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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:
2003-01-06 to 2003-01-09
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP guideline study
Qualifier:
according to
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Analytical monitoring:
no
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: The test item is not well soluble in test water. To avoid physical effects of undissolved test item on Daphnia only dissolved test item was tested by using a filtrate of a supersaturated stock suspension. Therefore, at two times, supersaturated stock suspensions of nominal 100 mg test itemIL were prepared by suspending 50 mg test item in 500 mL test water. The suspensions were ultrasonic treated for 30 minutes and stirred for 24 hours each, to dissolve as much test item as possible. Then, the stock suspensions were filtered through a cellulose-nitrate filter (pore size 0.45 fim). The test media were renewed after 24 hours.
- Controls: test water without addition of the test item.
- Evidence of undissolved material (e.g. precipitate, surface film, etc): no, suspension was filtered
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Water flea
- Strain: Daphnia magna (Straus), clone 5
- Sex: female
- Source: Umweltbundesamt, Institut for Wasser-, Boden- und Lufthygiene, Berlin, Germany
- Age at study initiation (mean and range, SD): 6 - 21.5 hours
- Method of breeding: The Daphnia were bred in the laboratories of IBACON under similar temperature and light conditions as in the test, and in reconstituted water of a similar quality regarding to pH, components of the main ions and total hardness as the test water used in the test (see below). The test organisms were not first brood progeny. The Daphnia of the stock culture were fed at least each working day with green algae (Desmodesmus subspicatus) freshly grown in the laboratories of IBACON.
- Feeding during test: none


ACCLIMATION
- Acclimation period: 6 hours
- Acclimation conditions: same as test
- Type and amount of food: not fed
- Health during acclimation (any mortality observed): not mentioned
Test type:
semi-static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
48 h
Hardness:
2.5 mmol/L (= 250.0 mg/L) as CaCO3
Test temperature:
20 - 21 °C
pH:
7.8 - 7.9
Dissolved oxygen:
at least 6.6 mgIL or higher
Salinity:
In deionized water (conductivity < 5 µS/cm) analytical grade salts were added to following nominal concentrations:
2.0 mmol/L (= 294 mg/L) CaCl2 x 2 H2O
0.5 mmol/L (= 123 mg/L) MgSO4 x 7 H2O
0.75 mmol/L (= 65.0 mg/L= NaHCO3
0.075 mmol/L =(= 5.8 mg/L) KCl
Nominal and measured concentrations:
WAF, no analytical determination of test substance concentration
Details on test conditions:
TEST SYSTEM
- Test vessel: Glass beakers of 250 mL volume with 150 mL test medium
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 2


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: reconstituted water
- Alkalinity: 0.8 mmol/L
- Ca/mg ratio: 4:1 (based on molarity)


OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 16 h light; 8 h dark
- Light intensity: 480 lux


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Immobility or mortalitiy of the Daphnia was determined by visual controls after 24 and 48 hours. Measurement of pH, dissolved oxygen and water temperature at test start and end of test. The behaviour of the test substance in test water was determined at the start of the test, after 24 and 48 hours.


TEST CONCENTRATIONS
- Range finding study: Pre-experiments were carried out to determine the solubility of the test item in test water. These pre-experiments to the solubility of the test item were not performed in compliance with GLP-Regulations, but the raw data of these pre-experiments will be archived under the project number of the present study.
The test concentrations were based on the results of a range-finding test. However, no concentrations in excess of the solubility limit of the test item in test water were tested.
- Test concentrations: 100 mg/L limit test
Reference substance (positive control):
no
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Basis for effect:
mobility

Table: Influence of test substance on the mobility of Daphnia magna

Treatment  No. of Daphnia tested  No. of immobilized Daphnia after         % of immobilized Daphnia after
    24 h   48 h  24 h  48 h
control   20  0  0  0  0
 filtrate of test substance  20  0  0  0  0
Validity criteria fulfilled:
yes
Remarks:
Mortality of Daphnia magna in the control did not exceed 10 % and no Daphnia were trapped at the water surface
Conclusions:
Due to low water solubility of the test substance a filtrate of a supersaturated stock suspension of nominal 100 mg/L was tested. Thus no concentrations above the solubility limit of the test substance in the used test water were tested. Due to the low water solubility limit no analytical dose verfication could be done in the present test. The 48-hour NOEC, respectively the 48-hour EC0 of the test substance to Daphnia magna were determined to be at least up to the solubility limit. The NOEC and the EC0 might even be higher, but concentrations in excess of the solubility limit had not been tested. The 48-hour EC50 was clearly higher than the solubility limit of the test substance in the used test water.
Executive summary:

Due to the low water solubility limit of the test item a filtrate of a supersaturated stock suspension of nominal 100 mgIL was tested. Thus, no concentrations above the solubility limit of the test item in the used test water were tested. Additionally, a control was tested in parallel. The 48-hour EC 0 of 2 -decyltetradecanoic acid to Daphnia magna was determined to be at least up to the solubility limit of the test item in test water. The EC 0 might even be higher than this concentration, but concentrations in excess of the solubility limit have not been tested. The 48-hour EC 50 and EC 100 were clearly higher than the solubility limit. These values could not be quantified due to the absence of toxicity of 2 -decyltetradecanoic acid up to the highest test concentration which could be dissolved in test water.

Description of key information

For investigation of the acute toxicity of 2 -decyltetradecanoic acid an acute daphnia test according to OECD 202 was conducted. The EC50 (48 h) was > 100 mg/L. Due to low water solubility of the test substance a filtrate of a supersaturated stock suspension of nominal 100 mg/L was tested. The 48-hour EC50 was clearly higher than the solubility limit of the test substance in the used test water.

Key value for chemical safety assessment

Additional information