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short-term toxicity to fish
Type of information:
experimental study
Adequacy of study:
key study
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Guideline study conducted under GLP

Data source

Reference Type:
study report
Report date:

Materials and methods

Test guideline
according to guideline
OECD Guideline 203 (Fish, Acute Toxicity Test)
slight variation in temperature that did not affect test results
GLP compliance:

Test material

Constituent 1
Chemical structure
Reference substance name:
EC Number:
EC Name:
Cas Number:
Molecular formula:
Details on test material:
- Name of test material (as cited in study report): n-Butyronitrile
- Physical state: Clear, colorless liquid
- Analytical purity: 99.937%
- Lot/batch No.: T-11

Sampling and analysis

Analytical monitoring:
Details on sampling:
Measurements for physical parameters were performed from aliquots withdrawn from standpipes positioned at approximately mid-depth of the minnow test vessel exposure solutions. The temperature, dissolved oxygen concentration, and pH of each exposure solution were measured at time 0 and at 24-hour intervals from test start to test end.

Test solutions

Details on test solutions:
A stock solution of the test substance was prepared in a 200-mL volumetric flask containing laboratory dilution water. Tht: exposure solutions were prepared at a nominal concentration of 120 mg/L by the addition of the appropriate amount of the test substance stock solution to glass vessels containing 20 L of dilution water. After the addition of the test substance, the exposure solutions in each test vessel were stirred with a Teflon-coated stir rod prior to the addition of the organisms. All test solutions and controls were prepared in replicates of two.

Test organisms

Test organisms (species):
Pimephales promelas
Details on test organisms:
Juvenile fathead minnows used in the test were obtained from Aquatic BioSystems, Inc., 1300 Blue Spruce Drive, Suite C, Fort Collins, Colorado 80524 and designated Lot# 091998ABS. All organisms for this test were acclimated to the diluent water prior to the test since the same filtered-treated-tempered water and filtered, compressed air used for all laboratory water/aeration processes during the test were supplied continuously to the rearing tanks. All aquatic organism populations used in the laboratory were maintained in this water for at least two weeks before being used in the test.
Juvenile fathead minnows, as uniform in size as possible, were removed from the holding tanks and transferred to collection vessels. Stratified randomization was accomplished by allocating to each vessel no more than 50% of any one set of test organisms at a time. Two additional sets of minnows (7 minnows/set) were sacrificed at the start of the test to determine average wet weight and mean standard length. The average wet weight per minnow for set #1 was 0.35 g and 0.37 g for set #2. The mean standard length for both set #1 and set #2 was 2.97 cm. Biological loading within test vessels was kept below 1.0 g wet weight per liter of test solution.

Study design

Test type:
Water media type:
Limit test:
Total exposure duration:
96 h

Test conditions

~120 mg/L as CaCO3
Test temperature:
The protocol states the temperature of the test will be held within 20 ± 1C. At test start (time 0-hour), the temperatures of the exposure solutions in all test vessels was 22°C. This slight increase in temperature did not adversely affect the study.
Dissolved oxygen:
7.2-8.7 mg/L
Nominal and measured concentrations:
120 mg/L nominal
107 mean measured
Details on test conditions:
The acute aquatic effects limit test was performed in seamless Pyrex® glass 30.5-cm cuboidal chromatography jars, each containing 20 L of exposure solution. The test organisms were placed into each of the replicate test substance concentration vessels and replicate controls vessels. Glass lids were placed on top of each test vessel and sealed with Parafilm. The test vessels were set in a certified hood and test organisms received approximately 8.5 hours of fluorescent lighting each day of the test. Observations for mortality and signs of stress were made during this test at 0, 4, 24, 48, 72, and 96 hours.

Results and discussion

Effect concentrationsopen allclose all
96 h
Dose descriptor:
Effect conc.:
> 107 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mortality (fish)
96 h
Dose descriptor:
Effect conc.:
>= 107 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mortality (fish)
Details on results:
No mortality was observed in either the control or test substance.

Applicant's summary and conclusion

Validity criteria fulfilled:
Executive summary:

The acute toxicity of the test substance to the fathead minnow (Pimephales promelas) was determined in a 96-hour, static, aquatic effects limit test. Replicate exposure solutions were prepared by the addition of the appropriate amounts of the test substance stock solution to glass vessels containing 20 L of dilution water. Samples of the solutions containing the test substance and the control solutions were submitted for chemical analysis. An exposure concentration of 107 mg/L, used throughout this report and in all endpoint calculations for the test solutions, was based on the geometric mean of the analyzed solutions at times 0 and 96 hours, averaged over the two replicates. Analyzed exposure concentration values were determined by gas chromatography with mass spectrometric detection (GC/MS). The 96-hour LC50 values for Pimephales promelas were estimated to be > 107 mg/L. The highest tested concentration causing no mortality (NOEC) within the period of the test was determined to be 107 mg/L. The minnows in the diluent water controls exhibited normal behavior and appearance throughout the test

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