(E)-4-Ethoxy-1,1,1-trifluoro-3-buten-2-one (stabilized with BHT)

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:

24-26 Apr. 2006

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

The study was conducted according to an internationally recognised method, and under GLP. The substance is adequately characterised with its purity. Therefore full validation applies.

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Version / remarks:

OECD, 2004

Deviations:

yes

Remarks:

Climate chamber temperature between 19.4 and 20.8°C (thus varying more than +/- 1°C). No influence on the results because 20.8°C recorded in only one occasion (air temperature recorded once every hour).

GLP compliance:

yes

Analytical monitoring:

yes

Remarks:

As ETFBO hydrolyses quickly (T1/2 is < 5 min at the test temperature), the concentration in the test solutions was based on the hydrolysis product, 4,4,4-trifluoro-3-oxobutanal (Eicher, 2006).

Details on sampling:

- Concentrations: Concentrations were analysed in both treatments: control (Elendt M4 medium) and exposed to 100 mg/L.
- Sampling method: Samples of 100 μL were taken in triplicate:
* from the diluted stock solution and Elendt M4 medium at the beginning of the study,
* from experimental beakers at the end of the study (on day 2).
- Sample storage conditions before analysis: The samples were analysed on the day of sampling.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: On the day of test initiation, a stock solution was prepared by dissolving 260 mg ETFBO in 250 mL Elendt M4 medium resulting in an ETFBO concentration of 1.04 g/L. This stock solution was diluted ten times with Elendt M4 medium resulting in a stock solution of 104 mg/L.
- Controls: Elendt M4 medium.
- Evidence of undissolved material (e.g. precipitate, surface film, etc.): No undissolved test substance was visible.
- Other relevant information: The test solution with ETFBO was slightly yellow.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Water flea.
- Age at study initiation: 0 - 24h at the start of the test.
- Method of breeding: The water fleas were in culture since 4 February 2003. Water fleas of the same age were cultured in vessels with 2 L Elendt M4 medium. They were fed with an algal suspension of Chlorella vulgaris. The water fleas were cultured in a climate chamber with a temperature setpoint of 20°C. The light regime was 16h light and 8h darkness per day. The light was switched on at 6 a.m. Each week, a new culture of water fleas was started and water fleas older than 2 weeks were removed.
- Source: Water fleas used in this test originate from a culture received on 4 February 2003 from Aquasense b.v., Amsterdam, The Netherlands.
- Age of parental stock: not older than 2 weeks.
No further data.

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Hardness:

No data

Test temperature:

Control:
Day 0 (test initiation): 19.7°C
Day 2 (test end): 20.3°C
100 mg/L:
Day 0 (test initiation): 20.2°C
Day 2 (test end): 20.4°C

pH:

Control:
Day 0 (test initiation): 8.1
Day 2 (test end): 8.2
100 mg/L:
Day 0 (test initiation): 6.5
Day 2 (test end): 7.5

Dissolved oxygen:

Control:
Day 0 (test initiation): 8.9 mg/L
Day 2 (test end): 8.8 mg/L
100 mg/L:
Day 0 (test initiation): 9.0 mg/L
Day 2 (test end): 8.8 mg/L

Nominal and measured concentrations:

Nominal concentrations: 0, and 100 mg/L.
Measured concentrations: 0.04 mg/L to not detected, and 93.9 mg/L (mean of concentrations measured on day 0 and day 2).
N.B.1: As ETFBO hydrolyses quickly (T1/2 is < 5 min at the test temperature), the concentration in the test solutions was based on the hydrolysis product, 4,4,4-trifluoro-3-oxobutanal (Eicher, 2006).
N.B.2: On day 0, a small amount (< lowest calibration standard) of 0.04 mg/L was measured in the control. As the substance was also determined in the blank sample (mobile phase), and no substance was determined in the samples on day 2, it was concluded that the mobile phase was contaminated during sampling on day 0.
N.B.3: The difference between the nominal and the mean measured concentrations was < 20% and for this reason the effect concentrations were based on nominal concentration.

Details on test conditions:

TEST SYSTEM
- Test vessel: glass beakers.
- Volume of solution: 200 mL.
- No. of organisms per vessel: 10.
- No. of vessels per concentration (replicates): 6.
- No. of vessels per control (replicates): 6.
No further data.

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Elendt M4 medium prepared in purified water (purified water was prepared according to the methods of European Pharmacopeia and the USP Purified Water).
- Culture medium different from test medium: No.
- Intervals of water quality measurement: At test initiation, the pH, temperature and oyxgen content were measured in the Elendt medium and the stock solution. At test termination, the pH, temperature and oxygen content was measured in one glass beaker for both treatments.
No further data.

OTHER TEST CONDITIONS
- Adjustment of pH: No.
- Photoperiod: The light regime was 16h light and 8h dark (light on from 6 a.m. to 10 p.m.).
No further data.

EFFECT PARAMETERS MEASURED
The number of mobile and immobile water fleas and the number of water fleas showing sublethal effects were recorded 24 and 48 hours after test initiation. Immobile water fleas are those animals which are not able to swim within 15 seconds after gentle agitation of the glass beaker.

RANGE-FINDING STUDY
- Spacing factor for test concentrations: Not applicable (limit test).
- Range finding study : yes, not detailed except that results allowed to select a limit test design (therefore, it is deduced that no adverse effect was recorded during the range-finding study).

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: The difference between the nominal and the mean measured concentration was < 20% and for this reason the endpoint was based on nominal concentration.

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

>= 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: The difference between the nominal and the mean measured concentration was < 20% and for this reason the endpoint was based on nominal concentration.

Details on results:

BIOLOGICAL RESULTS
No immobility or sublethal effects were observed in the control glass beakers and in the glass beakers containing 100 mg/L ETFBO.

ANALYTICAL RESULTS
As ETFBO hydrolyses quickly (T1/2 is < 5 min at the test temperature), the concentration in the test solutions was based on the hydrolysis product, 4,4,4-trifluoro-3-oxobutanal (Eicher, 2006):
Measured concentrations in the control group:
Day 0 (test initiation): a small amount (< lowest calibration standard) of 0.04 mg/L was measured in the control on day 0. As the substance was also determined in the blank sample (mobile phase), and no substance was determined in the samples on day 2, it was concluded that the mobile phase was contaminated during sampling on day 0. Because no adverse effect was observed, this was judged without effect on the study conclusions.
Day 2 (test end): not detected.
Measured concentrations in the group exposed to the nominal concentration of 100 mg/L:
Day 0 (test initiation): 99.3 mg/L.
Day 2 (test end): 88.5 mg/L.
Mean measured concentration: 93.9 mg/L.
The difference between the nominal and the mean measured concentrations was < 20% and for this reason the effect concentrations were based on nominal concentration.

Results with reference substance (positive control):

- Results with reference substance valid? Yes (24h-EC50 within the acceptance range of 0.6-1.7 mg/L for potassium dichromate) .
- 24h-EC50: 1.28 mg/L (test conducted from 21 to 22 March 2006).

Reported statistics and error estimates:

The NOEC for immobility was determined with Fisher's Exact Test (Sokal and Rohlf, 1981).

Validity criteria fulfilled:

yes

Remarks:

No immobility in the controls and dissolved oxygen concentrations at the end of the test > 3 mg/L.

Conclusions:

No adverse effects on water fleas were observed upon acute exposure and the 48h-EC50 (Daphnia magna) was set superior to the highest tested concentration of 100 mg/L.

Executive summary:

The acute toxicity to daphnids was investigated in a GPL-compliant study performed according to OECD test guideline 202.

Groups of ten water fleas (Daphnia magna) were exposed for 48 hours under static conditions to a control treatment and to a treatment exposed to 100 mg/L ETFBO (nominal concentration). Mobility and sublethal effects were observed after 24 and 48 hours.

To study exposure to ETFBO, samples of test solution were taken and analysed with HPLC at the beginning (on day 0) and at the end of the test (on day 2). As ETFBO hydrolyses quickly (T1/2 is < 5 min at the test temperature), the concentration in the test solutions was based on the hydrolysis product, 4,4,4-trifluoro-3-oxobutanal (Eicher, 2006). The mean of concentrations measured on day 0 and day 2 was equal to 93.9 mg/L; meaning that the difference between nominal and measured concentrations was < 20 % and that effect concentrations could be thus based on nominal concentrations.

Because neither immobility, nor sublethal effects were observed in the group exposed to the concentration of 100 mg/L, the 48h-NOEC and 48h-EC50 were respectively set >= and > to this concentration. It can be thus concluded that initial exposure to ETFBO and then to its hydrolysis product did not cause any adverse acute effect on Daphnia magna under the present experimental conditions.

Description of key information

Because neither immobility, nor sublethal effects were observed in the group exposed to the concentration of 100 mg/L, the 48h-NOEC and 48h-EC50 were respectively set >= and > to this concentration. It can be thus concluded that initial exposure to ETFBO and then to its hydrolysis product did not cause any adverse acute effect on Daphnia magna under the present experimental conditions.

Additional information

An experimental study, conducted according to OECD guideline and GLP, is available. It is considered as fully reliable, and the result is retained as key data.