4-(4-chlorophenyl)-2-phenyl-2-[(1H-1,2,4-triazol-1-yl)methyl]butanenitrile

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1988-03-02 to 1988-03-04

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EPA OPP 72-2 (Aquatic Invertebrate Acute Toxicity Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Vehicle:

yes

Remarks:

0.05 mL acetone (solvent control)

Details on test solutions:

Technical primary stock standard of 1.17 mg/mL in Nano-grade acetone was prepared and stored at room temperature. Subsequent dilutions of the 1.17 mg/mL stock solution were prepared
in Nano-grade .acetone and used for the fortification of the quality control samples, and in Millipore water for HPLC chromatography standards. All standard preparations
and dilutions were recorded. This method was validated for the recovery of Fenbuconazole in aquatic test water prior to initiation.

Test organisms (species):

Daphnia magna

Details on test organisms:

Test specimens of Daphnia magna were obtained from an in-house daphnid culture which has been maintained by ABC since 1977. The primary culture was obtained from the Columbia National Fisheries Research Laboratory (CNFRL), Columbia, Missouri, in 1977. A trace of the daphnid strain indicated that CNFRL acquired their culture from the U. S. Fish & Wildlife Service Fish Control Laboratory, LaCrosse, Wisconsin, in 1960 and they obtained their culture from Pennsylvania State University in 1954.

Test type:

flow-through

Water media type:

freshwater

Total exposure duration:

48 h

Test temperature:

20 ± 1 °C

pH:

8.1-8.3

Dissolved oxygen:

8.6-8.9 mg/L

Nominal and measured concentrations:

Mean measured: 0.16, 0.31, 0.78, 1.4, and 3.1 mg/L

Nominal: 0.18, 0.36, 0.75, 1.5 and 3.0 mg/L

Details on test conditions:

All daphnids were held in a temperature controlled area at 20 ± 1 °C. The lighting was 50-70 foot candles on a 16-hour daylight photoperiod, with 30 minute dawn and dusk transition periods. During the holding period, the daphnids were fed a suspension of algae (Selenastrum capricornutum) supplemented with a Tetramin/cereal leaves suspension. Only first-instar daphnids (<24 hours old) were selected for testing.

A half-liter proportional diluter system described by Mount and Brungs, utilizing a Hamilton Micro Lab 420 syringe dispenser, was used for the intermittent introduction of Fenbuconazole and diluent water into the test chambers. The system contained 7 sets of four replicate one-liter test chambers, designated as the control, solvent control, and levels III through level 115. Flow-splitting chambers were utilized to thoroughly mix and divide each test concentration for delivery to the test chambers.

To minimize turbulence, the influent water was introduced into the test chambers via 14-gauge hypodermic needles. One-liter glass beaker with notched drains which were covered with 50-mesh stainless steel screen to prevent escape of the daphnids were used as the test chambers. Daphnids were placed in each of the quadruplicate chambers. Aerated well water was delivered to each test chamber at a rate of 4.6 mL/minute, an amount which was sufficient to replace the 1 liter test volume approximately 6.6 times in a 24-hour period.

The test was initiated by random assignment of 10 first-instar Daphnia magna to each of the four replicate test chambers; 40 daphnids were used per concentration. This presents a loading factor of approximately 1 daphnid per 100 mL of solution.
All concentrations were observed at 4, 24 and 48-hours for immobilization and other abnormal effects such as surfacing, erratic movement and/or daphnids laying on the bottom. Test daphnids were not fed during the 48-hour study.

Key result

Duration:

4 h

Dose descriptor:

EC50

Effect conc.:

> 3.1 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

mobility

Key result

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

> 3.1 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

mobility

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

2.2 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

The mean measured concentrations represent 95 ± 8.2% of the nominal concentration. Fortification samples analyzed at each sample day averaged 97 ± 3.7% over a concentration range of 0.117 to 5.85 mg/L.

EC50 was calculated using moving average method. The abnormal effects of immobilization. erratic movement and/or daphnids on the bottom of the test vessels were observed in the 1.4 and 3.1 mg/L test concentrations.

Validity criteria fulfilled:

yes

Conclusions:

The toxicity of Fenbuconazole based on mean measured test concentrations were as follows: 48-hour EC50 = 2.2 mg/L, and 48-hour NOEC = 0.78 mg/L.

Executive summary:

The toxicity of Fenbuconazole on Daphnia magna based on mean measured test concentrations were as follows: 48-hour EC50 = 2.2 mg/L, and 48-hour NOEC = 0.78 mg/L

Description of key information

The toxicity of Fenbuconazole based on mean measured test concentrations were as follows: 48-hour EC50 = 2.2 mg/L, and 48-hour NOEC = 0.78 mg/L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Dose descriptor:

EC50

Effect concentration:

2.2 mg/L