Imidazolium compounds, 2-C4-8-alkyl-1-(2-carboxyethyl)-4,5-dihydro-3-(hydroxyethyl), hydroxides, sodium salts

Short-term toxicity to aquatic invertebrates

Administrative data

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

4 - 13 October 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Report date:

2018

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Version / remarks:

13 April 2004

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Version / remarks:

30 May 2008

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Imidazolium compounds, 2-C4-8-alkyl-1-(2-carboxyethyl)-4,5-dihydro-3-(hydroxyethyl), hydroxides, sodium salts

EC Number:

275-085-2

EC Name:

Imidazolium compounds, 2-C4-8-alkyl-1-(2-carboxyethyl)-4,5-dihydro-3-(hydroxyethyl), hydroxides, sodium salts

Cas Number:

70983-43-6

Molecular formula:

see structural formula below, for n=4 C13H24N2O3 HO.Na

IUPAC Name:

Imidazolium compounds, 2-C4-8-alkyl-1-(2-carboxyethyl)-4,5-dihydro-3-(hydroxyethyl), hydroxides, sodium salts

Test material form:

liquid

Remarks:

oily liquid

Details on test material:

Batch No.: 54542L16
Storage at room temperature, protected from light.

Sampling and analysis

Analytical monitoring:

yes

Test solutions

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION

The following test vessels were set up:
- Test solution (Tn); containing Daphnia medium with test item (four replicates per concentration with five Daphnia each)
- Blank control (Bn); containing pure Daphnia medium (four replicates per concentration with five Daphnia each)
- Since the test item is soluble, the test solutions were prepared by respective dilutions of a stock solution (test item dissolved in Daphnia medium) with aerated Daphnia medium. The resulting solutions were used as test solutions in the toxicity test.
Pure Daphnia medium served as blank controls.
- O2 concentration and pH were measured in the test medium for each concentration including the blank control. If the O2 concentration was too low (>5.0 mg/l required) the media was aerated by stirring. Afterwards, the media were filled into the test vessels (50 ml per vessel).
- Daphnia, aged less than 24 h and already acclimatized to the Daphnia medium, were then introduced into the test media, and the vessels were covered with a glass plate. The Daphnia were not fed during the test and the test vessels were not aerated.
- Evidence of undissolved material: Not relevant. Due to high solubility (>= 368 g/l at pH 10 and at 22°C), as determined in the test OECD 105 (ACH study no. A17-00691), the test solutions were prepared by dilution of a stock solution

Test organisms

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISMS
- Test organism: Daphnia magna (Straus, 1820), derived from a healthy stock and not first brood progeny
- Breeding: Parental and young Daphnia held in 4 l glass aquaria (3 l medium) at 20±2°C
- Illumination: 16 h per day
- Medium: Continuously aerated Elendt M4 medium prepared with ultra-pure water (conductivity <1.5 µS/cm)
- Feed: Suspension of Desmodesmus subspicatus in Elendt M4 medium with an optical density OD680 of about 15 units

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Test conditions

Hardness:

not reported

Test temperature:

18–22°C, controlled at ±1 °C

pH:

6.7 to 7.5

Dissolved oxygen:

The minimum dissolved oxygen concentration in the controls and the test vessels at the end of each 24 h-period was >=6.8 mg O2/l (required >=3 mg O2/l).

Salinity:

not reported

Conductivity:

661 to 666 µS cm-1

Nominal and measured concentrations:

The concentrations of Imidazolium compounds, 2-C4-8-alkyl-1-(2-carboxyethyl)-4,5-dihydro-3-(hydroxyethyl), hydroxides, sodium salts in the test medium were determined by HPLC analysis at the beginning and after 24 and 48 h of exposure. These analyses revealed that the concentrations of the test item were stable over the whole 48 h test period. The measured concentrations of the test item at the beginning of the test were 116, 57.4, 28.3, 14.3 and 7.56 mg/l; and 121, 60.5, 29.5, 14.8 and 7.91 mg/l (i.e. respectively 104, 105, 104, 103 and 105 % of the initial value) after 48 h of exposure. The measured concentrations of the two highest concentrations and of the lowest concentration were slightly out of the 80-120% range of the nominal concentration (e.g. 115-127%).

Details on test conditions:

TEST SYSTEM
- Test vessel: 100 ml beakers, all-glass, with 50 ml of test medium,covered with a glass plate to avoid evaporation and contamination of the test solutions with dust
- Test medium: Elendt M4 medium; prepared with ultra-pure water (conductivity <1.5 µS/cm)
- Number of Daphnia: 20 individuals per test concentration and for the blank, divided in 4 groups of 5 individuals
- Age: Less than 24 h
- Light: 16 h photoperiod a day, supplied by overhead white fluorescent tubes
- Temperature: 18–22 °C, controlled at ±1 °C
- pH: 6 to 9. The pH should normally not vary by more than 1.5 units in one test.
- Feed: The Daphnia are not fed during the test
- Aeration: The test vessels were not aerated during the test.
- Test type: static exposure conditions
- Test duration: 48 h

RANGE-FINDING STUDY
Prior to the definitive test a non-GLP range finding test with nominal concentrations of 1, 10 and 100 mg/l of Imidazolium compounds, 2-C4-8-alkyl-1-(2-carboxyethyl)-4,5-dihydro-3-(hydroxyethyl), hydroxides, sodium salts was performed.
The HPLC determinations indicate that the test item concentrations are stable. Static conditions were therefore applied in the definitive test.

EFFECT PARAMETERS MEASURED
Observed immobility (inability to swim) of the daphnids: Observations of immobile Daphnia were made after 24 and 48 h of exposure. Any abnormal behaviour or appearance was reported.

Reference substance (positive control):

yes

Remarks:

Acute reference test with potassium dichromate conducted twice a year

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

48 h

Dose descriptor:

EC10

Effect conc.:

44 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Effect concentrations 2

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

84.2 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Effect concentrations 3

Key result

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

29.1 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Effect concentrations 4

Duration:

24 h

Dose descriptor:

EC10

Effect conc.:

75.1 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Effect concentrations 5

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

160 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Effect concentrations 6

Duration:

24 h

Dose descriptor:

NOEC

Effect conc.:

58.7 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

After 24 h, following immobilization rates were observed: 30% at 100 mg/l. No significant effects (<=10% immobilization) were observed at 50.0, 25.0, 12.5 and 6.25 mg/l or in the blank controls.
Based on these effects and the measured concentrations of the test item, the 24h-EC50 of Imidazolium compounds, 2-C4-8-alkyl-1-(2-carboxyethyl)-4,5-dihydro-3-(hydroxyethyl), hydroxides, sodium salts to Daphnia magna was calculated to be 160 mg/l (95% confidence limits: 115–1433 mg/l).
The low effect concentration EC10 after 24h was calculated to be 75.1 mg/l (95% confidence limits: 23.8–100 mg/l).
The no observed effect concentration (NOEC) after 24h was determined to be 58.7 mg/l.
After 48 h, following immobilization rates were observed: 80% at 100 mg/l and 15% at 50.0 mg/l. No significant effects (<=10% immobilization) were observed at 25.0, 12.5 and 6.25 mg/l or in the blank controls.
Based on these effects and the measured concentrations of the test item, the 48h-EC50 of Imidazolium compounds, 2-C4-8-alkyl-1-(2-carboxyethyl)-4,5-dihydro-3-(hydroxyethyl), hydroxides, sodium salts to Daphnia magna was calculated to be 84.2 mg/l (95% confidence limits: 68.3–109 mg/l).
The low effect concentration EC10 after 48h was calculated to be 44.0 mg/l (95% confidence limits: 26.5–56.1 mg/l).
The no observed effect concentration (NOEC) after 48h was determined to be 29.1 mg/l.

Results with reference substance (positive control):

Acute ref. test with K2Cr2O7 conducted twice a year. The EC50 value for the control of sensitivity for 24 h of exposure with K2Cr2O7 was estimated to be 0.89 mg/l (29.6.2016), which lies within the recomm. range of 0.6–2.1 mg/l acc. to OECD Guideline 202.

Reported statistics and error estimates:

The effective concentrations ECx were assessed based on the geometric mean of the measured concentrations.
Statistical analysis was performed with respect to ECx values and their 95% confidence intervals whenever possible.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Remarks:

All validity criteria i.e. immobilization in the controls <=10% and O2 concentrations at the end of the test >=3 mg/L were fulfilled.

Conclusions:

The acute toxicity of the substance Imidazolium compounds, 2-C4-8-alkyl-1-(2-carboxyethyl)-4,5-dihydro-3-(hydroxyethyl), hydroxides, sodium salts (CAS no. 70983-43-6) to Daphnia magna were investigated according to test guideline OECD 202, under static exposure conditions over a period of 48 h. Based on these effects and the measured concentrations of the test item, the 24h-EC50 of Imidazolium compounds, 2-C4-8-alkyl-1-(2-carboxyethyl)-4,5-dihydro-3-(hydroxyethyl), hydroxides, sodium salts to Daphnia magna was calculated to be 160 mg/l (95% confidence limits: 115–1433 mg/l).
The low effect concentration EC10 after 24h was calculated to be 75.1 mg/l (95% confidence limits: 23.8–100 mg/l).
The no observed effect concentration (NOEC) after 24h was determined to be 58.7 mg/l.
Based on these effects and the measured concentrations of the test item, the 48h-EC50 of Imidazolium compounds, 2-C4-8-alkyl-1-(2-carboxyethyl)-4,5-dihydro-3-(hydroxyethyl), hydroxides, sodium salts to Daphnia magna was calculated to be 84.2 mg/l (95% confidence limits: 68.3–109 mg/l).
The low effect concentration EC10 after 48h was calculated to be 44.0 mg/l (95% confidence limits: 26.5–56.1 mg/l).
The no observed effect concentration (NOEC) after 48h was determined to be 29.1 mg/l.
The results of the test can be considered reliable without restriction.

Executive summary:

The acute toxicity of the substance Imidazolium compounds, 2-C4-8-alkyl-1-(2-carboxyethyl)-4,5-dihydro-3-(hydroxyethyl), hydroxides, sodium salts (CAS no. 70983-43-6) to Daphnia magna were investigated according to test guideline OECD 202, under static exposure conditions over a period of 48 h.

The test item is an oily liquid, has a high solubility (>=368g/l at pH 10 and at 22 °C) and is 100% pure. Consequently, the test media were prepared by respective dilutions of a stock solution.

The investigated nominal concentrationswere 100, 50.0, 25.0, 12.5 and 6.25 mg/l.

20 individuals, divided in 4 groups of 5 individuals, were used per test concentration and for the blank.

The concentrations of the test item in the test medium were determined by HPLC analysis at the beginning and after 24 and 48 h of exposure. These analyses revealed that the concentrations of the test item were stable (e.g 104, 105, 104, 103 and 105% of the initial value) over the whole 48 h test period but were not within 80-120% range of the nominal concentration. Therefore, the effective concentrations ECx were assessed based on the geometric mean of the measured concentrations.

After 24 h, following immobilization rates were observed: 30% at 100 mg/l. No significant effects (=10% immobilization) were observed at 50.0, 25.0, 12.5 and 6.25 mg/l or in the blank controls.

After 48 h, following immobilization rates were observed: 80% at 100 mg/l and 15% at 50.0 mg/. No significant effects (<=10% immobilization) were observed at 25.0, 12.5 and 6.25 mg/l or in the blank controls.

The results of the toxicity of the test item to Daphnia magna after 24 and 48 h of exposure are summarized in the following table, showing EC-values and 95% confidence limits (cl) based on the geometric mean of the measured concentrations:

Parameter, expressed as Measured concentration (mg/l) 24 h of exposure	EC10	EC50	NOEC
Estimate	75.1	160	58.7
Lower 95%-cl	23.8	115	-
Upper 95%-cl	100	1433	-
Parameter, expressed as Measured concentration (mg/l)  48 h of exposure
Estimate	44.0	84.2	29.1
Lower 95%-cl	26.5	68.3	-
Upper 95%-cl	56.1	109	-

cl: confidence limit

The 48 h EC50 value of Imidazolium compounds, 2-C4-8-alkyl-1-(2-carboxyethyl)-4,5-dihydro-3-(hydroxyethyl), hydroxides, sodium salts (CAS no. 70983-43-6) to Daphnia magna was 84.2 mg/l, based on the geometric mean of the measured concentrations.

All validity criteria were fulfilled.