Benzyl 4-[(1-butyl-5-cyano-1,6-dihydro-2-hydroxy-4-methyl-6-oxopyridin-3-yl)azo]benzoate

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:

14 September to 28 September, 1990

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 203 (Fish, Acute Toxicity Test)

GLP compliance:

not specified

Analytical monitoring:

not specified

Vehicle:

no

Remarks:

dechlorinated tap water (sodium thiosulphate)

Details on test solutions:

- Method of preparation: direct dispersion in water with the aid of shielded propeller-stirrers

Test organisms (species):

Oncorhynchus mykiss (previous name: Salmo gairdneri)

Details on test organisms:

- Common name: Rainbow trout
- Length: 5.8 ± 0.7 cm
- Weight: 3.17 ± 1.00 g
- Loading: 0.79 g bw/l
- Supplier: Trafalgar nurseries, Sailsbury, UK
- Medication: none.
- Acclimation: not specified
- Feeding during acclimation and test: not specified

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

96 h

Post exposure observation period:

No post exposure observation period

Hardness:

Approximately 50 mg/l as CaCO3

Test temperature:

14 ± 1 °C

Nominal and measured concentrations:

Measured concentrations are not specified. Nominal concentrations are used for all evaluations.

Details on test conditions:

TEST SYSTEM
- Test vessels: 40 l
- Aeration: yes
- Media renewal: daily
- No. of organisms per vessel: 10
- No. of vessels per concentration: 2 replicates
- No. of vessels per control: 1

TEST CONCENTRATIONS
- Range finding study: yes (1.0, 10 and 100 mg/l)
- Results used to determine the conditions for the definitive study: no mortality in range finding study up to 72 hours, therefore, highest concentration used for the definitive study
- Test concentrations in definitive study: 100 mg/Ll (limit test)

Reference substance (positive control):

no

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Details on results:

The range finding study was terminated after 72 hours up to a test item concentration of 100 mg/l as sufficient data had been gathered to determine the no effect level (i.e. 100 mg/l) and allow initiation of the definitive study.

Sublethal observations / clinical signs:

Results from the range finding study.

Concentration (mg/L)	Cumulative Mortality (initial population = 3)
	24 h	48 h	72 h	96 h
control	0	0	0	-*
1.0	0	0	0	-
10	0	0	0	-
100	0	0	0	-

Results from the definitive study.

Concentration (mg/L)	Cumulative Mortality (initial population = 10)
	24 h	48 h	72 h	96 h
control	0	0	0	0
100 R1	0	0	0	0
100 R2	0	0	0	0

R1 = first replicate

R2 = second replicate

Conclusions:

The 96 hour LC50 of the test item was greater than 100 mg/l (nominal).

Executive summary:

The short-term toxicity of the test item to fish was evaluated in an experimental study according to a method comparable to OECD guideline 203 limit test. In a dose range finding study, groups of 3 fish were exposed to either 0, 1.0, 10 or 100 mg/l test item in dechlorinated tap water (sodium thiosulphate) for 72 hours, after which time no mortality was observed and the study was terminated. Based on the absence of mortality, the highest concentration of 100 mg/l test item was chosen for the definitive study.

In the definitive study, two replicate groups of 10 fish were exposed to the test item (100 mg/l) for 96 hours, as well as an additional control group of 10 fish in parallel, and checked for mortality every 24 hours. All findings are based on the nominal test item concentrations. No mortality was observed in the control or either replicate group after 96 hours, therefore, the 96 hour LC₅₀ of the test item was greater than 100 mg/l.

Description of key information

LC₅₀ (96 h, Oncorhynchus mykiss) > 100 mg/l (nominal)

Additional information

The short-term toxicity of the substance to fish was examined in a 96 hour test, run as limit test using Oncorhynchus mykiss. The concentration which leads to 50 % mortality of O. mykiss (LC₅₀) after 96 hours of exposure is greater than 100 mg/l, reported as nominal concentration due to poor water solubility.