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Short-term toxicity to aquatic invertebrates

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short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Study period:
15 Mar - 14 May 2016
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
according to guideline
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Version / remarks:
according to guideline
EU Method C.2 (Acute Toxicity for Daphnia)
GLP compliance:
yes (incl. QA statement)
Federal Office for the Environment (FOEN)
Analytical monitoring:
Details on sampling:
- Concentrations: samples of the concentrations of 4.6 to 46 mg/L were not analyzed since these concentrations were below the 48 h NOEC and, thus, were not relevant for the interpretation of the biological results
- Sampling method: duplicate samples were taken from each treatment at the start and at the end of the test for measurement of the test item concentrations. After 48 h the contents of the respective replicates were combined prior to sampling.
- Sample storage conditions before analysis: after sampling, samples were stabilized with acetonitrile (1 mL acetonitrile per 10 mL sample volume) and deep-frozen (at about -20 °C) (method based on pre-experiments)
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: a 100 mg/L solution was prepared by dissolving the test item in 1 L test water using intense stirring for 10 min at room temperature. This test concentration was further diluted with test water to prepare the remaining test concentrations
Test organisms (species):
Daphnia magna
Details on test organisms:
- Common name: water flea
- Source: bred in the laboratory
- Age of test organisms at test start: 6-24 h old - no first brood progeny
Test type:
Water media type:
Limit test:
Total exposure duration:
48 h
Test temperature:
21 °C
7.4 - 7.9
Dissolved oxygen:
8.3 mg/L
Nominal and measured concentrations:
Nominal test concentrations: 4.6, 10, 22, 46 and 100 mg/L
measured (0 h fresh): 84.9 mg/L (nominal 100 mg/L)
measured (48 h aged): 35.8 mg/L (nominal 100 mg/L)
Details on test conditions:
- Test vessel: 100-mL glass beakers (vessels were covered with transparent disposable polypropylene sheets)
- Fill volume: 50 mL
- Aeration: test water was aerated prior to the start of the study until oxygen saturation was reached
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

- Source/preparation of dilution water: according to ISO 6341
- Ca/Mg ratio: 4:1
- Intervals of water quality measurement: pH, dissolved oxygen concentrations, water temperature and appearance of the test media were determined in each treatment at the start and end of the test

- Photoperiod: 16 h light to 8 h dark cycle with a 30 min transition period
- Light intensity: 15 - 18 μmol m^-2 s^-1

EFFECT PARAMETERS MEASURED (with observation intervals if applicable): immobility of daphnids was determined by visual inspection after 24 and 48 h

- Test concentrations: 1, 10, 100 mg/L
- Results used to determine the conditions for the definitive study: yes, no immobilization observed during an exposure time of 48 h
Reference substance (positive control):
potassium dichromate
Key result
48 h
Dose descriptor:
Effect conc.:
> 55 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
Details on results:
- Mortality of control: no
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: no
Results with reference substance (positive control):
EC50 (24 h): 1.6 mg/L
Reported statistics and error estimates:
The 24-hour and 48-hour EC50 could not be calculated due to the absence of toxicity of the test item and was, therefore, determined directly from the raw data.
The biological results were related to the mean measured test item concentration of 55 mg/L.

Table 1: The 24 h and 48 h EC Values.

EC Values (0-48 h) Immobility
Mean measured concentration [mg/L]
24-hour EC50  >55
24-hour EC0  55
24-hour EC100  >55
48-hour EC50  >55
48-hour EC0 and 48-hour NOEC 55
48-hour EC100 >55

Analytical results:

The % nominal found in the freshly prepared test sample was 85% (day 0). The % nominals found in the test sample taken from the aged test media was 36%.

Table 2: Analytical results.

Day [d]
Test Item [mg/L]
of Test Item [mg/L]
% of Nominal
0 fresh control n.d n.a.
100 77.2 85
2 aged control n.d. n.a.
100 32.5 36
Validity criteria fulfilled:
The test item had no acute toxic effects on Daphnia magna in a static 48-hour test (OECD 202) up to the mean measured concentration of 55 mg/L under the conditions of the test.

Description of key information

This study resulted in an EC50 (48 h) of > 55 mg/L (mean measured) based on mobility of Daphina magna (OECD 202, GLP).

No toxicity was observed for aquatic invertebrates up to the tested concentration.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates
Effect concentration:
55 mg/L

Additional information

One experimental study is available investigating the short-term effects of the substance to aquatic invertebrates. The study was performed under static conditions according to OECD 202 (GLP) with the water flea Daphnia magna. The test organism was exposed to 4.6, 10, 22, 46 and 100 mg/L test concentrations for 48 h. The 100 mg/L test concentration was monitored by HPLC/UV at the beginning and at the end of the exposure period. 85% of the test item was recovered at test start while only 36% of the nominal value was found after 48 h. Water samples of the remaining concentrations (4.6 to 46 mg/L) were below the 48-h NOEC and where therefore not measured. The biological results were related to the mean measured test item concentration of 55 mg/L. No toxic effects on D. magna were observed after 48 h resulting in an EC50 > 55 mg/L based on the mean measured concentration.