3-methyl-3-(2,2,3,3,3-pentafluoropropoxy)methyl oxetane

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:

10 April 2018 - 08 June 2018

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:

The concentration and stability of the test item in the test preparations were verified by chemical analysis at 0, 24 and 48 hours.

Vehicle:

yes

Details on test solutions:

Reconstituted water (Elendt M7 medium) was used as the test water. A positive control used potassium dichromate as the reference item but was conducted at a separate time between 23 January 2018 and 25 January 2018.

A preliminary range finding test was conducted to determine the test concentrations to be used in the definitive test.

In the definitive test, a nominal amount fo test item (200 mg) was dissolved in water and the volume adjusted to 2 L to give the 100 mg/L test concentration from which a series of dilutions was made to give further test concentrations.

Test organisms (species):

Daphnia magna

Details on test organisms:

- Age of stock: Less than 24 hours old
- Fed daily with a mixture of algal suspension (Desmodesmus subspicatus) and Tetramin flake food suspension. During exposure, the daphnids received no food.
- Adult daphnids were maintained in 150 mL glass beakers containing 100 mL Elendt M7 medium in a temperature controlled room.
-Culture conditions ensured that reproduction was by parthenogenesis. Gravid adults were isolated the day before initiation of the test, such that young daphids produced overnight were less than 24 hours old.

Test type:

semi-static

Water media type:

freshwater

Total exposure duration:

48 h

Hardness:

Not measured

Test temperature:

18 to 22 °C

pH:

7.9 to 8.1

Dissolved oxygen:

8.9 to 9.7 mg O2/L

Salinity:

Not measured

Conductivity:

Not measured

Nominal and measured concentrations:

The test preparations were measured at 0 and 24 hours and range from 5.8 to 31 mg/L.

Details on test conditions:

TEST SYSTEM
- Test vessel: 150 mL glass beakers containing approximately 100 mL of test preparation.
- No. of organisms per vessel: Five daphnids in each test and control vessel.
- No. of vessels per concentration (replicates): Four replicate tests and control vessels were prepared.
- No food was received during exposure.

TEST MEDIUM
- Reconstituted water (Elendt M7 medium). The pH of the prepared media was 7.9 and stored at 21 °C.

OTHER TEST CONDITIONS
- 16 hours light and 8 hours of darkness

RANGE-FINDING STUDY
- Test concentrations: 0.10, 1.0, 10 and 100 mg/L
- Results used to determine the conditions for the definitive study: The results of the initial range finding test showed an unusual immobilisation pattern therefore a second range finding test was conducted using the same nominal test concntrations as the initial range finding test. The second and third range finding tests were described as an initial experiment and are reported below.

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

58 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

mobility

Key result

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

22 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

LOEC

Effect conc.:

36 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

Range finding test
No immobilization was observed at the test concentrations of 0.10, 1.0 and 10 mg/L, however, 50% immobilization was observed at 100 mg/L. Based on this information 10, 18, 32, 56 and 100 mg/L were selected for the definitive test.

Chemical analysis of the test preparations at 0 hours showed measured test concentrations to range from 9.1 to 76 mg/L. There was a significant decline in the measured concentrations at 48 hours indicating that the test item was not stable under test conditions.

Definitive test
Analysis of the freshly prepared test preparations at 0 and 24 hours showed test concentrations to range from 7.8 to 67 mg/L. Analysis of old or expired test preparations at 24 and 48 hour showed measured test concentrations had declined, to range from 5.8 to 31 mg/L. Even analysis of additional samples containing no daphnids showed a decline in the measured concentrations indicating that the losses observed were primarily attributable to adsorption to the glassware. The results are therefore calculated based on the 0 hour measured test concentrations.

Analysis of the immobilization data by probit analysis using Linear Maximum-Likelihood regression at 24 and 48 hours based on the 0 hour measured test concentration gave the following results;
48 h EC50 = 58 mg/L
48 h NOEC = 22 mg/L
48 h LOEC = 36 mg/L

The test was considered valid given that no more than 10% of the control daphnids showed immobilization or other signs of disease or stress and that the oxygen concentration at the end of the test was equal to or greater than 3 mg/L in the control and test vessels.

Table 1: Cumulative Immobilization Data and Observations in the Third Range-finding Test

Nominal Concentration (mg/L)	24 Hours				48 Hours
	Cumulative Immobilized Daphnia		Observations		Cumulative Immobilized Daphnia		Observations
	Rep1	Rep2	Rep3	Rep4	Rep1	Rep2	Rep1	Rep2
Control	0	0	5 N	5 N	0	0	5 N	5 N
0.1	0	0	5 N	5 N	0	0	5 N	5 N
1.0	0	0	5 N	5 N	0	0	5 N	5 N
10	0	0	5 N	5 N	0	0	5 N	5 N
100	0	0	5 N	5 N	2	3	3 N	2 N

Table 2: Cumulative Immobilization Data and Observations in Definitive Test

0-Hour Measured Concentration (mg/L)	24 Hours
	Cumulative Immobilized Daphnia (Initial Population: 5 Per Replicate)						Observations
	Rep1	Rep2	Rep3	Rep4	Total	%	Rep1	Rep2	Rep3	Rep4
Control	0	0	0	0	0	0	5 N	5 N	5 N	5 N
7.8	0	0	0	0	0	0	5 N	5 N	5 N	5 N
13	0	0	0	0	0	0	5 N	5 N	5 N	5 N
22	0	0	0	0	0	0	5 N	5 N	5 N	5 N
36	0	0	0	0	0	0	5 N	5 N	5 N	5 N
62	0	0	0	0	0	0	5 N	5 N	5 N	5 N

 

0-Hour Measured Concentration (mg/L)	48 Hours
	Cumulative Immobilized Daphnia (Initial Population: 5 Per Replicate)						Observations
	Rep1	Rep2	Rep3	Rep4	Total	%	Rep1	Rep2	Rep3	Rep4
Control	1	0	0	1	2	10	1 R 3 N	5 N	5 N	1 R 3 N
7.8	0	0	1	1	2	10	1 C 4 N	5 N	4 N	4 N
13	2	0	0	0	2	10	3 N	5 N	5 N	5 N
22	1	1	0	0	2	10	2 R 2 N	3 R 1 N	2 R 3 N	1 R 4 N
36	2	2	1	3	8	40	1 R 2 N	2 P 1 N	4 R	1 R 1 N
62	3	2	2	4	11	55	1 R 1 C	3 R	3 R	1 R

 

Rep = Replicate                C = Covered in debris     R = Reduced mobility     N = Normal        P = Pale

Validity criteria fulfilled:

yes

Conclusions:

Exposure of freshwater invertebrates, Daphnia magna to the test item has been investigated and gave an EC50 of 58 mg/L after 48 hours.

Executive summary:

A study was performed to assess the acute toxicity of the test item to Daphnia magna using OECD Method 202. Following preliminary range finding tests and an initial experiment, 20 daphnids (4 replicates of 5 animals) were exposed to an aqueous solution of the test item at nominal concentrations of 10, 18, 32, 56 and 100 mg/L for 48 hours. The number of immobilized daphnia were recorded after 24 and 48 hours.

Analysis of the freshly prepared test preparations at 0 and 24 hours showed test concentrations ranged from 7.8 to 67 mg/L.  Analysis of old or expired test preparations at 24 and 48 hour showed measured test concentrations had declined, to range from 5.8 to 31 mg/L.  Even analysis of additional samples containing no daphnids showed a decline in the measured concentrations indicating that the losses observed were primarily attributable to adsorption to the glassware.  The results are therefore calculated based on the 0 hour measured test concentrations.  

Analysis of the immobilization data by probit analysis using Linear Maximum-Likelihood regression at 24 and 48 hours based on the 0 hour measured test concentration gave the following results;

48 h EC50 =  58 mg/L

48 h NOEC = 22 mg/L

48 h LOEC = 36 mg/L

Description of key information

A study was performed to assess the acute toxicity of the test item to Daphnia magna using OECD Method 202. Analysis of the immobilization data by probit analysis using Linear Maximum-Likelihood regression at 24 and 48 hours based on the 0 hour measured test concentration gave the following results;

48 h EC50 =  58 mg/L

48 h NOEC = 22 mg/L

48 h LOEC = 36 mg/L

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

58 mg/L