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Diss Factsheets

Ecotoxicological information

Toxicity to other aquatic organisms

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Administrative data

toxicity to other aquatic vertebrates
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
from October 13 2014 to October 27 2014
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference Type:
study report

Materials and methods

Test guideline
according to guideline
other: US EPA 850.1025
GLP compliance:
yes (incl. QA statement)

Test material

Constituent 1
Chemical structure
Reference substance name:
EC Number:
Cas Number:
Molecular formula:
Test material form:

Sampling and analysis

Analytical monitoring:
Details on sampling:
Water sample collected from each test chamber of each treatment and control group two days prior to the start of the exposure after conditioning the diluter for approximately one day. Water samples also were collected from each test chamber in each treatment and the control group at the beginning of the test and at 48 and 96 hours (± 1 hour) to measure concentrations of the test substance. An additional sample set was also taken at the beginning of the test and at 48 hours for possible analysis if confirmation of measured concentrations was required. The samples were collected from mid-depth, placed in glass vials, and processed immediately for analysis or stored under refrigeration for possible future analysis.

Test solutions

Details on test solutions:
A primary stock solution was prepared daily during the pre-exposure and exposure at a nominal concentration of 800 mg/L and proportionally delivered to each of the test concentrations during the test.
The stock was injected into the diluter mixing chambers assigned to treatment groups at target rates of 2.756, 5.688, 10.938, 21.875, and 43.750 mL/minute respectively, where they were mixed with dilution water delivered at rates of 332, 329, 326, 321, 310 and 288 mL/minute and algal feed suspension delivered at a rate of 18 mL/minute to achieve the desired test concentrations. The negative control received dilution water and algal feed suspension only at a combined rate of 350 mL/min.

Test organisms

Aquatic vertebrate type (other than fish):
other: Oyster
Test organisms (species):
other: Crassostrea virginica
Details on test organisms:
- from Marinetics, Inc., Cambridge, Maryland
- received 10 days prior to exposure initiation and were held in filtered saltwater from the same source as used during the test.

Study design

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

Test conditions

Test temperature:
Dissolved oxygen:
4.8 mg/L
Nominal and measured concentrations:
Nominal: negative control, 6.3, 13, 25, 50, 100 mg/L
Measured: 5.9± 0.190, 13± 0.265, 24± 0.854, 53± 1.15, 100± 1.59 mg/L
Details on test conditions:
Fluorescent light bulbs that emit wavelengths similar to natural sunlight were controlled by an automatic timer to provide a photoperiod of 16 hours of light and 8 hours of darkness. A 30-minute transition period of low light intensity was provided.

Results and discussion

Effect concentrations
96 h
Dose descriptor:
Effect conc.:
> 100 mg/L
Nominal / measured:
Conc. based on:
test mat.
Basis for effect:
other: inhibition of shell growth
Details on results:
The test solutions in the mixing chambers and test chambers appeared clear and colorless at exposure initiation and clear and green due to algae feed at test termination, with no evidence of precipitation observed in any control or treatment solutions. Measured concentrations of the samples ranged from approximately 85 to 100% of nominal.
Percent inhibition of shell growth was calculated relative to the negative control data. Inhibition of shell growth in the 5.9, 13, 24, 53 and 100 mg/L treatment groups was 22, 20, 9, 14 and 24%, respectively

Applicant's summary and conclusion

No concentration resulted in >50% inhibition of shell growth, the 96-hour EC50 was empirically estimated to be >100 mg/L, the highest concentration tested. The NOEC was determined to be 100 mg/L.
Executive summary:

Eastern oysters (Crassostrea virginica) were exposed for 96 hours under flow-through conditions to five concentrations of triasulfuron TGAI ranging from 5.9 to 100 mg/L. The 96-hour EC50 value was greater than 100 mg/L, the highest concentration tested. The NOEC was determined to be 100 mg/L.