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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
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP guideline study with analytical monitoring info on test substance
Qualifier:
according to guideline
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Remarks:
Landesamt für Umwelt, Wasserwirtschaft und Gewerbeaufsicht, 2009
Analytical monitoring:
yes
Details on sampling:
- Sampling method: Samples for concentration control analysis were taken from each freshly prepared solution (0 h and 24 h) from additionally prepared test vessels without daphnids and at the end of each exposure interval (after approx. 24 h and 48 h) from all test vessels with mobile daphnids and the lowest concentration with 100% immobilisation.
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Water accommodated fraction (WAF) of the test substance were prepared according to OECD 23. Fresh test solutions were prepared at 0 and 24 hours. The test substance was homogenized by shaking the container before removal for weighing. The stock solutions were prepared by weighing the test substance on a glass coverslip then adding this to 1L of test medium in a 2 L glass flask. The stock solutions were shaken for approximately 10 min at 20 ± 2 °C.
- Differential loading: yes
- Evidence of undissolved material (e.g. precipitate, surface film, etc): The test groups 22 - 100 mg/L appeared turbid after preparation. Since the test substance was homogenously dispersed in the test medium, no attempt was made to separate any potentially undissolved components. The daphnids were exposed to the entire loaded mass of test substance.
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Daphnia magna STRAUS
- Source: Daphnia magna STRAUS was originally supplied from "Institut National de Recherche Chimique Appliquée, France", and has been breeded from 1978 in the Laboratories of BASF.
- Age at study initiation (mean and range, SD): <24 hours old
- Food type: Unicellular algae Desmodesmus subspicatus, cultured continuously at the test facility
- Frequency: Daily
- Photoperiod: 16 hours light, 8 hours dark
- Culture media: synthetic fresh water (Elendt M4) prepared according to OECD 202
- Renewal of the culture water: Twice weekly
Test type:
semi-static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Hardness:
2.2 - 3.2 mmol/L (total hardness)
Test temperature:
19.5 - 20.0 °C
pH:
7.5 - 8.5
Dissolved oxygen:
> 3 mg/L (8.4 - 9.2 mg/L)
Nominal and measured concentrations:
Nominal (loading rate): 4.6, 10, 22, 46 and 100 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: Glass beakers (nominal volume 100 mL), test volume 50 mL. All test vessels were saturated for at least 24-h before use with solution to reduce the possibility of test substance loss during the test by adsorption to the test vessel. This solution was discarded and fresh test solution was used to start the test.
- 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: according to guideline: M4 medium with the properties:
Total hardness: 2.20 - 3.20 mmol/L
Alkalinity up to pH 4.3: 0.8 - 1.0 mmol/L
Ratio Ca/Mg ions: about 4:1
pH value: 7.5 - 8.5
Conductivity: 550 - 650 microS/cm

OTHER TEST CONDITIONS
- Photoperiod: 16:8 hours, diffuse light (about 172 - 654 lux at a wave length of 400-750 nm)

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
Observations: mobile daphnids after 24 and 48 h
Measurements: Temperature, pH and oxygen content after 0, 24 and 48 h

TEST CONCENTRATIONS
Nominal test concentrations: 4.6, 10, 22, 46 and 100 mg/l. A control was tested in parallel.
Reference substance (positive control):
yes
Remarks:
potassium dichromate (K2Cr2O7)
Duration:
24 h
Dose descriptor:
EL50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
EL50
Effect conc.:
36.3 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: 27.4 - 49.6 mg/L
Duration:
24 h
Dose descriptor:
EL0
Effect conc.:
22 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
EL0
Effect conc.:
4.6 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Details on results:
- Mortality of control: no
- Effects: After 24 h effects could be observe at 46 mg/L (one daphnid was immobilized) and 100 mg/L (two daphnids were immobilized). After 48 h one daphnid was immobilized at 10 mg/L and 8 daphnids at 22 mg/L. The maximum amount of daphnids (18 daphnids) were immobilized at 100 mg/L.
- Effect concentrations exceeding solubility of substance in test medium: The test groups 22 - 100 mg/L appeared turbid after preparation. The daphnids at concentrations 46 and 100 mg/L were covered with test substance at the end of exposure (48h).
Results with reference substance (positive control):
Tests with a reference substance, potassium dichromate (K2Cr2O7), are conducted monthly. Reference substance tests are conducted according to OECD 202 guidelines and in accordance with GLP, but without a GLP status.
The EC50(24h) of the reference substance potassium dichromate was 1.10 mg/L. Date of the last control experiment: 15 Mar 2010, project number: 50E0063/043039.
Validity criteria fulfilled:
yes
Remarks:
≤ 10% mortality in the control and O2 concentration > 3 mg/L in the control and test vessels
Conclusions:
The 48 hour EC50 values for ASA in this acute toxicity study with Daphnia magna was 36.3 mg/L based on the loading rate of the test substance.
Executive summary:

In a test performed according to OECD 202, Daphnia magna were exposed to the nominal loading rates of 4.6, 10, 22, 46 and 100 mg/L test substance in 4 replicates of each 5 animals. Although at high concentrations the water solubility seemed to be exceeded, the EC50(48 h) was estimated to be 36.6 mg/L based on observed immobilization at lower concentrations.

Description of key information

Short-term toxicity: EC50 (48 h) = 36 mg/L (OECD 202)

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates
Effect concentration:
36.6 mg/L

Additional information

In a test performed according to OECD 202, Daphnia magna were exposed to the nominal loading rates of 4.6, 10, 22, 46 and 100 mg/L test substance in 4 replicates of each 5 animals. Although at high concentrations the water solubility seemed to be exceeded, the EC50(48 h) was estimated to be 36.6 mg/L based on observed immobilization at lower concentrations.