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

Short-term toxicity to fish

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1988-04 to 1988-08

Reliability:

1 (reliable without restriction)

Qualifier:

according to guideline

Guideline:

EPA OPP 72-1 (Fish Acute Toxicity Test)

Deviations:

not specified

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Vehicle:

yes

Remarks:

Acetone

Details on test solutions:

A diluter stock solution (38000 mg a.s./l) was prepared by dissolving 3.93 g of RH-7592 Technical in acetone. The injector volume was adjusted to deliver 0.2 ml of stock to 1.9 L of dilution volume. The resulting nominal concentration regime of RH-7592 Technical was 0.25, 0.50, 1.0, 2.0 and
4.0 mg a.s./L. The solvent control chamber received acetone at 0.1 mL/L, acetone : water ratio.

Test organisms (species):

Lepomis macrochirus

Details on test organisms:

In-house culture

Test type:

flow-through

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Test temperature:

21 to 23°C

pH:

7.3 to 8.1

Dissolved oxygen:

7.4 to 9.3 mg O2/L

Details on test conditions:

The acute lethal toxicity of fenbuconazole to bluegill sunfish (Lepomis macrochirus) was assessed in a 96 hour test, conducted under flow-through conditions, with fish of mean weight 0.21 ± 0.042 g and mean length of 22 ± 1.3 mm. Duplicate groups of ten fish were exposed to a nominal test series of 0.0 (control), 0.0 (0.1 mL acetone/L solvent control), 0.25, 0.50, 1.0, 2.0 and 4.0 mg a.s./L (adjusted for purity). The test vessel volume was 15 liters. he test was conducted at 21 to 23°C with dissolved oxygen levels of 7.4 to 9.3 mg O2/L (87 to 109% of saturation) and at a pH of 7.3 to 8.1. The dilution water was well water.
Exposure levels were monitored by measuring fenbuconazole in samples of test media collected at 0 and 96 hours. An HPLC/UV method of analysis was employed with detection at a wavelength of 220 nm. Measured concentrations at 0-hours were 0.13, 0.18, 0.39, 0.83, and 1.9 mg a.s./L for levels 1-5, respectively. Measured concentrations at 96-hours were 0.13, 0.19, 0.46, 1.0, and 2.6 mg/L for levels 1-5, respectively. No residues of fenbuconazole were detected in the control and solvent control at concentrations greater than the limit of detection (0.058 mg/L) during the study. The mean measured concentrations were 0.13, 0.18, 0.42, 0.92 and 2.2 mg a.s./L (36 to 55% of the nominal concentrations). A white precipitate was noted in the diluter mixing cell and in all test levels after 24 hours indicating incomplete solubility at all concentrations. Concentrations were consistent throughout the study but below 80% of nominal therefore, the mean-measured concentrations were used to determine toxicity values.

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

0.42 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Key result

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

0.68 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Details on results:

Eighteen of twenty fish died in the 0.92 mg/L treatment and twenty of twenty fish died in the 2.2 mg/L treatment after 96-hours of exposure. There was no mortality in any other treatment or in the controls. Signs of toxicity, such as loss of equilibrium, surfacing and quiescence were noted at the 0.92 mg/L treatment level. A precipitate was noted in concentrations =0.42 mg/L at 24-hours and in concentrations =0.13 mg/L for the remainder of the test. The 96h LC50 for fenbuconazole was determined by binomial calculation to be 0.68 mg/L, measured, with 95% confidence limits of 0.42-0.92 mg/L. The NOEC was considered to be 0.42 mg/L (measured) based on the lack of sublethal effects at this and all lower concentrations. The slope of the 96-hour dose-response line was 7.5.

Sublethal observations / clinical signs:

Table 1: Mortality data

Nominal concentration	Mean measured concentration	Mortality
(mg/L)	(mg/L)	24 h	48 h	72 h	96 h
Control	ND (<0.058)	0	0	0	0
Solvent control	ND (<0.058)	0	0	0	0
0.25	0.13	0	0	0	0
0.50	0.18	0	0	0	0
1.0	0.42	0	0	0	0
2.0	0.92	10/20*	13/20*	17/20*	18/20*
4.0	2.2	20/20	20/20	20/20	20/20

* signs of toxicity observed in surviving fish

Validity criteria fulfilled:

yes

Conclusions:

The LC50 (96h) of the test was 0.68 mg/L
The NOEC of the test item was 0.42 mg/L

Executive summary:

The 96h LC₅₀ of fenbuconazole to bluegill sunfish (Lepomis macrochirus) was 0.68 mg a.s./L, mean measured. The NOEC was 0.42 mg a.s./L, mean measured, based on the lack of sublethal effects at this and all lower concentrations.

Description of key information

The 96h LC₅₀ of fenbuconazole to bluegill sunfish (Lepomis macrochirus) was 0.68 mg a.s./L, mean measured.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Dose descriptor:

LC50

Effect concentration:

0.68 mg/L