diethyl 1-(2,4-dichlorophenyl)-5-methyl-4,5-dihydro-1H-pyrazole-3,5-dicarboxylate

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:

20 Mar 1996 - 06 Mar 1997

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Principles of method if other than guideline:

and US-EPA Pesticides Assessment Guidelines; Subdivision E §72-2 under GLP.

GLP compliance:

yes

Analytical monitoring:

yes

Vehicle:

yes

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)

- Method: Test water, solvent (0.1 ml acetone/L) and the defined amount of test substance were added into a volumetric flask, stirred with a dissolver (Ultra Turrax) and transferred into the test vessels. The test substance partially precipitated as an orange-brown precipitate at the bottom of the test vessels and at the water surface. An ultra turrax was used to facilitate solution of the test substance.To prevent precipitation during preparation of medium, the chemicals were added into 500-800 ml deionized water and then filled up to 100 ml.

- Chemical name of vehicle: Acetone of analytical grade quality (lot: 60850, Riedel-de Haen, D-30926 Seelze, FRG) was used as solvent with a maximum of 0.1 ml per liter test water.

- Evidence of undissolved material : The test substance was not completely soluble in the test water. It precipitated at the bottom of
the test vessels and appeared at the water surface in all test concentrations.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Waterflea
- Strain: Daphnia magna STRAUS
- Source: The daphnids used in this test were bred in the animal maintenance room of the Oekobiologie of Hoechst Schering AgrEvo GmbH, Umweltforschung, (Environmental Sciences, Ecobiology).
- Age at study initiation: < 24 h
- Method of breeding: They were cultured in beakers (19x13 cm, approximate dimensions of internal height and diameter), containing initially 20
adult animals in 2 litre test water. Approximately twice a month the daphnids were transferred into fresh water resulting in the initial biological loading. The Daphnia cultures were maintained at 20 ± 2°Celsius and a photoperiod of 16 hours light, 8 hours dark. All cultures were fed with unicellular green algae (Scenedesmus subspicatus CHODAT, strain 86.81 SAG) twice a week.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

1.63 mmol/L (Ca2+ + Mg2+)

Test temperature:

19.4± 0.2 °C

pH:

7.7 ± 0.1

Dissolved oxygen:

9.3 ± 0.2 mg/L

Salinity:

-

Nominal and measured concentrations:

Nominal concentrations of 0 (negative control), 0 (solvent control, 0.1 mL acetone/L), 10, 18, 32, 56, 100, and 180 mg/L test item
The mean measured concentrations of the dissolved test item over the 48-hour study period were 4.2, 5.1, 7.8, 13.2, 15.3 and 16.9 mg/L.

Details on test conditions:

TEST SYSTEM
- Test vessel:
- Material, fill volume: 600 ml glass jars, containing 200 ml of test water, covered with glass lids during the test.
- Aeration: no
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 2
- No. of vessels per vehicle control (replicates): 2


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Test water was an artificial mineral medium M4 (Elendt 1990), slightly modified.
- Culture medium different from test medium: no
- Intervals of water quality measurement: The analyses of total hardness, acid binding capacity, and nitrite content were made
by the Umweltforschung, Oekobiologie during the first test day. The temperature of the water bath was recorded continuously during the whole test
period in a separate vessel. Dissolved oxygen, pH, water temperature and conductivity were determined initially and at the end of testing in one jar per concentration and in the control groups.


OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: light dark cycle 16L/8D
- Light intensity: illuminated by wide spectrum fluorescent lights


EFFECT PARAMETERS MEASURED : The daphnids were examined daily for signs of intoxication and mortality.

Reference substance (positive control):

not specified

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

5.9 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

4.2 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

mobility

No mortality or clinical signs of intoxication were observed in both control groups and at

4.2 mg/L test item. Incipient (20%) mortality was observed at 5.1 mg/L after 48 hours. Higher test

concentrations caused almost complete mortality after 48 hours. Therefore, the NOEC after 24h and 48h

exposure was 5.1 and 4.2 mg/L test item, respectively. The 24-hr and 48-hr EC50 was calculated to be 9.4 and

5.9 mg/L AE F107892, respectively.

Conclusion:

Based on measured concentrations, the 48-hour LC50 in Daphnia magna was 5.9 mg /L test item. The NOEC

was 4.2 mg /L test item due to incipient mortality at 5.1 mg/L test item.

Description of key information

EC50 (48 h) = 5.9 mg/L with Daphnia magna (measured, OECD 202)

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

5.9 mg/L

Additional information

One key study on the parent substance on the acute toxicity of the substance to aquatic invertebrates is available. The study investigated the acute toxicity on Daphnia magna according to OECD 202 (GLP) under static conditions. The key study on the parent substance was conducted as a static test with test concentrations ranging from 10 – 180 mg/L (1997a). Based on measured concentrations, the 48-hour EC50 in the key study was determined to be 5.9 mg /L test item.

Supporting information on the toxicity of three different metabolites of the test item is available. All available studies were conducted according to OECD 202 (GLP) with Daphnia magna as test organism.

A supporting study on the actue toxicity of a metabolite determined an EC50 (48 h) > 60.3 mg/L based on measured concentrations (1997b).

Two additional studies on two further metabolites of the parent substance determined an EC50 (48 h) > 100 mg/L nominal (1999, 2002).