2-Propenoic acid, 2-[[1,1,2-trifluoro-2-(1,1,2,2,3,3,3-heptafluoropropoxy)ethyl]thio]ethyl ester

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:

2020-01-15 to 2020-03-04

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Sampling method: Duplicate samples from the freshly prepared test media of all test concentrations and the control were taken at the start of the test and at day 1.
For the determination of the stability of the test item under the test conditions and of the maintenance of the test item concentrations during the test period, duplicate samples from the aged test media of all test concentrations and the control were collected at day 1 (after 24 hours of exposure) and at the end of the test by pouring together the contents of the test beakers of each treatment.
The sample volume was 10 mL.

- Sample storage conditions before analysis: All samples were extracted with dichloromethane immediately after sampling due to the risk of degradation of the test item in the aqueous samples during storage. The organic solvent extracts were stored deep frozen (≤ -20 °C) until analysis.

Vehicle:

no

Details on test solutions:

The test item is not well soluble in test medium. To avoid physical effects of undissolved test item on the daphnids, no concentrations above the solubility limit of the test item in test water was tested.
Therefore, a defined amount of the test item was added directly to the test water (Reconstituted Water Elendt “M4”) for preparing a stock solution of the highest nominal test item concentration and was carefully stirred for 1 hour at room temperature in the dark to dissolve as much of the test item as possible. The highest test item concentration of nominal 100 mg test item/L was prepared by mixing 103.9/104.4 mg test item into 1039/1044 mL test water. After cessation of mixing and a following period (1 hour) of settling to allow phase separation, the aqueous phase, i.e. the water soluble fraction, was drawn off carefully and used as the test medium of the highest nominal test concentration. Adequate volumes of this water soluble fraction were mixed into test water to obtain the desired dilutions of 1:2, 1:4, 1:8 and 1:16.
The test media were prepared just before introduction of the daphnids (= start of the test) and test medium renewal on Day 1.
In the control, test water was used without addition of the test item.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: water flea
- Strain/clone: Straus/clone 5
- Stage and instar at study initiation: Less than 24 hours old
- Source: ibacon’s in-house laboratory culture
- Feeding durig test: no

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

250 mg CaCO3/L

Test temperature:

18.4 - 18.9 °C

pH:

7.7 - 7.8

Dissolved oxygen:

9.3 - 9.6 mg/L

Nominal and measured concentrations:

Nominal concentrations: Water Soluble Fraction (WSF) of nominal 100 mg/L and dilutions of 1:2, 1:4, 1:8 and 1:16 of this WSF,
Measured time weighted average concentrations: 0.0 (control), 45.8, 95.1, 191, 385 and 908 µg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: Glass beakers of 100mL volume covered with a lid
- Volume of solution: 60 mL
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Reconstituted water Elendt “M4”

OTHER TEST CONDITIONS
- Photoperiod: 16/8 hours light/dark cycle
- Light intensity: 540 to 750 lux (measured once during the test)

EFFECT PARAMETERS MEASURED: Number of immobile Daphnia after 24 and 48 hours

RANGE-FINDING STUDY
- Pre-experiments were performed to determine a suitable concentration range and to establish suitable methods to prepare the test solutions.
- Results used to determine the conditions for the definitive study: yes

Reference substance (positive control):

yes

Remarks:

Potassium dichromate, 0, 0.123, 0.25, 0.5, 1.0 and 2.0 mg/L, July 2019

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

706 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: 95 % confidence interval: 600 - 831 μg/L

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

> 908 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: confidence interval not determinable

Details on results:

Biological observation:
After 48 hours of exposure no immobilisation of the test animals was observed in the control and up to and including the test item concentration of 191 μg test item/L. At the concentration of 385 μg test item/L, two daphnids were immobile and 16 daphnids were immobile at the concentration of 908 μg test item/L.

Results with reference substance (positive control):

- Results with reference substance valid: yes
EC50 values with 95 % confidence intervals:
24h EC50: 0.707 mg/L (0.608 – 0.822 mg/L)
48h EC50: 0.542 mg/L (CI: not determinable)

Biological results

Table 1. Influence of the test item on the mobility of Daphnia magna

Time weighted average [µg test item/L]	No. of Daphnia tested	No. of immobilised Daphnia after		% of immobilised Daphnia after		Observations
		24 h	48 h	24 h	48 h	24 h	48 h
Control	5 5 5 5	0 0 0 0	0 0 0 0	0	0	0	0
45.8	5 5 5 5	0 0 0 0	0 0 0 0	0	0	0	0
95.1	5 5 5 5	0 0 0 0	0 0 0 0	0	0	0	0
191	5 5 5 5	0 0 0 0	0 0 0 0	1*	0	0	0
385	5 5 5 5	0 0 0 0	0 0 0 2	0	10	0	0
908	5 5 5 5	0 0 0 0	3 3 5 5	0	80	0	0

* At the test item concentration of 191 μg/L one animal died during handling and was therefore excluded from statistical analyses as this was not a substance related effect.

Table 2. EC-Values, NOEC and LOEC of the test item
Endpoint [μg test item/L]	24 hours	48 hours
EC50	>908	706
95 % CI	n.d.	600 - 831
EC20	>908	506
95 % CI	n.d.	388 - 660
EC10	>908	406
95 % CI	n.d.	284 - 580
NOEC	≥908	191
LOEC	>908	385
Values refer to time weighted average test concentrations CI: Confidence interval n.d.: not determinable.

 

All reported results refer to time weighted average concentrations, since the test item concentrations were not within ± 20 % of the measured initial concentrations during the test.

 

Environmental conditions

pH, oxygen concentrations, and temperature during the study were inconspicuous:

Water Temperature:	18.4 to 18.6 °C in the freshly prepared media 18.6 to 18.9 °C in the aged test media
pH-Values:	7.7 to 7.8 in the freshly prepared media 7.7 to 7.8 in the aged test media
Dissolved Oxygen Concentration:	9.4 to 9.6 mg/L in the freshly prepared media; 9.3 to 9.5 mg/L in the aged test media

No remarkable observations were made concerning the appearance of the test item in test media. All test media were clear solutions and remained clear throughout the entire test period.

 

Analytical results

Table 3. Summary of Analytical Results

Sample Description [mg test item/L]	Initial Mean^1 [mg test item/L]	Time Weighted Average^1,2 [mg test item/L]
Control	n.a.	n.a.
1:16 Dilution	91.8	45.8
1:8 Dilution	184	95.1
1:4 Dilution	370	191
1:2 Dilution	729	385
WSF of 100 mg/L	1690	908

^1 Mean value of all measured samples per treatment group ^2 Calculated according to OECD Guidance Document No. 23, Annex 2 The tabulated results represent results rounded to three significant digits WSF: water soluble fraction n.a.: not applicable

 

Validity criteria fulfilled:

yes

Conclusions:

Under the conditions of this study the 48-h EC50 value was calculated to be 706 μg test item/L (95 % CI: 600 – 831 mg/L).

Executive summary:

The acute toxicity of the test item to Daphnia magna was assessed in a 48-h Acute Immobilisation Test according to OECD TG 202. For this purpose, juvenile Daphnia magna were exposed in a semi-static test to various concentrations under defined conditions for 48 hours. Due to the low limit of water solubility of the test item a Water Soluble Fraction (WSF) of nominal 100 mg/L and dilutions of 1:2, 1:4, 1:8 and 1:16 of this WSF were tested. Additionally, a control was tested in parallel. The study comprised four test vessels per concentration containing five Daphnia magna each, i.e. 20 daphnids per concentration (test medium group) and control group. The purpose of the analytical part of this study was to verify the concentrations of the test item in the test medium. The limit of quantification of the analytical method was 0.01 mg/L. The analytically determined concentrations were 45.8, 95.1, 191, 385 and 908 µg test item/L. Since the test item concentrations were not within ± 20 % of the measured initial concentrations during the test, all reported results refer to time weighted average concentrations After 48 hours of exposure no immobilisation of the test animals was observed in the control and up to and including the test item concentration of 191 μg test item/L. At the concentration of 385 μg test item/L, two daphnids were immobile and 16 daphnids were immobile at the concentration of 908 μg test item/L. Under the test conditions, the 24-h EC₅₀ of the item was determined to be > 908 µg/L (95 % CI: not determinable) and the 48-h EC₅₀ was determined to be 706 µg/L (95 % CI: 600 - 831 µg/L).

Description of key information

The test item showed a 48-h EC₅₀ of 706 µg/L (95 % CI: 600 - 831 µg/L) in a study performed according to OECD Guideline 202 (reference 6.1.3-1).

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Dose descriptor:

EC50

Effect concentration:

706 µg/L

Additional information

The acute toxicity of the test item to Daphnia magna was assessed in a 48-h Acute Immobilisation Test according to OECD TG 202. For this purpose, juvenile Daphnia magna were exposed in a semi-static test to various concentrations under defined conditions for 48 hours. Due to the low limit of water solubility of the test item a Water Soluble Fraction (WSF) of nominal 100 mg/L and dilutions of 1:2, 1:4, 1:8 and 1:16 of this WSF were tested. Additionally, a control was tested in parallel. The study comprised four test vessels per concentration containing five Daphnia magna each, i.e. 20 daphnids per concentration (test medium group) and control group. The purpose of the analytical part of this study was to verify the concentrations of the test item in the test medium. The limit of quantification of the analytical method was 0.01 mg/L. The analytically determined concentrations were 45.8, 95.1, 191, 385 and 908 µg test item/L. Since the test item concentrations were not within ± 20 % of the measured initial concentrations during the test, all reported results refer to time weighted average concentrations After 48 hours of exposure no immobilisation of the test animals was observed in the control and up to and including the test item concentration of 191 μg test item/L. At the concentration of 385 μg test item/L, two daphnids were immobile and 16 daphnids were immobile at the concentration of 908 μg test item/L. Under the test conditions, the 24-h EC₅₀ of the item was determined to be > 908 µg/L (95 % CI: not determinable) and the 48-h EC₅₀ was determined to be 706 µg/L (95 % CI: 600 - 831 µg/L).