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

Short-term toxicity to fish

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

key study

Study period:

04-08 Sept. 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 203 (Fish, Acute Toxicity Test)

Version / remarks:

OECD, 1992

Deviations:

no

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 (ISO water) and exposed to 100 mg/L.
- Sampling method: Samples of 100 µL were taken in triplicate:
* from the stock solution and ISO water at the beginning of the study,
* from aquariums on day 2 (before and after renewal) and at the end of the study (on day 4).
- Sample storage conditions before analysis: The samples were stored at 2 - 8°C for a maximum of 7 days.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: On the day of test initiation and after 48h, stock solutions were prepared in test aquaria by dissolving 401.5 and 404.0 mg ETFBO in 4 L ISO water resulting in ETFBO concentrations of 100 mg/L (at test initiation) and 101 mg/L (after 48h), respectively. The stock solutions were stirred for about 30 min.
- Controls: 4 L ISO water.
- Evidence of undissolved material: No undissolved test substance was visible.
- Other relevant information: The test solution with ETFBO was slightly yellow.

Test organisms (species):

Danio rerio (previous name: Brachydanio rerio)

Details on test organisms:

TEST ORGANISM
- Common name: Zebra fish.
- Source: Zebra fish used in this test originate from a commercial supplier (De Rifwachter, Hilversum, The Netherlands). The fish arrived at the test laboratory on 23 August 2006.
- Weight at study initiation: 0.405 g per fish (mean for 10 fish).
No further data.

ACCLIMATION
- Acclimation period: From 23 August to 04 September 2006.
- Acclimation conditions: The fish were kept in climate chamber with a temperature setpoint of 23°C in a plastic container with 100 L ISO water. The light regime was 14h light and 10h dark (light on from 8 a.m. to 10 p.m.). The water was filtered continuously to assure acceptable water quality.
- Type of food during acclimation: The fish were fed with Tetramin and living water fleas.
- Particular observations before test initiation: No aberrant behaviour or appearance of the fish was observed at the day of test initiation.
No further data.

FEEDING DURING TEST
The fish were not fed during the 24h period prior to the test and during the test.

Test type:

semi-static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

96 h

Hardness:

No data

Test temperature:

Control:
Day 0 (test initiation): 23.3°C
Day 2 (before renewal): 23.9°C
Day 2 (after renewal): 23.0°C
Day 4 (test end): 23.6°C
100 mg/L:
Day 0 (test initiation): 23.2°C
Day 2 (before renewal): 23.9°C
Day 2 (after renewal): 23.2°C
Day 4 (test end): 23.6°C

pH:

Control:
Day 0 (test initiation): 8.3
Day 2 (before renewal): 8.5
Day 2 (after renewal): 8.3
Day 4 (test end): 7.8
100 mg/L:
Day 0 (test initiation): 6.5
Day 2 (before renewal): 7.6
Day 2 (after renewal): 6.7
Day 4 (test end): 7.1

Dissolved oxygen:

Control:
Day 0 (test initiation): 8.6 mg/L
Day 2 (before renewal): 8.0 mg/L
Day 2 (after renewal): 8.5 mg/L
Day 4 (test end): 8.2 mg/L
100 mg/L:
Day 0 (test initiation): 8.6 mg/L
Day 2 (before renewal): 5.8 mg/L
Day 2 (after renewal): 8.5 mg/L
Day 4 (test end): 7.0 mg/L
N.B. There is no explanation for the lower value on day 2 before renewal (i.e. 5.8 mg/L). As this value is higher than 60 % of the air saturation value (i.e. ca. 5.2 mg/L at 23 °C), this means that the test conditions were suitable for the fish.

Nominal and measured concentrations:

Nominal concentrations: 0 and 100 mg/L.
Measured concentrations: not detected and 86.9 mg/L (mean of concentrations measured on day 0, day 2 before renewal, day 2 after renewal and day 4).
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: 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: aquarium with length, width and height of 30, 20 and 15 cm, respectively.
- Type: closed with plastic plates.
- Volume of solution: 4 L.
- Aeration: The test solutions were continuously aerated during the test.
- Renewal rate of test solution: Test solutions were renewed after 48h.
- No. of organisms per vessel: 7.
- No. of vessels per concentration (replicates): 1.
- No. of vessels per control (replicates): 1 .
- Biomass loading rate: 0.405 g x 7 fish / 4 L = 0.71 g/L.

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: ISO water prepared in purified water (purified water was prepared according to the methods of European Pharmacopeia and the USP Purified Water):
* CaCl2.2H2O: 294 mg/L.
* MgSO4.7H2O: 123 mg/L.
* NaHCO3: 64 mg/L.
* KCl: 5.8 mg/L.
- Culture medium different from test medium: No.
- Intervals of water quality measurement: On day 0 and on day 2 (before renewal), the pH, oxygen content and temperature were measured in ISO water and test solutions. On day 2 (after renewal) and on day 4, the pH, oxygen content and temperature were measured in test aquaria.
No further data.

OTHER TEST CONDITIONS
- Adjustment of pH: No.
- Photoperiod: 14h light and 10h dark (light on from 8 a.m. to 10 p.m.).
No further data.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable)
Survival, behaviour and appearance of fish were recorded after 3, 24, 48, 72 and 96h. At the end of the test, the total length (tail included) of each fish was determined.

TEST CONCENTRATIONS
- 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):

no

Key result

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

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:

96 h

Dose descriptor:

NOEC

Effect conc.:

>= 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

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 mortality was observed in the control aquarium. Neither mortality, nor effects on behaviour and general appearance were observed in the fish group exposed to the concentration of 100 mg/L. At the end of the study, the mean length of fish was 2.9 cm in both groups (i.e. control and exposed to 100 mg/L).

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: not detected on all measurement occasions.
Measured concentrations in the group exposed to the nominal concentration of 100 mg/L:
Day 0 (test initiation): 93.6 mg/L
Day 2 (before renewal): 81.3 mg/L
Day 2 (after renewal): 92.2 mg/L
Day 4 (test end): 80.2 mg/L
Mean measured concentration: 86.9 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.

Reported statistics and error estimates:

In the absence of any effect, no statistics were carried out and the NOEC and the LC50 were respectively set >= and > to the highest tested concentration.

Validity criteria fulfilled:

yes

Remarks:

No mortality in controls, dissolved oxygen concentrations > 60 % air saturation value throughout the test, constant conditions and measured concentrations deviating less than 20% from nominal.

Conclusions:

No adverse effects on fish were observed upon acute exposure and the 96h-LC50 (Danio rerio) was set superior to the highest tested concentration of 100 mg/L.

Executive summary:

The acute toxicity to fish was investigated in a GPL-compliant study performed according to OECD test guideline 203.

Groups of seven zebra fish (Danio rerio) were exposed for 96 hours under semi-static conditions (renewal after 48 hours) to a control treatment and to a treatment exposed to 100 mg/L ETFBO (nominal concentration). Mortality, behaviour and general appearance were observed after 3, 24, 48, 72 and 96 hours.

To study exposure to ETFBO, samples of test solution were taken and analysed with HPLC at the beginning of the test (on day 0), before renewal (on day 2), after renewal (on day 2) and at the end of the test (on day 4). 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, day 2 before and after renewel and day 4 was equal to 86.9 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 mortality, nor effects on behaviour and general appearance were observed in the fish group exposed to the concentration of 100 mg/L, the 96h-NOEC and 96h-LC50 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 Danio rerio under the present experimental conditions.

Description of key information

Because neither mortality, nor effects on behaviour and general appearance were observed in the fish group exposed to the concentration of 100 mg/L, the 96h-NOEC and 96h-LC50 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 Danio rerio 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.