[No public or meaningful name is available]

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

August 04, 2022 to December 02, 2022

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

conducted under GLP conditions

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Version / remarks:

2008

Deviations:

no

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Version / remarks:

2004

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Remarks:

GC-FID

Details on sampling:

In a pre-study the test item was found to be relatively stable over the duration of 48 hours. As such, a static test system was adopted for the study.

Samples were taken and analysed at Time 0 and 48 hours for Control and all test concentration levels.

Vehicle:

no

Details on test solutions:

Based on the results of the stirring experiment and the range-finding test and in agreement with the Sponsor, the following concentrations of GR-87-6331 were selected for the main test: The undiluted equilibrated test medium with a loading rate of 100 mg/L and the dilutions 1:2.2, 1:4.6, 1:10 and 1:22.
Additionally, a control (test water without test item) was tested in parallel.

A static test design in a closed system to avoid losses of the test item by evaporation was chosen since in a pre-experiment, the test item concentration in the test medium was stable during the test period of 48 hours in a closed system.

For each treatment, 20 daphnids were randomly distributed into four replicates of five daphnids each. The volume of test medium provided for each daphnid was 12 mL (60 mL per replicate). Thus, the requirement of the test guidelines for a minimum volume of 2 mL test medium per daphnid was fulfilled.

Dosage:
As the test item is a liquid with low water solubility, the slow-stirring method (to avoid formation of micro-droplets) was applied for preparation of a saturated test item solution. For preparation of the highest concentration of test medium, 218.1 μL of the test item was carefully applied (pipetted) onto the surface of 2310 mL test water. This volume is equivalent to a loading rate of 100 mg/L, considering the density of the test item of 1.059 g/cm3. No auxiliary solvent or emulsifier was used. Thereafter, slow-stirring was applied for 72 hours in a closed vessel at room temperature in the dark.
The undiluted test medium was used as highest test concentration. It was further diluted with test water to prepare the test media with the lower test concentrations applying 5 minutes stirring. Additionally, a control (test water only) was run in parallel.

The test media were prepared just before the start of the test.

All solutions were clear with no evidence of undissolved test item.

The preparation of the test media was based on the OECD Guidance Document No. 23 on Aqueous-Phase Aquatic Toxicity Testing of Difficult Test Chemicals, 2019.

Test organisms (species):

Daphnia magna

Details on test organisms:

The study was performed with young daphnids of the species Daphnia magna Straus.
A clone of this species (originally from the Daphnia Collection of the University of Basel/Switzerland in 2015) is successfully bred at the test facility. The cultivation of the parental daphnids is performed in reconstituted water of the quality identical to the water quality used in the tests (with respect to pH, main ions, and total hardness) and under temperature and light conditions identical to those of the tests (see below).
During breeding, daphnids were generally fed three times a week with an algal suspension of the green algae Desmodesmus subspicatus, supplied by the Collection of Algal Cultures (SAG, Institute for Plant Physiology, University of Göttingen, 37073 Göttingen/Germany) and cultivated at the test facility under standardized conditions or a mixture of this algal suspension and a commercial fish diet (Tetra Min® Hauptfutter, supplied by TETRA-GmbH, 49324 Melle/Germany). At the start of the test, the organisms used in the test were 6-24 hours old and were not first brood progeny.
For evaluation of the quality of the daphnia clone and the experimental conditions, potassium dichromate is tested as a positive control twice a year. The result of the latest positive control test in March 2022 (24-hour EC50: 1.7 mg/L) showed that the sensitivity of the test organisms was within the range given by the OECD 202 Test Guideline (24-hour EC50: 0.60 - 2.1 mg/L).
After the end of the test the organisms in the treatment including the control were disposed.
The test method and the test species are recommended by the international test guidelines.

Test type:

static

Water media type:

freshwater

Remarks:

Reconstituted test water

Limit test:

no

Total exposure duration:

48 h

Hardness:

250 mg/L as CaCO3

Test temperature:

21°C

pH:

7.6 to 7.8

Dissolved oxygen:

8.1 to 8.6 mg O2/L

Nominal and measured concentrations:

Based on the results of the stirring experiment and the range-finding test (see 'Any other information on materials and methods incl. tables' section) and in agreement with the Sponsor, the following concentrations of GR-87-6331 were selected for the main test: The undiluted equilibrated test medium with a loading rate of 100 mg/L and the dilutions 1:2.2, 1:4.6, 1:10 and 1:22.
Additionally, a control (test water without test item) was tested in parallel.

As the test item is a liquid with relatively low water solubility, the slow-stirring method (to avoid formation of micro-droplets) was applied for preparation of a saturated test item solution. For preparation of the highest concentration of test medium, the test item was carefully applied (pipetted) onto the surface of the test water at a loading rate of 100 mg/L. Thereafter slow-stirring was applied for 72 hours in a closed vessel at room temperature in the dark.
After this treatment the lower part of the equilibrated test medium was carefully harvested from the stirring vessel through a tap at the bottom of the vessel. This equilibrated aqueous phase with a loading rate of 100 mg/L, containing dissolved test item only, was used as the highest concentration and was diluted with test water to obtain the dilutions 1:2.2, 1:4.6, 1:10 and 1:22. Additionally, a control (test water without test item) was tested in parallel.

Treatment Analyt. Measd Concn. (mg/L) Geom. Mean (mg/L)
Dilution 0 hour 48 hours
1 : 22 0.0170 0.0165 0.017
1 : 10 0.0347 0.0303 0.032
1 : 4.6 0.0811 0.0670 0.074
1 : 2.2 0.139 0.128 0.13
Undiluted 0.323 0.282 0.30

Details on test conditions:

A 16-hour light to 8-hour dark cycle with a 30-minute transition period was used. Light intensity during the light period was 17.9 to 18.2 μmol m-2 s-1.

Reference substance (positive control):

yes

Remarks:

Potassium Dichromate

Duration:

24 h

Dose descriptor:

EC100

Effect conc.:

0.3 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

0.19 mg/L

95% CI:

>= 0.17 - <= 0.21

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

24 h

Dose descriptor:

EC0

Effect conc.:

0.13 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

24 h

Dose descriptor:

NOEC

Effect conc.:

0.074 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

EC100

Effect conc.:

0.3 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

0.14 mg/L

95% CI:

>= 0.11 - <= 0.16

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

0.074 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: Also corresponding to EC0

Details on results:

The test is considered to be valid, as in the control no daphnids showed immobilization or other signs of disease or stress (e.g., discolouration or unusual behaviour such as trapping at the surface of water). Furthermore, the dissolved oxygen concentration at the end of the test was >=3 mg/L in all test vessels.

Results with reference substance (positive control):

For evaluation of the quality of the daphnia clone and the experimental conditions, potassium dichromate is tested as a positive control twice a year. The result of the latest positive control test in March 2022 (24-hour EC50: 1.7 mg/L) showed that the sensitivity of the test organisms was within the range given by the OECD 202 Test Guideline (24-hour EC50: 0.60 - 2.1 mg/L).

The measured concentrations of the test item in the undiluted test medium and the dilutions 1:2.2, 1:4.6, 1:10 and 1:22 are shown in the table below. The results demonstrate the correct preparation of the test media, i.e. the spacing factor of 2.2 between the different test concentrations was met. At the end of the test, 83 to 97 % of the initially measured values were found.
The mean measured concentrations were calculated as the geometric mean of the concentrations measured at both sampling dates (0 and 48 hours):

Treatment/dilution#	Analytically Measured Concentration of the Test Item [mg/L]		Mean Measured Concentration (Geometric Mean) [mg/L]
	0 Hours	48 Hours
1:22	0.0170	0.0165	0.017
1:10	0.0347	0.0303	0.032
1:4:6	0.0811	0.0670	0.074
1:2:2	0.139	0.128	0.13
Undiluted test medium*	0.323	0.282	0.3

*: Undiluted equilibrated test medium with a loading rate of 100 mg/L.
#: Dilutions of the equilibrated test medium with a loading rate of 100 mg/L.

The biological results are based on the mean measured concentrations and listed in the table below:

Treatment / Dilution#	Mean Measured Concentration mg/L	No. of Daphnids/ Replicate	Immobilized Daphnids after 24 Hours No.	Immobilized Daphnids after 24 Hours %	Immobilized Daphnids after 48 Hours No.	Immobilized Daphnids after 48 Hours %
Control	-	5 5 5 5	0 0 0 0	0	0 0 0 0	0
1:22	0.017	5 5 5 5	0 1 ° 0 0	5	0 1 0 0	5
1:10	0.032	5 5 5 5	0 0 0 1 °	5	0 0 0 1	5
1:4:6	0.074	5 5 5 5	0 0 0 0	0	0 0 0 0	0
1:2:2	0.13	5 5 5 5	0 (5F) 0 (5F) 0 (5F) 0 (5F)	0	3 (2F) 3 (2F) 2 (3F) 1 (4F)	45
Undiluted test medium*	0.30	5 5 5 5	5 5 5 5	100	5 5 5 5	100 $

*: Equilibrated test medium with a loading rate of 100 mg/L.
#: Dilutions of the equilibrated test medium with a loading rate of 100 mg/L.
°: Not considered as a toxic effect of the test item since only 5 % immobility, no dose-response effect and absence of immobility/adverse effects at the dilution 4.6 and absence of immobility at the dilution 1:2.2.
$: All daphnids dead.

Values in parenthesis: number of mobile test animals with adverse effects:
A: daphnids trapped at the water surface
B: daphnids sticking together
C: antennae sticking together
D: daphnids discolored/pale
E: spina stuck
F: reduced swimming activity

No immobilized test organisms were determined in the control throughout the exposure period of 48 hours.

After 24 hours, one daphnid each was immobilized at the two lowest test concentration of mean measured 0.017 and 0.032 mg/L. However, this was not considered as a toxic effect of the test item since only 5 % immobility was observed, not following a dose-response effect based on the absence of immobility at the next two higher test concentrations of mean measured 0.074 and 0.13 mg/L. At the highest mean measured concentrations of 0.30 mg/L, all daphnids were found to be immobile.
The 24-hour EC50 of the test item was calculated to be 0.19 mg/L with 95 % confidence limits of 0.17 and 0.21 mg/L. The 24-hour EC0 and NOEC were at the mean measured concentration of 0.13 and 0.074 mg/L, respectively. The 24-hour EC100 was determined to be 0.30 mg/L (mean measured).

After 48 hours of exposure, no additional immobilized test organisms were found in the three lowest test concentrations up to and including the mean measured concentration of 0.074 mg/L. At the next higher test concentration of 0.13 mg/L, 9 test organisms were found to be immobile, corresponding to an immobilization rate of 45 % (in addition, all surviving daphnids were found to have reduced swimming activity). At the mean measured concentrations of 0.30 mg/L, all daphnids were immobile (i.e. dead) after 48 hours exposure time.

The 48-hour EC50 of the test item was calculated to be 0.14 mg/L with 9 5% confidence limits of 0.11 and 0.16 mg/L. The 48-hour EC0 and NOEC were at the mean measured concentration of 0.074 mg/L. The 48-hour EC100 was determined to be 0.30 mg/L (mean measured).

No remarkable observations were made concerning the appearance of the test media. All test media remained clear solutions throughout the test.

At the beginning and end of the test period, the dissolved oxygen concentrations in the test media and control were at least 8.1 mg/L, the pH value of the test media was in the range of 7.6 to 7.8, and the water temperature during the test was kept at of 21 °C.

Validity criteria fulfilled:

yes

Conclusions:

The 48-hour EC50 of the test item was calculated to be 0.14 mg/L with 9 5% confidence limits of 0.11 and 0.16 mg/L. The 48-hour EC0 and NOEC were at the mean measured concentration of 0.074 mg/L. The 48-hour EC100 was determined to be 0.30 mg/L (mean measured).

Executive summary:

The acute toxicity of the test item to Daphnia magna was determined in a 48-hour static test in a closed system according to the OECD Guideline for Testing of Chemicals, No. 202 (2004) and the Commission Regulation (EC) No. 440/2008, Part C.2.

As the test item is thought to be a volatile substance, the test was performed using glass tubes completely filled (without headspace) with test medium that were tightly sealed with glass stoppers to avoid losses of test item by evaporation (closed system). A static test design was used.

As the test item is a liquid with relatively low water solubility, the slow-stirring method (to avoid formation of micro-droplets) was applied for preparation of a saturated test item solution. For preparation of the highest concentration of test medium, the test item was carefully applied (pipetted) onto the surface of the test water at a loading rate of 100 mg/L. Thereafter slow-stirring was applied for 72 hours in a closed vessel at room temperature in the dark.
After this treatment the lower part of the equilibrated test medium was carefully harvested from the stirring vessel through a tap at the bottom of the vessel. This equilibrated aqueous phase with a loading rate of 100 mg/L, containing dissolved test item only, was used as the highest concentration and was diluted with test water to obtain the dilutions 1:2.2, 1:4.6, 1:10 and 1:22. Additionally, a control (test water without test item) was tested in parallel.
The preparation of the test media was based on the OECD Guidance Document No. 23 on Aqueous-Phase Aquatic Toxicity Testing of Difficult Test Chemicals, 2019.

The measured concentrations of the test item in the undiluted test medium and the dilutions 1:2.2, 1:4.6, 1:10 and 1:22 are shown in the table below. The results demonstrate the correct preparation of the test media, i.e. the spacing factor of 2.2 between the different test concentrations was met. At the end of the test 83 to 97 % of the initially measured values were found. The mean measured concentrations were calculated as the geometric mean of the concentrations measured at both sampling dates (0 and 48 hours).

Treatment/dilution#	Analytically Measured Concentration of the Test Item [mg/L]		Mean Measured Concentration (Geometric Mean) [mg/L]
	0 Hours	48 Hours
1:22	0.0170	0.0165	0.017
1:10	0.0347	0.0303	0.032
1:4:6	0.0811	0.0670	0.074
1:2:2	0.139	0.128	0.13
Undiluted test medium*	0.323	0.282	0.3

*: Undiluted equilibrated test medium with a loading rate of 100 mg/L.
#: Dilutions of the equilibrated test medium with a loading rate of 100 mg/L.

The biological end-point results were based on the mean measured concentrations.
A clear dose-response effect was observed over the exposure period of 48 hours at the highest test concentrations. At the two lowest mean measured concentrations of 0.017 and 0.032 mg/L one daphnid each, i.e., 5 % of the daphnids were found immobile after 24 hours of exposure. At the next higher concentration of mean measured 0.074 mg/L, no toxic effect was observed until test end. At the two highest test concentrations of mean measured 0.13 and 0.30 mg/L, 45 % and 100 % of the daphnids were found to be immobile after 48 hours, respectively.

ECx Values Immobility	Based on Mean Measured Concentrations of the Test Item [mg/L]
24-hour EC50 (95 % Confidence Limits)	0.19 (0.17-0.21)
24-hour EC0	0.13
24-hour NOEC	0.074
24-hour EC100	0.3
48-hour EC50 (95 % Confidence Limits)	0.14 (0.11-0.16)
48-hour EC0 and 48-hour NOEC	0.074
48-hour EC100	0.3

Validity criteria:
The test is considered to be valid, as in the control no daphnids showed immobilization or other signs of disease or stress (e.g., discoloration, surface trapping, reduced swimming etc.). Furthermore, the dissolved oxygen concentration at the end of the test was >=3 mg/L in all test vessels.

Description of key information

The acute toxicity of the test item to Daphnia magna was determined in a 48-hour static test in a closed system according to the OECD Guideline for Testing of Chemicals, No. 202 (2004) and the Commission Regulation (EC) No. 440/2008, Part C.2.

As the test item is thought to be a volatile substance, the test was performed using glass tubes completely filled (without headspace) with test medium that were tightly sealed with glass stoppers to avoid losses of test item by evaporation (closed system). A static test design was used.

As the test item is a liquid with relatively low water solubility, the slow-stirring method (to avoid formation of micro-droplets) was applied for preparation of a saturated test item solution. For preparation of the highest concentration of test medium, the test item was carefully applied (pipetted) onto the surface of the test water at a loading rate of 100 mg/L. Thereafter slow-stirring was applied for 72 hours in a closed vessel at room temperature in the dark.
After this treatment the lower part of the equilibrated test medium was carefully harvested from the stirring vessel through a tap at the bottom of the vessel. This equilibrated aqueous phase with a loading rate of 100 mg/L, containing dissolved test item only, was used as the highest concentration and was diluted with test water to obtain the dilutions 1:2.2, 1:4.6, 1:10 and 1:22. Additionally, a control (test water without test item) was tested in parallel.
The preparation of the test media was based on the OECD Guidance Document No. 23 on Aqueous-Phase Aquatic Toxicity Testing of Difficult Test Chemicals, 2019.

The measured concentrations of the test item in the undiluted test medium and the dilutions 1:2.2, 1:4.6, 1:10 and 1:22 are shown in the table below. The results demonstrate the correct preparation of the test media, i.e. the spacing factor of 2.2 between the different test concentrations was met. At the end of the test 83 to 97 % of the initially measured values were found. The mean measured concentrations were calculated as the geometric mean of the concentrations measured at both sampling dates (0 and 48 hours).

Treatment/dilution#	Analytically Measured Concentration of the Test Item [mg/L]		Mean Measured Concentration (Geometric Mean) [mg/L]
	0 Hours	48 Hours
1:22	0.0170	0.0165	0.017
1:10	0.0347	0.0303	0.032
1:4:6	0.0811	0.0670	0.074
1:2:2	0.139	0.128	0.13
Undiluted test medium*	0.323	0.282	0.3

*: Undiluted equilibrated test medium with a loading rate of 100 mg/L.
#: Dilutions of the equilibrated test medium with a loading rate of 100 mg/L.

 

The biological end-point results were based on the mean measured concentrations.
A clear dose-response effect was observed over the exposure period of 48 hours at the highest test concentrations. At the two lowest mean measured concentrations of 0.017 and 0.032 mg/L one daphnid each, i.e., 5 % of the daphnids were found immobile after 24 hours of exposure. At the next higher concentration of mean measured 0.074 mg/L, no toxic effect was observed until test end. At the two highest test concentrations of mean measured 0.13 and 0.30 mg/L, 45 % and 100 % of the daphnids were found to be immobile after 48 hours, respectively.

ECx Values Immobility	Based on Mean Measured Concentrations of the Test Item [mg/L]
24-hour EC50 (95 % Confidence Limits)	0.19 (0.17-0.21)
24-hour EC0	0.13
24-hour NOEC	0.074
24-hour EC100	0.3
48-hour EC50 (95 % Confidence Limits)	0.14 (0.11-0.16)
48-hour EC0 and 48-hour NOEC	0.074
48-hour EC100	0.3

 

Validity criteria:
The test is considered to be valid, as in the control no daphnids showed immobilization or other signs of disease or stress (e.g., discoloration, surface trapping, reduced swimming etc.). Furthermore, the dissolved oxygen concentration at the end of the test was >=3 mg/L in all test vessels.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Dose descriptor:

EC50

Effect concentration:

0.14 mg/L

Additional information

According to the EU CLP regulation (No 1272/2008 and its adaption 286/2011), the substance needs to be classified as Hazardous to the Aquatic Environment Acute 1 and Chronic 1 classifications (Aquatox test results below 1 mg/L). No M factor needs to be applied.