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Short-term toxicity to fish

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Reference
Endpoint:
short-term toxicity to fish
Type of information:
experimental study
Adequacy of study:
key study
Study period:
3 March - 3 April 1994
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Remarks:
This study was performed according with the guideline EPA-600/4-90/027, as well as in accordance with GLP principles. However, the water quality of Ohio river water used in test 1-B and test 2 was not properly determined (e.g. dissolved organic carbon), analytical confirmation of test concentrations was not performed and the fish biomass loading was not reported for any of the tests conducted. Therefore, a Klimisch code 2 was assigned. Since test solutions were partly renewed after 48h and the read-across substance TMAH was stable in an algae study, it can be assumed that the exposure was constant.
Qualifier:
according to
Guideline:
other: EPA-600/4-90/027
Deviations:
not specified
Qualifier:
according to
Guideline:
other: ASTM, 1993. Standard E 729-88a, Book of Standards Volume 11.04.
GLP compliance:
yes
Analytical monitoring:
no
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method:
A working stock solution of methyltributylammonium chloride was prepared on the day the test was initiated. The stock solution was prepared on a weight-to-volume basis in a class A volumetric flask.
From this stock solution, five exposure concentrations were prepared for each test.
For test 1-A (reconstituted fresh water, March 3), the exposure solution was prepared with moderately hard reconstituted fresh water, which was prepared with glass-distilled deionized water and reagent grade salts following the procedures outlined in US EPA-600/4-90/027.
For test 1-B (effluent and river water, March 3) and test 2 (effluent and river water, March 30), an effluent solution was prepared with 6.8% effluent (collected from outfall 002, GE-Plastics, Mt. Vernon, Indiana, USA) in Ohio River water on a volume-to-volume basis.

Test solution renewals were accomplished following 48 h of exposure by removing approximately 50% of the original solution and adding the freshly prepared test solutions to equal the original test volume.

Test organisms (species):
Pimephales promelas
Details on test organisms:
TEST ORGANISM
- Common name: Fathead minnow
- Source:
Woodward-Clyde Consultants (WCC) in-house laboratory cultures for the tests performed on March 3 (Test 1-A and B) and Environmental Consulting and Testing in Superior, Winsconson (USA) for the test performed on March 30 (Test 2).
- Age at study initiation (mean and range, SD): Test 1-A and B = 12 days; Test 2 = 5 days
- Feeding during test: Yes
- Frequency: Two hours prior to 48 h renewal
Test type:
semi-static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
96 h
Hardness:
Test 1-A (reconstituted fresh water): 90 (control group only).
Test 1-B (effluent and river water): hardness was not reported.
Test 2 (effluent and river water): 80 (control group only)
Test temperature:
Test 1-A (reconstituted fresh water), test 1-B (effluent and river water) and test 2 (effluent and river water): 25±1°C
pH:
Test 1-A (reconstituted fresh water): 7.76 - 8.50
Test 1-B (effluent and river water) : 7.53 - 8.92
Test 2 (effluent and river water): 5.68 - 7.91
Dissolved oxygen:
Test 1-A (reconstituted fresh water): 7.3 - 8.6
Test 1-B (effluent and river water) : 7.5 - 8.6
Test 2 (effluent and river water): 7.7 - 8.6
Nominal and measured concentrations:
Nominal (mg test material/L):
Test 1-A (reconstituted fresh water) and test 1-B (effluent and river water): Controls (reconstituted fresh water and effluent and river water, respectively), 2.4, 8.1, 27, 90 and 300.
Test 2 (effluent and river water): Control (effluent and river water), 100, 200, 400, 800 and 1600
Details on test conditions:
TEST SYSTEM
- Test vessel: Styrene vessel
- Material, size, headspace, fill volume: Styrene with a capacity of 250 mL filled with 200 mL of test solution
- Aeration: None
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 2

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water:
Test 1-A (reconstituted fresh water) conducted in moderately hard reconstituted fresh water prepared from glass-distilled deionized water and reagent grade salts following the procedures outlined in US EPA-600/4-90/027 and 6.9% effluent solution prepared with Ohio River (USA) water on a volume-to-volume basis.
Test 1-B (effluent and river water) and test 2 (effluent and river water) conducted using an effluent solution prepared with 6.8% effluent (collected from outfall 002, GE-Plastics, Mt. Vernon, Indiana, USA) in Ohio River water on a volume-to-volume basis.
- Alkalinity:
Test 1-A (reconstituted fresh water): 68 (control group only)
Test 1-B (effluent and river water): Not reported
Test 2 (effluent and river water): 62 (control group only)

OTHER TEST CONDITIONS
- Photoperiod: 16 h light / 8 h dark
- Light intensity: 50-100 Ft. candles

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Mortality and behavioral characteristics

TEST CONCENTRATIONS
- Spacing factor for test concentrations:
Test 1-A (reconstituted fresh water) and test 1-B (effluent and river water): Approximately 3
Test 2 (effluent and river water): 2
Reference substance (positive control):
no
Key result
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
> 300 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality
Remarks on result:
other: Test 1-A (reconstituted fresh water)
Key result
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
> 225 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
mortality
Remarks on result:
other: Test 1-A (reconstituted fresh water). EC50 value calculated by reviewer based on MTBAC content of 75% in the test material.
Details on results:
- The effect levels for test 1-B (effluent and river water) were the following (mg test material/L):
LC50: > 300

- The effect levels for test 2 (effluent and river water) were the following (mg test material/L):
LC50: 987.9 (95% CL: 862.2-1131.8)
Validity criteria fulfilled:
not specified
Conclusions:
Fathead minnows (Pimephales promelas) exposed to methyltributylammonium chloride only suffered mortality greater than 50% in the test conducted with a 6.8% effluent solution in Ohio River water (test 2). The resulting 96 h LC50, based on nominal test material concentrations, was equal to 987.9 mg/L. For reconstituted fresh water the nominal 96h-LC50 can be assumed to be > 300 mg/L. This corresponds with a nominal 96h-LC50 of >225 mg MTBAC/L
Executive summary:

In three 96-h acute toxicity studies, Fathead minnow (Pimephales promela) were exposed to 75% methyltributylammonium chloride at the following nominal test material concentrations:

- Test 1-A (conducted with reconstituted fresh water): control (reconstituted fresh water), 2.4, 8.1, 27, 90 and 300 mg/L;

- Test 1-B (conducted with effluent and river water): control (effluent and river water), 2.4, 8.1, 27, 90 and 300 mg/L;

- Test 2 (conducted with effluent and river water): control (effluent and river water), 100, 200, 400, 800 and 1600 mg/L.

 

For tests 1-A and B mortality was not above 50% even at the highest concentration tested. Therefore, the LC50 value can assumed to be higher than the highest nominal test material concentration (300 mg/L, corresponding with 225 mg MTBAC/L). In test 2, conducted with 6.8% effluent solution in Ohio River water, the 96h-LC50 was 987.9 mg/L.

The present toxicity study is classified as reliable with restrictions since the water quality of Ohio river water was not properly determined (e.g. dissolved organic carbon), analytical confirmation of test concentrations was not performed and the fish biomass loading was not reported for any of the tests conducted.

For the evaluation of the intrinsic toxicity of the substance, only the test results with reconstituted water should be used, because in the other tests (applying 6.8% effluent solution in Ohio River water), the test medium is not well defined.

Description of key information

For test 1-A (reconstituted fresh water) the nominal 96h-LC50 can be assumed to be > 300 mg test material/L. This corresponds with a nominal 96h-LC50 of >225 mg MTBAC/L. Test 1-B conducted with 6.8% industrial effluent solution in Ohio River water showed a comparable LC50 value.
The 96h-LC50 for test 2 (6.8% industrial effluent solution in Ohio River water) in which higher MTBAC concentrations were tested, was equal to 987.9 mg/L, based on nominal concentrations.

Key value for chemical safety assessment

Additional information

In three 96-h acute toxicity studies, Fathead minnow (Pimephales promela) were exposed to 75% methyltributylammonium chloride at the following nominal test material concentrations:

- Test 1-A (conducted with reconstituted fresh water): control (reconstituted fresh water), 2.4, 8.1, 27, 90 and 300 mg/L;

- Test 1-B (conducted with industrial effluent in river water): control (effluent in river water), 2.4, 8.1, 27, 90 and 300 mg/L;

- Test 2 (conducted with industrial effluent in river water): control (effluent in river water), 100, 200, 400, 800 and 1600 mg/L.

 

For tests 1-A and B mortality was not above 50% even at the highest concentration tested. Therefore, the LC50 value can assumed to be higher than the highest test concentration (>300 mg test material/L). In test 2, conducted with 6.8% industrial effluent solution in Ohio River water, the 96h-LC50 was 987.9 mg test material/L.

The present toxicity study is classified as reliable with restrictions since the water quality of Ohio river water was not properly determined (e.g.dissolved organic carbon), the fish biomass loading was not reported and analytical confirmation of test concentrations was not performed for any of the tests conducted. Since test solutions were partly (50% of the volume) renewed after 48h and the read-across substance TMAH was stable in an algae study (TMAH Consortium 2005 and Scheerbaum 2001), it can be assumed that the actual exposure to MTBAC was in agreement with the nominal MTBAC concentration.

For the evaluation of the intrinsic toxicity of the substance, only the test results with reconstituted water should be used, because in the other tests (applying 6.8% industrial effluent solution in Ohio River water), the test medium was not well defined.