Chlorimuron ethyl

Short-term toxicity to fish

Administrative data

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2011

Report date:

2011

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

EPA OPPTS 850.1075 (Freshwater and Saltwater Fish Acute Toxicity Test)

Deviations:

no

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

ethyl 2-({[(4-chloro-6-methoxypyrimidin-2-yl)carbamoyl]amino}sulfonyl)benzoate

EC Number:

618-690-2

Cas Number:

90982-32-4

Molecular formula:

C15H15ClN4O6S

IUPAC Name:

ethyl 2-({[(4-chloro-6-methoxypyrimidin-2-yl)carbamoyl]amino}sulfonyl)benzoate

Test material form:

solid: crystalline

Details on test material:

Purity: 97.5%

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

- Sampling method: Samples were collected from each test chamber at test initiation and at 48 and 96 hours (± 1 hour) to measure concentrations of the test substance. The samples were collected at mid-depth and placed in glass vials. Two sets of samples were collected at each interval. One set was processed immediately for analysis.
- Sample storage conditions before analysis: The second set was stored refrigerated for possible future analysis.

Test solutions

Vehicle:

yes

Remarks:

Filtered saltwater

Details on test solutions:

Preparation of Test Concentrations:
The 120 mg a.s./L test solution, which served as a primary stock for the lower test concentration solutions, was prepared by weighing 3.6810 grams of the test substance and adding it to 30 L of filtered saltwater. The 120 mg a.s./L test solution was stirred overnight (~20 hours) with a top-down electric mixer. Aliquots of the 120 mg a.s./L test solution were proportionally diluted with filtered saltwater to prepare four additional test solutions at nominal concentrations of 7.5, 15, 30 and 60 mg a.s./L. The 7.5, 15, 30 and 60 mg a.s./L test solutions were mixed approximately 1-2 minutes with a top-down electric mixer. The solutions were adjusted to 100% active substance based up an active substance content of 97.8% as provided on the test substance label. At test initiation and test termination all test solutions appeared clear and colorless, with no visible precipitate.

Test organisms

Test organisms (species):

Cyprinodon variegatus

Details on test organisms:

TEST ORGANISM
- Common name: sheepshead minnow
- Strain: Cyprinodon variegatus
- Source: Aquatic Bio Systems, Fort Collins, Colorado
- Age at study initiation: Juveniles
- Weight at termination: 0.12 - 0.26 g
- Loading: 0.090 g fish/L

ACCLIMATION
- Acclimation period: At least 14 days
- Acclimation conditions: Temperature: 21.9 to 23.7°C; pH: 7.6 to 8.3; Dissolved oxygen: 6.6 to 8.1 mg/L (84% of saturation); Salinity: 20 to 21 parts per thousand (‰)
- Type and amount of food during acclimation: Fed a diet of Artemia. The fish were not fed for at least two days prior to the test or during the test.
- Feeding frequency during acclimation: Daily during the holding period
- Health during acclimation: No signs of disease or stress

FEEDING DURING TEST
- Test period: unfed

Study design

Test type:

static

Water media type:

saltwater

Total exposure duration:

96 h

Test conditions

Test temperature:

21.7 to 23.9°C in test chambers; 22 to 23°C measured continuously in the negative control.

pH:

7.9 to 8.2

Dissolved oxygen:

5.9 to 7.5 mg/L

Salinity:

20‰

Nominal and measured concentrations:

Nominal: 7.5, 15, 30, 60 and 120 mg/L
Measured: 7.4, 15, 30, 57 and 120 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 25 L stainless steel aquaria containing 15 L of test solution; depth of the test water in a representative chamber was 18.0 cm.
- Aeration: Unaerated
- No. of organisms per vessel: 7 fish per test chamber

TEST MEDIUM
- Source/preparation of dilution water: Natural seawater collected at Indian River Inlet, Delaware. The freshly-collected seawater was passed through a sand filter to remove particles greater than approximately 25 μm, and pumped into a 37,800 L storage tank. The filtered saltwater then was diluted to a salinity of approximately 20‰ with freshwater from a well and was aerated with spray nozzles. Prior to use, the 20‰ water was filtered to 0.45 μm to remove fine particles.

OTHER TEST CONDITIONS
- Photoperiod: 16 hr light and 8 hr dark including 30 min transitional period preceding and following the 16 hr light interval.
- Light intensity: 426 lux at initiation

Reference substance (positive control):

no

Results and discussion

Effect concentrations

Effect concentrations 1

Key result

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

> 120 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

act. ingr.

Basis for effect:

mortality (fish)

Effect concentrations 2

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

120 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

act. ingr.

Details on results:

All fish in the negative control group and in all treatment groups appeared normal throughout the test, with no observed mortality or sublethal effects.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

96-Hour LC50: >120 mg/L (Mortality)
96-Hour NOEC: 120 mg/L

Executive summary:

The acute toxicity of the test substance to unfed juvenile sheepshead minnow (Cyprinodon variegatus), a saltwater fish, was determined in an unaerated, static, 96-hour dose response test. The test was conducted in accordance with the Test Guideline OPPTS Number 850.1075, Fish Acute Toxicity Test, Freshwater and Marine. Treatments consisted of a dilution water control and nominal test substance concentrations of 7.5, 15, 30, 60 and 120 mg active substance/L.

One test chamber was maintained in each treatment and control group, with seven sheepshead minnows in each test chamber. Observations of mortality and other signs of toxicity were made approximately 5, 24, 48, 72 and 96 hours after test initiation.

The 96-hour LC50 for Cyprinodon variegatus based on mean, measured concentrations of the test substance and mortality was greater than 120 mg/L.