico Algorithms For Environmental Risk And Toxicity

2. MODEL (incl. version number)
iSafeRat® daphEC50 v1.9

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
SMILES: CCC(=O)OC1C(CCC1C(C)C)C
Water Solubility: 15.4 mg/L (KREATiS, 2020)

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
See attached QMRF

5. APPLICABILITY DOMAIN
See attached QPRF

6. ADEQUACY OF THE RESULT
See attached QPRF

Reason / purpose for cross-reference:

reference to other study

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

not applicable

Remarks:

QSAR model

Principles of method if other than guideline:

The ACUTE TOXICITY TO DAPHNIDS (48-HOUR EC50) was determined using iSafeRat® daphEC50, a validated QSAR model for the Mechanism of Action (MechoA) in question (MechoA 2.1, i.e. mono-/poly-esters whose hydrolysis products are narcotics) (Bauer et al., 2018). The purpose of this QSAR model is to accurately predict the acute toxicity to daphnids as would be expected in a
laboratory experiment following the OECD Guideline 202 (OECD, 2004) and EC method C.1 (European Commission, 2008). The QSAR model is based on validated data for a training set of 41 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.

GLP compliance:

no

Remarks:

QSAR model

Specific details on test material used for the study:

- log KOW: 4.3 (Phytosafe, 2011)
- Water Solubility: 15.4 mg/L (KREATiS, 2020)

Analytical monitoring:

no

Details on sampling:

not applicable

Vehicle:

no

Details on test solutions:

not applicable

Test organisms (species):

other: Daphnia magna, Daphnia pulex

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: QSAR model

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Remarks on exposure duration:

Results from a test duration of 48 hours only were used for daphnid species.

Post exposure observation period:

not applicable

Hardness:

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

Salinity:

not applicable

Conductivity:

not applicable

Nominal and measured concentrations:

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

Details on test conditions:

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):

no

Remarks:

QSAR model

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

7.5 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: 95% confidence interval (α = 0.05): 5.9 – 9.5 mg/L

Details on results:

The test item falls within the applicability domain of the model and can therefore be considered as a reliable prediction for ACUTE TOXICITY TO DAPHNIDS (48-HOUR EC50). Therefore, this endpoint value can be considered valid for use in risk assessment and classification and labelling.

Results with reference substance (positive control):

not applicable

Reported statistics and error estimates:

95% confidence interval (α = 0.05): 5.9 – 9.5 mg/L

Applicability Domain

Descriptor domain

The Subcooled Liquid Water Solubility value (15.4 mg/L or -4.111 in log10 (mol/L)) given as the input to the iSafeRat® daphEC50 model falls within the descriptor domain of the model between a Subcooled Liquid Water Solubility of -4.79 to 0.93 in log10 (mol/L).

Structural fragment domain

All chemical groups within the molecular structure are taken into account by the model.

Mechanistic domain

Currently, the iSafeRat® daphEC50 model can reliably predict the aquatic toxicity for chemicals with the following mechanisms of action of toxicity (MechoA):

• non-polar narcosis (MechoA 1.1)

• polar narcosis of alkyl-/alkoxy-phenols (MechoA 1.2)

• polar narcosis of aliphatic amines (MechoA 1.2)

• cationic narcosis of quaternary ammoniums (MechoA 1.3)

• mono-/poly-esters whose hydrolysis products are narcotics (MechoA 2.1)

• hard electrophile reactivity (MechoA 3.1)

• RedOx cycling of primary thiols (MechoA 4.4)

• Proton release of carboxylic acids (MechoA 5.2)

The MechoA of molecules is predicted directly from the structure. The test item as an ester is expected to exert a MechoA 2.1 and can be taken into account by the model (Bauer et al., 2018).

Validity criteria fulfilled:

yes

Conclusions:

The QSAR model used to achieve the study has been fully validated following the OECD recommendations (OECD, 2004). The test item falls within the applicability domain of the model and was therefore reliably predicted for its ACUTE TOXICITY TO DAPHNIDS (48-HOUR EC50). Therefore, this endpoint value can be considered valid for use in risk assessment and classification and labelling.
The ACUTE TOXICITY TO DAPHNIDS (48-HOUR EC50) of the test item was predicted as 7.5 mg/L.
95% confidence interval (α = 0.05): 5.9 – 9.5 mg/L.

Executive summary:

A Quantitative Structure-Activity Relationship (QSAR) model was used to calculate the ACUTE TOXICITY TO DAPHNIDS (48-HOUR EC50) of the test item. This QSAR model has been validated to be compliant with the OECD recommendations for QSAR modeling (OECD, 2004) and 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, 2004), referenced as Method C.2 of Commission Regulation No. 440/2008 (European Commission, 2008). The criterion predicted was the EC50 (Median Effective Concentration), a statistically derived concentration which is expected to cause immobility in 50% of test animals within a period of 48 hours.

The ACUTE TOXICITY TO DAPHNIDS (48-HOUR EC50) was determined using iSafeRat® daphEC50, a validated QSAR model for the Mechanism of Action (MechoA) in question (MechoA 2.1, i.e. mono-/poly-esters whose hydrolysis products are narcotics) (Bauer et al., 2018). The QSAR model is based on validated data for a training set of 41 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.

The test item falls within the applicability domain of the model and was therefore reliably predicted for its ACUTE TOXICITY TO DAPHNIDS (48-HOUR EC50). Therefore, this endpoint value can be considered valid for use in risk assessment and classification and labelling.

The ACUTE TOXICITY TO DAPHNIDS (48-HOUR EC50) of the test item was predicted as 7.5 mg/L.

95% confidence interval (α = 0.05): 5.9 – 9.5 mg/L.

Description of key information

iSafeRat® High-Accuracy-Quantitative Structure-Activity Relationship, KREATIS, 2020 :

48h-EC50 = 7.5 mg/L (95% confidence interval: 5.9 - 9.5 mg/L)

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Dose descriptor:

EC50

Effect concentration:

7.5 mg/L

Additional information

One experimental study and one QSAR prediction are available to assess the short-term toxicity of the registered substance to aquatic invertebrates.

 

The experimental study (Phytosafe, 2010) was considered as not reliable and was disregarded due to major methodological deficiencies. Indeed, a large quantity of acetone was used as solvent in this study. Because of the potential for interaction with the test chemical resulting in an altered response in the test, solvent use should be restricted to situations where no other acceptable method of test solution preparation is available. The use of solvent is not the best method at the time being. Furthermore, solvents are generally not appropriate for multiconstituent substances, like the test substance (which is a mixture of isomers), where the use of the solvent can preferentially dissolve one or more components and thereby affect the toxicity. Then, the concentration/quantity of solvent used in the treatment solutions was 5 mL/L , corresponding to 3.95 g/L (with a density of 0.79), which is 50 times higher than the recommended maximum level of solvent (below 0.1 mL/L; OECD No. 23) and represent almost half of the EC50 of acetone (which was reported in the ECHA disseminated dossier at 8.8 g/L). Therefore, solvent/substance interactions may have occured in this study with this high concentration of acetone and the result cannot be considered fit for use.

 

The QSAR prediction (KREATiS, 2020) was considered as reliable and was used as key data. The QSAR model has been validated to be compliant with the OECD recommendations for QSAR modelling (OECD, 2004) and predicts the endpoint value which would be expected when testing the substance under experimental conditions in a laboratory following OECD Guideline 202. The acute toxicity to daphnids (48h-EC50) was determined using iSafeRat® daphEC50, a validated QSAR model for the Mechanism of Action (MechoA) in question (MechoA 2.1, i.e. mono-/poly-esters whose hydrolysis products are narcotics) (Bauer et al., 2018). The QSAR model is based on validated data for a training set of 41 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. The test item falls within the applicability domain of the model and was therefore reliably predicted for its acute toxicity (48h-EC50) to daphnids. Therefore, this endpoint value can be considered valid for use in risk assessment and classification and labelling.

The 48-h EC50 of the registered substance to daphnids was predicted at 7.5 mg/L (95% CI: 5.9 - 9.5 mg/L).