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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:
April - June 2018
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:
yes
Details on sampling:
Analytical samples were taken from all test item concentrations and control at test start and after 48 hours from aged solutions. For each sampling also a retain sample was taken. 0.5 mL samples were taken and stabilized with 0.5 mL acetonitrile.
All samples were stored deep frozen until they were transferred to the analytical laboratory.
Vehicle:
yes
Remarks:
test medium
Details on test solutions:
The necessary amount of test item for preparing the stock solution was weighed on a weighing scoop and transferred to a volumetric flask. Test medium was added up to the bench mark and the solution was homogenised by shaking. Afterwards the solution was clear and transparent and foaming was observed. Lower test solutions were prepared by dilution of the appropriate solution with test medium. Foaming was also observed for the first dilution. ~ 50 mL of the prepared solutions were transferred to each test vessel.
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Daphnia magna Straus
- Strain/clone: Clone V
- Source: Federal Environment Agency in Berlin/Germany
- Feeding during test: None

Feeding duringbreeding: single cell green algae (Desmodesmus subspicatus) at least three times a week

The daphnids were reared at a temperature of 20 ± 2 °C in a climatic chamber with 16 hours of illumination and 8 hours of darkness. The medium was changed three times per week. A pipette was used to separate the young daphnids from the adults.
Freshly hatched daphnids less than 24 hours old were used for the test.

Daphnia magna was bred as single culture (1 daphnid per 100 mL) 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.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Post exposure observation period:
N/A
Hardness:
13°dH (232 mg/L as CaCO3)
Test temperature:
19.6 – 21.8 °C
pH:
7.85 – 8.04
Dissolved oxygen:
above 60 % saturation
Salinity:
N/A
Conductivity:
not specified
Nominal and measured concentrations:
The following nominal concentrations were tested in the main test: 111.1, 50.5, 23.0, 10.4, 4.74 mg/L (water content included), corresponding to 100, 45.5, 20.7, 9.36, 4.27 mg/L (water content excluded) and control.

The measured content of test item was between 92 % and 108 % of nominal in the fresh samples with a mean initial concentration of 98 % of nominal. In the aged samples the measured content was between 92 % and 108 % of nominal with a mean measured concentration of 100 % of nominal. Since the content of active ingredient in the samples was between 80 and 120 % of nominal the toxicological endpoints were evaluated using nominal concentrations.
Details on test conditions:
TEST SYSTEM
- Test vessel: four 100 mL glass beakers per treatment, each filled with ~ 50 mL, one additional replicate for physico - chemical measurements without test organisms
- Loading: ~ 10 mL of test solution for each animal
- Aeration: none
- Type of flow-through (e.g. peristaltic or proportional diluter):
- Renewal rate of test solution (frequency/flow rate):
- No. of organisms: 20 per treatment in 4 replicates of 5
- No. of replicates: 4

TEST MEDIUM / WATER PARAMETERS
Elendt M4 test medium

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

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
After 24 h and 48 h the immobilised daphnids were counted. All daphnids not able to swim within 15 seconds after gentle agitation of the test vessel were considered to be immobilised. If present, behavioural changes of daphnids were recorded at 24 and 48 hours after starting the test.

VEHICLE CONTROL PERFORMED: yes
Reference substance (positive control):
yes
Remarks:
potassium dichromate (1.00 mg/L, 2.00 mg/L)
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
14 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Remarks:
based on purity 90%
Basis for effect:
mobility
Key result
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
9.4 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Remarks:
based on purity 90%
Basis for effect:
mobility
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
15.5 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat. (total fraction)
Basis for effect:
mobility
Key result
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
10.4 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat. (total fraction)
Basis for effect:
mobility
Details on results:
After 24 hours of exposure no immobilisation was observed in the control and up to and including 10.4 mg/L. 65 % immobilisation was observed at 23.0 and 50.5 mg/L. At the highest test item concentration of 111.1 mg/L, 85 % of the daphnids were immobile.
After 48 hours of exposure no immobilisation was observed in the control and 4.74 mg/L. No immobilisation higher than the allowed control immobilisation was observed at 10.4 mg/L. 95 % immobilisation was observed at 23.0 mg/L. At 50.5 mg/L and the highest test item concentration of 111.1 mg/L all daphnids were immobile.
After 24 hours the mobile daphnids in the highest test item concentration of 111.1 mg/L were swimming in circles and showed jerky swimming behaviour.
Results with reference substance (positive control):
The results indicate an EC50 (24 h) of the reference item potassium dichromate between 1.00 and 2.00 mg/L. Since the results are in accordance with the requirements of the OECD guideline 202 and fall within the historical data generated with the reference item at the testing facility, the daphnids were suitable for the determination of the toxicological effects of the test item.
Reported statistics and error estimates:
The 24 h and 48 h EC50 are the calculated concentrations where 50 % of the daphnids were immobilised after 24 and 48 hours, respectively.
The values for EC50 were determined by Probit analysis using linear max. likelihood regression. The evaluation of data was performed by ToxRat Professional 3.2.1.
The NOEC was established based on the highest concentration at which the immobilisation is not higher than the allowed control immobilisation (≤ 10 % immobilisation).
Validity criteria fulfilled:
yes
Remarks:
The control immobilisation was 0 %. The dissolved oxygen concentration at the end of the test was ≥ 8.0 mg/L.
Conclusions:
According to the results of the test, the EC50 (48 h) for immobilisation was determined to be 14 mg/L (nominal, active ingredient). The corresponding NOEC (48 h) was 9.4 mg/L (nominal, active ingredient).
Executive summary:

According to the results of the test, the EC50(48 h) for immobilisation was determined to be 14 mg/L (nominal). The corresponding NOEC(48 h) was 9.4 mg/L (nominal).

Description of key information

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates
Effect concentration:
14 mg/L

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