Imidazo[5,1-f][1,2,4]triazin-4(1H)-one, 2-[2-ethoxy-5-[(4-ethyl-1-piperazinyl)sulfonyl]phenyl]-5-methyl-7-propyl-

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:

2000

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Deviations:

no

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

sampling schedule:
control: 0 and 48 h
test concentration: 0 and 48 h

Vehicle:

no

Details on test solutions:

Reconstituted water (so-called 'M4 medium', originally described in Water Research 24 (9): 1157-1167)

Test organisms (species):

Daphnia magna

Details on test organisms:

Daphnia magna STRAUS, parthenogenetic females; Strain of Bundesgesundheitsamt Berlin
A population of parthenogenetic females of synchronised age structure was maintained since more than 15 years in the test facility under constant temperature conditions (20 +/- 1°C) at a 16:8 hour light-dark photoperiod (illumination: < 1000 lux). The culture water (so-called 'M4 medium') was partly renewed once a week. The daphnia are exclusively fed with unicellular green algae (Scenedesmus subspicatus CHODAT) 'ad libitum'. Mortalities of parent daphnia during the culture period were recorded daily in a semi-quantitative way. The neonates were separated from their parent daphnia by filtration prior to the acute test.

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Hardness:

13.8°dH (=246 mg/L CaCO3)

Test temperature:

20.1°C

pH:

8.0

Dissolved oxygen:

8.5 mg/L (96.3 % saturation)

Nominal and measured concentrations:

Nominal: 2 mg/L
Measured concentration at 48 h: 2.8 mg/L

Details on test conditions:

PRETREATMENT OF THE TEST ITEM:
A stock solution was prepared to give the desired test concentration. To accelarate the solution procedure, a five fold amount of the water solubility (2mg/L) was taken to produce the stock solution (10 mg/L). The substance was weighed into 1 litre of dilution water and treated for one hour with an unltrasonic bath and afterwards stirred for 24 hours on a magnetic stirrer. Finally undissolved particles of the substance were removed by filtration.

TEST SYSTEM:
Test vessels: 50 mL glass beakers holding 10 neonates in 20 mL of test medium
Experimental design: 1 test concentration plus 1 control; 10 neonates per vessel, 2 replicates per concentration/control; no feeding during the exposure period
Photoperiod: 16 h light : 8 h dark
Temperature: mean +/- 1°C in the temperature range 18 - 22°C
Aeration: none
Test concentration: 2 mg/L nominal
Medium renewal: none

Reference substance (positive control):

no

Duration:

24 h

Dose descriptor:

EC0

Effect conc.:

>= 2 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

EC0

Effect conc.:

>= 2.8 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

The results are expressed in terms of nominal concentrations (24h) and in terms of mean measured concentrations (48h). Measured concentrations at 0 and at 48h of exposure correspond to 140% of the nominal value.

Validity criteria fulfilled:

yes

Remarks:

(- The immobilisation and other abnormalities in the controls < 10% by the end of the test. - The dissolved oxygen concentration remained above 3 mg/L throughout the exposure period.- concentration of test substance shall maintain >= 80% during test.)

Conclusions:

For the substance a 48h-EC0 of 2.8 mg/L (measured) was obtained.

Executive summary:

In order to test acute toxicity to invertebrates of the substance, Daphnia magna was exposed to the test solution of 1 nominal concentration of the test substance (2 mg/L) and blank control solution for a period of 48 h under static conditions. The method used was the EU Method C.2 (Acute Toxicity for Daphnia). Mobility and visible abnormalities were recorded at 24 and 48 h. The measured concentrations at 48 hours was 2.8 mg/L. No toxic effect and no abnormal behaviour was observed (up to the water solubility under exposure conditions). This toxicity study is classified as acceptable and satisfies the guideline requirements for the acute Daphnia study.

Description of key information

Using the EU Method C.2 (Acute Toxicity for Daphnia) a 72h-EC0 of 2.8 mg/L (measured) was determined. No toxic effect and no abnormal behaviour to Daphnia magna was observed (up to the water solubility under exposure conditions).

Additional information

In order to test acute toxicity to invertebrates of the substance, Daphnia magna was exposed to the test solution of 1 nominal concentration of the test substance (2 mg/L) and blank control solution for a period of 48 h under static conditions. The method used was the EU Method C.2 (Acute Toxicity for Daphnia). Mobility and visible abnormalities were recorded at 24 and 48 h. The measured concentrations at 48 hours was 2.8 mg/L. No toxic effect and no abnormal behaviour was observed (up to the water solubility under exposure conditions). This toxicity study is classified as acceptable and satisfies the guideline requirements for the acute Daphnia study.

The substance has been tested up to the water solubility under exposure conditions. In rage finding tests the maximum of water solubility of the substance under exposure conditions was determined to be about 2 mg/L. To achieve this concentration, the five fold amount of the substance (10mg/L) was weighed in. In the report of this study a water solubility of the substance of 7 mg/L was presented. This value has been determined within a GLP study. The medium in the respective study differs from the test medium used in the presented study concerning the daphnia toxicity.

The results of the main test as well as those of the range finding test clearly demonstrated that under exposure conditions the maximum water solubility is lower. If a substance is tested at the maximum water solubility, under exposure conditions slight fluctuations of the respective concentrations are to be expected. The observed difference between the nominal concentration of 2 mg/L and the mean measured concentration of 2.8 mg/L can be explained by this and is seen as negligible.