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Ecotoxicological information

Short-term toxicity to aquatic invertebrates

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Reference
Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Study period:
28 April 2015 – 30 April 2015
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)
GLP compliance:
yes (incl. QA statement)
Analytical monitoring:
no
Details on sampling:
not applicable
Vehicle:
no
Details on test solutions:
Elendt M4 medium was used as test medium (composition in accordance with OECD 202). At test initiation the pH-value of the control (untreated test medium) was 8.17, the dissolved oxygen concentration was 8.9 mg/L and the total hardness was 13°dH (232 mg/L as CaCO3).
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Strain: Daphnia magna Straus, Clone V
- Source: Federal Environment Agency (Umweltbundesamt in Berlin/Germany).
- Age at study initiation (mean and range, SD): Freshly hatched daphnids max. 24 hours old were used for the test.
- Method of breeding: Daphnia magna was bred as group culture (5 to 20 daphnids per litre) in Elendt M4 medium. The pH-value of the aerated water was within a range of 6.0 – 9.0. The dissolved oxygen was above 60 % saturation and the total hardness 140 - 250 mg/L (as CaCO3), corresponding to 7.8 - 14°dH. The animals were fed with single cell green algae (Desmodesmus subspicatus, former Scenedesmus subspicatus) at least three times a week.
- Feeding during test: None
- Food type: single cell green algae (Desmodesmus subspicatus, former Scenedesmus subspicatus)
- Frequency: at least three times a week.

ACCLIMATION
Not necessary because the daphnids were bred in the laboratory under the same conditions as in the test.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Post exposure observation period:
not applicable
Hardness:
13°dH (232 mg/L CaCO3)
Test temperature:
19.3 – 21.7 °C
pH:
7.99 – 8.92
Dissolved oxygen:
8.8 +/- 0.1 mg/L
Salinity:
not applicable
Nominal and measured concentrations:
0, 6.25, 12.5, 25.0, 50.0 and 100 mg/L (nominal)
Details on test conditions:
TEST SYSTEM
- Test vessel: four 100 mL glass beakers per concentration, each filled with 50 mL
- Aeration: none
- Test type: static
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: deionised water

OTHER TEST CONDITIONS
- Photoperiod: 16 hours photoperiod / 8 hours darkness daily

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2.0

RANGE FINDING TEST:
The non-GLP range finding test was conducted with the following concentrations: 0, 0.10, 1.00 and 10.0 mg/L. As no immobilisation above the allowed control immobilisation of 10 % was observed up to 10.0 mg/L, the main test concentrations were chosen to be 0, 6.25, 12.5, 25.0, 50.0 and 100 mg/L.
Reference substance (positive control):
yes
Remarks:
Potassium Dichromate
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
44.9 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
25 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Results with reference substance (positive control):
In order to check the validity of the results, the toxicity of the reference item potassium dichromate was tested at 1.0 and 2.0 mg/L with 20 test organisms per test concentration on 22 Apr 2015 around the same time period as the study with the test item.
The results indicate an EC50 (24 h) of the reference item potassium dichromate between 1.0 and 2.0 mg/L. Since the results fall within the range recommended by the guideline (OECD 202), the daphnids were suitable for the determination of the toxicological effects of the test item.

After 24 hours of exposure no immobilisation was observed in the control and up to and including 25.0 mg/L. 25 % of the daphnids were found immobile at 50.0 mg/L. 65 % of the daphnids were immobilised 100 mg/L.

After 48 hours of exposure no immobilisation was observed in the control and up to and including 25.0 mg/L. All daphnids were found immobile at 50.0 and 100 mg/L. The results are presented inTable 1 and Table 2.

Table 1:     Results after 24 h exposure (main test)

Concentration Test Item

Control

6.25

12.5

25.0

50.0

100

 

[mg/L]

 

immobilised daphnids after 24 h

Group 1

0

0

0

0

0

2

Group 2

0

0

0

0

0

2

Group 3

0

0

0

0

3

4

Group 4

0

0

0

0

2

5

Σ

0

0

0

0

5

13

%

0

0

0

0

25

65

Table 2:     Results after 48 hexposure (main test)

Concentration Test Item

Control

6.25

12.5

25.0

50.0

100

 

[mg/L]

 

immobilised daphnids after 48 h

Group 1

0

0

0

0

5

5

Group 2

0

0

0

0

5

5

Group 3

0

0

0

0

5

5

Group 4

0

0

0

0

5

5

Σ

0

0

0

0

20

20

%

0

0

0

0

100

100

Validity criteria fulfilled:
yes
Conclusions:
According to the results of the test, the EC50 (48 h) for N-Isobutyryl-thiourea was determined to be 44.9 mg/L (nominal). The corresponding NOEC (48 h) was 25.0 mg/L (nominal).
Executive summary:

The toxicity of N-Isobutyryl-thiourea on Daphnia magna was tested in a 48 hour acute immobilisation test. The test was performed static according to OECD Guideline 202 ("Daphnia sp., Acute Immobilisation Test") with concentrations of 0, 6.25, 12.5, 25.0, 50.0 and 100 mg/L and twenty organisms per test concentration (4 replicates of 5 animals each) were used.

According to the results of the test, the EC50 (48 h) for immobilisation was determined to be 44.9 mg/L. The corresponding NOEC (48 h) was 25.0 mg/L.

Description of key information

According to the results of the test, the EC50 (48 h) for N-Isobutyryl-thiourea was determined to be 44.9 mg/L. The corresponding NOEC (48 h) was 25.0 mg/L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates
Dose descriptor:
EC50
Effect concentration:
44.9 mg/L

Additional information

The toxicity of N-Isobutyryl-thiourea on Daphnia magna was tested in a 48 hour acute immobilisation test. The test was performed static according to OECD Guideline 202 ("Daphnia sp., Acute Immobilisation Test") with concentrations of 0, 6.25, 12.5, 25.0, 50.0 and 100 mg/L and twenty organisms per test concentration (4 replicates of 5 animals each) were used.

According to the results of the test, the EC50 (48 h) for immobilisation was determined to be 44.9 mg/L. The corresponding NOEC (48 h) was 25.0 mg/L.