Dibutyl ether

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:

1988

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: No information given whether the study was performed according to GLP.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 203 (Fish, Acute Toxicity Test)

Deviations:

not applicable

Principles of method if other than guideline:

not applicable

GLP compliance:

no

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
not applicable

Analytical monitoring:

yes

Details on sampling:

- Concentrations: 0.1 to approximately 50 mg/l.

Vehicle:

no

Details on test solutions:

All tests were conducted in diluters. Tank volume was 7.0 litres volume change per day was 7.79 litres. The test chemical was prepared for proportional dilution by liquid-liquid equlibrator. Diluted stocks were prepared in 18.9 litres stainless steel carbonation vessels. Lake Superior water plus the liquid or solid toxicant were added to the vessels and stirred or blended vigorously. The carbonation vessels for several test compounds were heated in a water bath, thereby increasing the solubility of the compound in the equilibrator. No solvent carriers were used.
Another form of a liquid-liquid equilibrator was constructed from a 2.8 litre culture flask atop a magnetic stirrer. A pump forced lake water into this closed system which contained a layer of the chemical. This type of solution equilibrator was used with liquid chemicals of varying specific gravities. Which type of liquid-liquid equilibrator was used in the case of dibutyl ether is not mentioned.

Test organisms (species):

Pimephales promelas

Details on test organisms:

TEST ORGANISM
- Common name: fathead minnow
- Strain: Pimephaels promelas
- Source: Environmental Research Laboratory-Duluth culture
- Age at study initiation (mean and range, SD): 31 day old juveniles
- Weight at study initiation (mean and range, SD): measured mean weight of 0.046 grams
- Method of breeding:
- Feeding during test: Test fish were not fed 24 hr before or during a test.

ACCLIMATION
- Health during acclimation (any mortality observed): yes - Only groups of fish having healthy appearance and no history of unusual thermal exposure or abnormally high mortality rate were used for toxicant exposure. Prior to initiating a test, prospective test fish were pooled if reared in more than one tank. At start of a test, individuals were removed from the common pool of fish with a net and distributed at random among twelve test tanks (one control and five different concentrations (0.1 to appr. 50 mg/l), each in duplicate). For each replicate 25 fish were used.

Test type:

flow-through

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Post exposure observation period:

not applicable

Hardness:

Routine measures of hardness (ethylenediaminetetraacetic acid) and total alkalinity of test water yielded mean values of 45.0 and 43.0 mg/l as calcium carbonate (CaCO3), respectively.

Test temperature:

Lake Superior water maintained at 25 ± 1 °C was used in all tests.

pH:

The arithmetic mean of the pH was 7.6

Dissolved oxygen:

Mean value for dissolved oxygen of 7.8 mg/l (oxygen saturation in all tests of this study was always greater than 60 %).

Salinity:

no information available

Nominal and measured concentrations:

Nominal concentrations 0.1 to approximately 50 mg/l were used

Details on test conditions:

Test fish were not fed 24 hr before or during a test. Light/dark regime was 16 hours/8 hours. Prior to initiating a test, prospective test fish were pooled if reared in more than one tank. At start of a test, individuals were removed from the common pool of fish with a net and distributed at random among twelve test tanks (one control and five different concentrations (0.1 to appr. 50 mg/l), each in duplicate). For each replicate 25 fish were used.
All tests were conducted in diluters. Tank volume was 7.0 litres, volume change per day was 7.79 litres. The test chemical was prepared for proportional dilution by liquid-liquid equlibrator. Diluted stocks were prepared in 18.9 l stainless steel carbonation vessels. Lake Superior water plus the liquid or solid toxicant were added to the vessels and stirred or blended vigorously. The carbonation vessels for several test compounds were heated in a water bath, thereby increasing the solubility of the compound in the equilibrator. No solvent carriers were used. Another form of a liquid-liquid equilibrator was constructed from a 2.8 l culture flask atop a magnetic stirrer. A pump forced lake water into this closed system which contained a layer of the chemical. This type of solution equilibrator was used with liquid chemicals of varying specific gravities. Which type of liquid-liquid equilibrator was used in the case of dibutyl ether is not mentioned.
The number of dead fish was noted 1, 3, 6, 24, 30, 48, 54, 72, 78, and 96 hrs after the beginning of the test, at which time they were also removed

Reference substance (positive control):

no

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

32.3 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Remarks on result:

other: 95% CL (30.1 - 34.7 mg/l). Rounded numbers (LC50 32 mg/l (95 %CL 30-35 mg/l)) were used in the SIAR.

Duration:

96 h

Dose descriptor:

other: 95%CI

Effect conc.:

30.1 - 34.7 mg/L

Details on results:

The 96 hour LC50 of dibutyl ether to Pimephales promelas was 32.3 mg/l with 95% CL of 30.1 - 34.7 mg/l, however, rounded off values (LC50 32 mg/l (95 %CL 30-35 mg/l)) were used in the SIAR.

Results with reference substance (positive control):

not applicable

Reported statistics and error estimates:

The LC50 was computed using the trimmed Spearman-Kärber method

Sublethal observations / clinical signs:

At the highest concentration (corrected average of measured concentrations = 52.5 and 49.4 mg/l, respectively) 100 % mortality occurred after 1 h of exposure.

Validity criteria fulfilled:

yes

Conclusions:

Under the conditions of the study, the 96 hour LC50 of dibutyl ether to Pimephales promelas was 32.3 mg/l with 95% CL of 30.1 - 34.7 mg/l, however, rounded off values (LC50 32 mg/l (95 %CL 30-35 mg/l)) were used in the SIAR.

Executive summary:

In this study, 31-day-old juvenile fathead minnows (Pimephales promelas, Environmental Research Laboratory-Duluth culture) with a measured mean weight of 0.046 g were used in this toxicity test. Only groups of fish having healthy appearance and no history of unusual thermal exposure or abnormally high mortality rate were used for toxicant exposure. 

Test fish were not fed 24 hr before or during a test. Light/dark regime was 16 hours/8 hours. Prior to initiating a test, prospective test fish were pooled if reared in more than one tank. At start of a test, individuals were removed from the common pool of fish with a net and distributed at random among twelve test tanks (one control and five different concentrations (0.1 to appr. 50 mg/l), each in duplicate). For each replicate 25 fish were used.

All tests were conducted in diluters. Tank volume was 7.0 litres, volume change per day was 7.79 litres. The test chemical was prepared for proportional dilution by liquid-liquid equlibrator. Diluted stocks were prepared in 18.9 l stainless steel carbonation vessels. Lake Superior water plus the liquid or solid toxicant were added to the vessels and stirred or blended vigorously. The carbonation vessels for several test compounds were heated in a water bath, thereby increasing the solubility of the compound in the equilibrator. No solvent carriers were used. Another form of a liquid-liquid equilibrator was constructed from a 2.8 l culture flask atop a magnetic stirrer. A pump forced lake water into this closed system which contained a layer of the chemical. This type of solution equilibrator was used with liquid chemicals of varying specific gravities. Which type of liquid-liquid equilibrator was used in the case of dibutyl ether is not mentioned.

The number of dead fish was noted 1, 3, 6, 24, 30, 48, 54, 72, 78, and 96 hrs after the beginning of the test, at which time they were also removed.

 The LC50 was computed using the trimmed Spearman-Kärber method. Under the conditions of the study, the 96 hour LC50 of dibutyl ether to Pimephales promelas was 32.3 mg/l with 95% CL of 30.1 - 34.7 mg/l, however, rounded off values (LC50 32 mg/l (95 %CL 30-35 mg/l)) were used in the SIAR. At the highest concentration (corrected average of measured concentrations = 52.5 and 49.4 mg/l, respectively) 100 % mortality occurred after 1 h of exposure.

Description of key information

A 96-hour flow-through toxicity study was available for dibutyl ether (DnBE) exposed to fathead minnows (Pimephales promelas). The 96-hr LC50 value was reported as 32.3 mg/L (95% C.L. 30.1-34.7 mg/L).

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

32.3 mg/L

Marine water fish

Marine water fish

Effect concentration:

450 mg/L

Additional information

A total of five freshwater and one saltwater acute toxicity tests with fishes exposed to dibutyl ether (DnBE) are available, all following available guidelines and receiving Klimisch scores of 2, having been conducted prior to the requirement for GLP certification. The key study, was conducted in a flow-through system with the fathead minnow (Pimephales promelas) for 96 hours and reported an LC50 value of 32.3 mg/L (95% C.L. 30.1-34.7 mg/L). This study is supported by five additional studies that include a second 96-hr flow-through exposure with Pimephales promelas (LC50 = 32.5 mg/L) and a 48-hr semi static test with Oryzias latipes that determined an LC50 value of 30.7 mg/L . Two supporting studies with Leuciscus idus melantous reported 48-hr LC50 values of 71 and 193 mg/L. A saltwater acute test with Cyprinodon variegatus resulted in a 96-hr LC50 value of >450 mg/L.