Butyl ethyl ether

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:

2017-08-03 to 2017-11-28

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)

Version / remarks:

The test item is a volatile substance. Therefore sealed test vessels of 120 mL serum glass bottles were used.

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: Lenzing AG, 60930023
- Expiration date of the lot/batch: 30.09.2021

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: store at room temperature in a dark and dry place in tightly closed receptacles
- Stability under test conditions: stable under storage conditions

Analytical monitoring:

yes

Details on sampling:

Substance specific analysis was performed at the test site of biochemA GmbH.
- Nominal concentrations: 0.0 (Sample code: NC - negative control); 76.8 (Sample code: A); 192.0 (Sample code: B); 480.0 (Sample code: C); 1200 (Sample code: D) and 3000 mg/L (Sample code: E)
- Sampling method: The samples of the chemical analysis were taken out of the sealed flask by pipetting quickly after opening. 2 mL of each sample was taken out and filled into 4 mL glass vial which was contained with 2 mL Methanol for stabilization. All samples were stored in the freezer at ≤ -18°C until measuring at the test site.
The sampling and documentation is conducted according to the following specification:
- At the start of the test (0 h), the test solutions NC, A, C and E were sampled before division to the test vessels (each concentration: 2 samples of 2 mL).
- After 24 h exposure: Before renewal test solution of NC, A, C and E were sampled (2 samples of 2 mL per concentration). The fresh test solutions of NC, A, C and the undiluted saturated fraction (E) were sampled before division to the test vessels (2 samples of 2 mL per concentration).
- At the end of the test (48 h): test solution from NC, A and C were sampled (2 samples of 2 mL per concentration). Due to 100 % immobility for test solution E after 24h no fresh test vessels were prepared for 24h – 48h.
Of each sampled treatment, one of the two samples from 0 h, 24 h (before renewal and fresh test solution) and 48 h were sent to the analytical laboratory at the test site.
The second samples were stored as retain samples in the freezer until finalization of the study.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Direct addition of test substance with immediate sealing of the flask and shaking for approximately 24 hours was used to obtain maximum solubility and to reduce loss of test substance through volatilization.
The pipetting scheme shown in "Table 1: Preparation of the test treatment and control" (refer to "Any other information on materials and methods incl. tables") describes the preparation of the test vessels and controls.
The volume of the test solution for the diluted test concentrations were made in one batch for each treatment group. The test concentrations were prepared by diluting the water saturated fraction with M4 medium. After preparation the test solution the total volume was distributed on the replicates. Four replicates with five daphnids each, were prepared for each test item treatment and NC. Into each test vessel, 120 mL test solution was transferred, respectively. All test vessels were filled up to the brim to avoid headspace while sealing with crimp caps. The controls were treated the same way. For the chemical analysis one additional flask of NC, A, C and E without daphnids was prepared and treated the same way.

- Differential loading: (nominal concentrations): 0.0 (Sample code: NC), 76.8 (Sample code: A), 192 (Sample code: B), 480 (Sample code: C), 1200 (Sample code: D), 3000 (Sample code: E) mg/L.
- Controls: yes
- Evidence of undissolved material (e.g. precipitate, surface film, etc.): Up to a nominal loading rate of 1000 mg/L no undissolved material was observed after shaking.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Daphnia magna Straus
- Strain/clone: from the clone breeding of the Federal Environment Agency, department IV 2.4, Berlin
- Source: cultivated at Hydrotox GmbH since October 2012
- Feeding during test: not reported, according to guideline no
- Food type: Desmodesmus subspicatus algae
- Amount: 0.1 mg C × daphnid-1 × day-1
- Frequency: every day on workdays

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Test temperature:

20.5 - 20.9 °C

pH:

The pH was 8.0 – 8.2 in the control and 7.9 – 8.2 in the test item treatments.
See also Table 2: "pH-values and O2 -concentrations measured at the beginning and at the end of the test" in "Any other informations on results incl. tables".

Dissolved oxygen:

7.8 – 8.2 mg/L in the control and 7.5 – 8.2 mg/L in the test item treatment
See also Table 2: "pH-values and O2 -concentrations measured at the beginning and at the end of the test" in "Any other informations on results incl. tables".

Nominal and measured concentrations:

Nominal loading rate in the test vessel [mg/L]: 0, 76.8, 192, 480, 1200, 3000
mean measured test concentration [mg/L]: 0, 55.1, 287.9, 2071.7

Details on test conditions:

TEST SYSTEM
- Test vessel: sealed test vessels of 120 mL serum glass bottles
- Type (delete if not applicable): closed with crimp caps (Alucrimp Cap with inlaid Septum of Silicone/PTFE)
- Material, size, headspace, fill volume: All test vessels were filled up to the brim to avoid headspace while sealing with crimp caps.
- Aeration: not reported
- Renewal rate of test solution (frequency/flow rate): After 24 h exposure, the sealed flasks were opened and the test organisms were transferred to a new set of test vessels with new test solutions by means of a pipette (renewal of test solutions).
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4 (for B and D), 4 + 1 (for A, C, E)
- No. of vessels per control (replicates): 4 + 1
- No. of vessels per vehicle control (replicates): not applicable

TEST MEDIUM / WATER PARAMETERS
The test was performed with M4 medium according to OECD 202 (2004).

OTHER TEST CONDITIONS
- Adjustment of pH: No
- Photoperiod: 16/8 h light/dark

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of immobilization after 24 and 48 h. The swimming capability of the daphnids was determined after 24 h and 48 h exposure.


RANGE-FINDING STUDY: yes
- Direct addition of the test substance into the test medium without sealing resulted in high loss of substance due to the volatile property of the test substance. It was also not possible to dissolve the test material in the test solution without shaking for several hours. The test solution with a nominal loading rate of 4000 mg/L resulted in a considerable amount of non-dissolved test material, visible as droplets on the surface of the test medium. The clear water saturated fraction obtained from the 1000 mg/L loading rate had strong evaporation of the test substance after incubation in the standard test vessels.
Therefore direct addition of test substance with immediate sealing of the flask and shaking for approximately 24 hours was used to obtain maximum solubility and to reduce loss of test substance through volatilization. Up to a nominal loading rate of 1000 mg/L no undissolved material was observed after shaking.
- Test concentrations: 1000 - 4000 mg/L
- Results used to determine the conditions for the definitive study: yes

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

210.5 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: 95%-Cl: 38.4 - 1030.7

Duration:

48 h

Dose descriptor:

other: EC20

Effect conc.:

131.8 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: 95%-Cl: n.d. - 234.9

Duration:

48 h

Dose descriptor:

EC10

Effect conc.:

103.2 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: 95%-Cl: n.d. - 185.1

Duration:

48 h

Dose descriptor:

LOEC

Effect conc.:

192 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

76.8 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

75.7 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: 95%-Cl: n.d.

Duration:

48 h

Dose descriptor:

other: EC20

Effect conc.:

61.4 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: 95%-Cl: n.d.

Duration:

48 h

Dose descriptor:

EC10

Effect conc.:

55.1 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: 95%-Cl: n.d.

Duration:

48 h

Dose descriptor:

LOEC

Effect conc.:

287.9 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

55.1 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

- Behavioural abnormalities: Not reported
- Observations on body length and weight: No
- Other biological observations: Not reported
- Mortality of control: no
- Other adverse effects control: Not reported.
- Abnormal responses: Not reported.
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values:Not reported.
- Effect concentrations exceeding solubility of substance in test medium:Not reported.

Results with reference substance (positive control):

- Results with reference substance valid?: yes
EC-values after 24 h of the reference item potassium dichromate in mg/L were as follows:
EC50: 1.32 (Cl 95 %: 1.24- 1.41 mg/L)
The EC50-value of reference item potassium dichromate after 24 h is in the declared range of 0.6 – 2.1 mg/L according to OECD 202.

Reported statistics and error estimates:

With the statistical software ToxRat Professional 3.2.1

Table 4: Immobility after 24 h and 48 h exposure.

Nominal test item concentration [mg/L]	Immobile Daphnia (replicates 1 - 4)												Immobility [%]
	0 h				24 h				48 h				24 h	48 h
	1	2	3	4	1	2	3	4	1	2	3	4
NC	0	0	0	0	0	0	0	0	0	0	0	0	0	0
76.8	0	0	0	0	2	0	0	0	0	0	0	0	10	10
192	0	0	0	0	0	0	0	1	1	0	2	2	5	25
480	0	0	0	0	0	0	0	0	5	5	5	5	0	100
1200	0	0	0	0	5	5	5	5	-	-	-	-	100	100
3000	0	0	0	0	5	5	5	5	-	-	-	-	100	100

Validity criteria fulfilled:

yes

Conclusions:

The semi-static acute Daphnia magna immobilisation test was performed with five nominal test concentrations between 76.8 mg/L and 3000 mg/L.
In the control, the test item was not detected. The initial measured test item concentrations in the test item treatments were 60.0 – 72.3 % of the nominal concentrations. Therefore EC values were given additionally as measured effective concentrations:
- 48 h EC50 (measured): 75.7 mg/L (95 % C.I. n.d.);
- 48 h EC20 (measured): 61.4 mg/L (95 % C.I. n.d.);
- 48 h EC10 (measured): 55.1 mg/L (95 % C.I. n.d.)
- 48 h NOEC (measured): 55.1 mg/L and
- 48 h LOEC (measured): 287.9 mg/L.
The test is valid according to OECD Test Guideline 202 (13 April 2004).

Executive summary:

The 48 –hr-acute immobilisation test of butyl ethyl ether to Daphnia magna was conducted under semi-static conditions. Daphnids were exposed to control and butyl ethyl ether at measured concentration of 0.0 (control), 55.1, 287.9 and 2071.7 mg/L (nominal concentration of 0.0, 76.1, 480, 3000 mg/L) for 48 hr.  Mortality/immobilization was observed daily.

The 48 – hour EC50 was 75.7 mg butyl ethyl ether/L (determined with the measured effective concentration). 

The 48 – hour NOEC based on mortality/immobilization was 55.1 mg/L.  

Based on the results of this study, butyl ethyl ether would be not classified as acute toxic to D. magna in accordance with the classification system of the CLP.

This study is classified as acceptable and satisfies the guideline requirements for an acute toxicity study with freshwater invertebrates.

 

Results Synopsis

 

Test Organism Age: 2 h 15 min - 20 h 15 min

Test Type: semi-static

 

EC50: 75.7 mg/L                               95% Cl.: n.d.

EC20: 61.4 mg/L                               95% Cl.: n.d.

EC10: 55.1 mg/L                               95% Cl.: n.d.

Endpoint(s) Effected:  Immobility/Mortality

 

Description of key information

The 48 – hr-acute immobilisation test of butyl ethyl ether to Daphnia magna Straus was studied under semi-static conditions according to OECD 202 (2004), OECD 23 (2000) and under GLP. Daphnids were exposed to butyl ethyl ether at nominal concentrations of 0.0, 76.1, 480 and 3000 mg/L and measured concentrations of 0.0, 55.1, 287.9 and 2071.7 mg/L (geometric mean) for 48 hr. Immobilization was observed daily. 

As the measured test item concentrations are not within ± 20 % of the nominal concentrations, according to OECD 202 (2004) and OECD 23 (2000), all results are given in relation to the analytically measured test item concentrations.

The following effect levels - based on the growth rate - are calculated:

- 48 h EC50 (measured): 75.7 mg/L (95 % C.I. n.d.);

- 48 h EC20 (measured): 61.4 mg/L (95 % C.I. n.d.);

- 48 h EC10 (measured): 55.1 mg/L (95 % C.I. n.d.);

- 48 h NOEC (measured): 55.1 mg/L and

- 48 h LOEC (measured): 287.9 mg/L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

75.7 mg/L