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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:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
26/04/2000 - 29/06/2000
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: RA study
Justification for type of information:
Refer to the section 13 for details on the read across justification.
Reason / purpose:
read-across source
Qualifier:
according to
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Specific details on test material used for the study:
- Name of test material (as cited in study report): DL-alpha-Tocopheryl acetate
- Substance type: Vitamin derivative
- Physical state: Liquid (viscous oil)
- Storage condition of test material: At room temperature
Analytical monitoring:
yes
Details on sampling:
- Concentrations: 4.3, 9.4, 21, 45 and 100 mg/l
- Sampling method: Samples of each concentration were taken from the test solutions at the start and at the end of the exposure period. All test medium samples for the analytical determinations were taken from the approximate centre of the test vessels.
- Sample storage conditions before analysis: Not relevant, analysis was performed immediately after sampling
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: 100.0 mg of the oily, not soluble test item was mixed with about 100 ml test medium in a beaker, homogenised by Ultra Turrax T25 for 25 minutes and filled up to 1000 ml with test medium. For the preparation of the test solutions the following amounts of stock solution were added to the test vessels and then made up to 200 ml with test medium: 8.5, 19, 41, 91 and 200 ml respectively. The 200 ml of test solutions were divided up into portions of 100 ml for each replicate test vessel. Since all amounts of the stock solution were taken out from the approximate centre of the vessel, only the more stable part of the emulsion was added to the test vessels, reduced by part of the test substance adsorbed onto the glass walls and/or swimming at the surface of the water.
- Controls: Yes
- Evidence of undissolved material (e.g. precipitate, surface film, etc): Yes, after preparing the stock solutions an emulsion of fine, continuously distributed droplets remained in the test water. After an equilibration time of one hour, small oily droplets were swimming at the surface of the water.
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Daphnia magna
- Strain: Straus, clone 5
- Source: laboratories of the ecotox Center
- Age at study initiation (mean and range, SD): less than 24 hours
- Method of breeding: Cultures of Daphnia magna were bred in the laboratories of the Ecotox Center in glass vessels containing approximately 3 liter of reconstituted water (M4 medium, Elendt 1990). the water was renewed partially three times a week. Culturing was performed at 18-22 degrees Celsius and a photoperiod of 14 hours light and 10 hours dark. Three times a week the young Daphnia were seperated from the parent animals to maintain a stock of reproducing Daphnia within the same age.
- Feeding during test: No feeding during test


ACCLIMATION
- Acclimation period: 24 hours
- Acclimation conditions (same as test or not): yes, but test is in total darkness and no food is administered during the test
- Type and amount of food: The daphnia were fed with a suspension of green algae (Scenedesmus subspicatus) supplemented by a Tetramin-extract in such quantities that the food was consumed within 24 hours.
- Feeding frequency: Daily with the exception of the weekend.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Post exposure observation period:
No post exposure observation period
Hardness:
214 mg/l CaCO3
Test temperature:
20 +/- 2 degrees Celsius
pH:
7.6 - 8.0
Dissolved oxygen:
99% at the beginning of the test, 97 - 100% at the end of the test
Salinity:
Not relevant
Nominal and measured concentrations:
Nominal: 4.3, 9.4, 21, 45 and 100 mg/l
Measured (start): 1.54, 2.97, 7.73, 16.75 and 37.22 mg/l
Measured (end): 0.17, 0.38, 1.11, 1.63 and 4.02 mg/l
Details on test conditions:
TEST SYSTEM
- Test vessel:
- Type (delete if not applicable): closed
- Material, size, headspace, fill volume: Glass 250 ml beaker containing 100 ml of 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
- Culture medium different from test medium: No
- Intervals of water quality measurement: 48 hours


OTHER TEST CONDITIONS
- Adjustment of pH: No
- Photoperiod: Total darkness 24/24


EFFECT PARAMETERS MEASURED (with observation intervals if applicable): Immobilization

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2.2
- Range finding study
- Test concentrations: 0.01, 0.1, 1.0, 10 and 100 mg/l
- Results used to determine the conditions for the definitive study: Yes
Reference substance (positive control):
no
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
> 20.6 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
mobility
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Details on results:
- Behavioural abnormalities: At a nominal concentration of 9.4 mg/l, 1 Daphnid was immobilised at the end of the test. This effect was not assessed as a toxic effect of the test substance, since in the higher concentrations no immobility occurred.
- Mortality of control: 0%
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: Yes, after preparing the stock solutions an emulsion of fine, continuously distributed droplets remained in the test water. After an equilibration time of one hour, small oily droplets were swimming at the surface of the water. Concentrations measured during the test were substantially lower than nominal concentrations.
- Effect concentrations exceeding solubility of substance in test medium: Possibly, see explanation above.
Reported statistics and error estimates:
Calculations were carried using Microsoft Excel worksheets, which used an indefinte number of digits for the calculations, however within this report only the rounded values are displayed.
Validity criteria fulfilled:
yes
Conclusions:
Based on the results of the read across study, the 48 h EC0 was found to be 20.6 mg/L and the 48 h EC50 was found to be >20.6 mg/L.
Executive summary:

A study was conducted to determine the toxicity of the read across substance to Daphnia magna according to OECD Guideline 202, under GLP conditions. The test substance was not soluble in water, which lead to the appearance of oily droplets at the top of test vessels. Hence, toxicity values are based on mean measured concentrations. The oily droplets severely restricted Daphnia movement, but had no fatal effect. Validity criteria for the test were met. Based on the results of the read across study, the 48 h EC50 of the substance was determined to be >20.6 mg/L (Maetzler, 2000).

Description of key information

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
20.6 mg/L

Additional information

A study was conducted to determine the toxicity of the read across substance to Daphnia magna according to OECD Guideline 202, under GLP conditions. The test substance was not soluble in water, which lead to the appearance of oily droplets at the top of test vessels. Hence, toxicity values are based on mean measured concentrations. The oily droplets severely restricted Daphnia movement, but had no fatal effect. Validity criteria for the test were met. Based on the results of the read across study, the 48 h EC50 of the substance was determined to be >20.6 mg/L (Maetzler, 2000).