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Ecotoxicological information

Short-term toxicity to aquatic invertebrates

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Link to relevant study record(s)

Reference
Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2002-07-02 to 2002-07-04
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)
Version / remarks:
4th April 1984
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method C.2 (Acute Toxicity for Daphnia)
Version / remarks:
31st July 1992
Deviations:
no
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
- Concentrations: A sample of 5 mL was taken from the 1000 mg/L solution container at the beginning of the test. Samples totaling 5 mL were also
- Sample storage conditions before analysis: stored at 20 °C
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: Each test solution was prepared by stirring the test item in M4 reconstituted water at the appropriate loading rate for 24 hours. After a filtration through a filter of porosity 0.45 µm, the WSF was collected and used as the test solution.
- Eluate: water
- Differential loading: the animals are loaded at one animal/20 mL of culture water during culture; the animals are loaded at one animal for 10 mL of solution during the test
- Controls: yes (water)
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Daphnia magna STRAUS
- Strain: clone 5
- Source: Centre Technique du Bois et de l`Ameublement; Paris; Farnce
- Age at study initiation : between 6 and 24 hours old
- Feeding during test: Animals were not fed during the test.

ACCLIMATION
- Acclimation period: animals are held in water of the same quality as the test water from birth until use in the test
- Acclimation conditions: the same conditions that were used in the test
- Type and amount of food: between 0.1 and 0.2 mg of carbon per Daphnia per day (in from of algal strain Scenedesmus subspicatus)
- Feeding frequency: daily
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
48 h
Hardness:
between 238 and 289 mg/L (as CaCO3)
Test temperature:
between 19.1 °C and 20 °C
pH:
7.67 to 8.51
Dissolved oxygen:
8.3 and 10.0 mg/L (> 60% of the air saturation value)
Nominal and measured concentrations:
- nominal concentration: 0, 1, 10, 100, 1000 mg/L
- measured initial concentration (1000 mg/L): 0.598 mg/L (The test item is not stable under the experimental conditions since its concentration fell below 80 % of the initial value during the test.)
Details on test conditions:
TEST SYSTEM
- Aeration: was not used during the test. Dilution water was areated prior to the addition of the test item.
- 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: reconstituted (M4)
- Ca/Mg ratio: 4:1
- Conductivity: < 10 µS/cm
- Intervals of water quality measurement: The pH and dissolved oxygen values of the control and the highest loading rate were measured at the beginning and the end of the test. Temperature was measured at the beginning of the test and the maximum and mimimum temperatures during the test recorded. Water hardness was checked at the beginning and the end of the test in the control solution.

OTHER TEST CONDITIONS
- Photoperiod: light: 16 hours and dark: 8 hours

EFFECT PARAMETERS MEASURED:
Observations were carried out at 0, 24 and 48 hours in order to determine the number of immobilized daphnids in each test solution. Immobilization is defined as the inability of a daphnid to swim within 15 seconds after gentle agitation of the test vessel.

TEST CONCENTRATIONS
- Range finding study: The range-finding test was undertaken using 20 daphnids (in four replicates of five) per loading rate using the following nominal loading rates: 1, 10 and 100 mg/L.
Reference substance (positive control):
no
Key result
Duration:
48 h
Dose descriptor:
EL50
Effect conc.:
> 1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: corresponding to 0.598 mg/L expressed as actual concentration
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
> 0.598 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: corresponding to 0.598 mg/L expressed as actual concentration
Details on results:
- No difficulty was experienced in discerning the daphnids during the observation periods.
- Limit test: After 48 hours, immobilizations were 0 % in the control and the limit test solution (1000 mg/L nominal).
- Range-finding test: No immobilization was observed at 0, 1, 10, 100 and 1000 mg/L nominal throughout the test.
- As the test item was not found to be toxic at the nominal loading rate of 1000 mg/L, chemical analysis was undertaken to measure the concentration of the test item, based on the peroxide measurement, in this solution. The measured concentration was 0.0415 mg/L after 24 hours, corresponding to 7 % of the initial concentration, and < 0.0394 mg/L (limit of quantification) after 48 hours. The measured concentration of the test item in the limit test solution at the beginning of the test (0.598 mg/L) was retained for data interpretation since a geometric mean of measured concentrations throughout the test could not be determined.
Reported statistics and error estimates:
Determination of the EL50: When for at least two loading rates, immobilization is > 0 % and < 100 %, the EL50 is calculated according to Probit analysis. The confidence interval limits are calculated statistically according to Fieller`s method. When at only one loading rate, immobilization is > 0 % and < 100 %, the EL50 is also calculated by Probit analysis. In this case, the highest loading rate causing no immobilization and the lowest loading rate producing 100 % immobilization are used as confidence limits. If at all loading rates, immobilization is 0 % or 100 %, the EL50 corresponds to the geometric mean of the highest loading rate causing no immobilization and the lowest loading rate producing 100 % immobilization.
Validity criteria fulfilled:
yes
Conclusions:
The 48-hour EC50 of cyclohexylidenebis[tert-butyl] peroxide in a static test system is > 1000 mg/L expressed as initial loading rate (EL50), corresponding to 0.598 mg/L expressed as actual concentration (measured concentration at the beginning of the test in the saturated solution obtained from the loading rate 1000 mg/L) for Daphnia magna.
Executive summary:

The acute toxicity of cyclohexylidenebis[tert-butyl] peroxide was evaluted in the Cladoceran Daphnia magna Straus (clone 5) using a 48 -hour static test according to OECD guideline No. 202 and EU method C.2. The study included a limit test and a range-finding test. In the limit test, twenty daphnids (in four replicates of five) were exposed to a nominal loading rate of 1000 mg/L for 48 hours while a second group of 20 daphnids (in four replicates of five) was exposed to test dilution water (M4) only (control solution).

In the range-finding test, three groups of 20 daphnids (in four replicates of five) were subjected to nominal loading rates of 1, 10, 100 and 1000 mg/L for a period of 48 hours. The solutions remained unchanged for the duration of the test. Immobilization at each loading rate was recorded at 0, 24 and 48 hours. Chemical analysis was undertaken to measure the concentration of the test item, based on the peroxide, in limit test solution (loading rate of 1000 mg/L) throughout the test. In the limit test, immobilizations were 0 % in the control and the limit test solution (1000 mg/L nominal) after 48 hours.

In the range-finding test, no immobilization was observed at 1, 10,100 and 1000 mg/L nominal throughout the test. As the test item was not found to be toxic at the nominal loading rate of 1000 mg/L (limit test solution), chemical analysis was undertaken to measure the concentration of cyclohexylidenebis[tert-butyl] peroxide in this solution. The initial concentration of the test item measured in the limit test solution was 0.598 mg/L. The test item was not stable under the experimental conditions since its concentration fell below 80 % of the initial value during the test. The measured concentration was 0.0415 mg/L after 24 hours, corresponding to 7% of the initial concentration, and < 0.0394 mg/L (limit of quantification) after 48 hours. The measured concentration of the test item in the limit test solution at the beginning of the test (0.598 mg/L) was retained for data interpretation since a geometric mean of measured concentrations throughout the test could not be determined.

Hence, the highest concentration resulting in no immobilization at 48 hours was >= 1000 mg/L expressed as initial loading rate, corresponding to 0.598 mg/L expressed as actual concentration. The 48-hour EC50 of cyclohexylidenebis[tert-butyl] peroxide in a static test system is > 1000 mg/L expressed as initial loading rate (EL50), corresponding to 0.598 mg/L expressed as actual concentration (measured concentration at the beginning of the test in the saturated solution obtained from this loading rate of 1000 mg/L) for Daphnia magna.

Description of key information

The 48-hour EC50 of cyclohexylidenebis[tert-butyl] peroxide in a static test system is > 1000 mg/L expressed as initial loading rate (EL50), corresponding to 0.598 mg/L expressed as actual concentration (measured concentration at the beginning of the test in the saturated solution obtained from the loading rate 1000 mg/L) for Daphnia magna.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates
Dose descriptor:
EC50
Effect concentration:
> 0.598 mg/L

Additional information

The acute toxicity of cyclohexylidenebis[tert-butyl] peroxide was evaluted in the Cladoceran Daphnia magna Straus (clone 5) using a 48 -hour static test according to OECD guideline No. 202 and EU method C.2. The study included a limit test and a range-finding test. In the limit test, twenty daphnids (in four replicates of five) were exposed to a nominal loading rate of 1000 mg/L for 48 hours while a second group of 20 daphnids (in four replicates of five) was exposed to test dilution water (M4) only (control solution).

In the range-finding test, three groups of 20 daphnids (in four replicates of five) were subjected to nominal loading rates of 1, 10, 100 and 1000 mg/L for a period of 48 hours. The solutions remained unchanged for the duration of the test. Immobilization at each loading rate was recorded at 0, 24 and 48 hours. Chemical analysis was undertaken to measure the concentration of the test item, based on the peroxide, in limit test solution (loading rate of 1000 mg/L) throughout the test. In the limit test, immobilizations were 0 % in the control and the limit test solution (1000 mg/L nominal) after 48 hours.

In the range-finding test, no immobilization was observed at 1, 10,100 and 1000 mg/L nominal throughout the test. As the test item was not found to be toxic at the nominal loading rate of 1000 mg/L (limit test solution), chemical analysis was undertaken to measure the concentration of cyclohexylidenebis[tert-butyl] peroxide in this solution. The initial concentration of the test item measured in the limit test solution was 0.598 mg/L. The test item was not stable under the experimental conditions since its concentration fell below 80 % of the initial value during the test. The measured concentration was 0.0415 mg/L after 24 hours, corresponding to 7% of the initial concentration, and < 0.0394 mg/L (limit of quantification) after 48 hours. The measured concentration of the test item in the limit test solution at the beginning of the test (0.598 mg/L) was retained for data interpretation since a geometric mean of measured concentrations throughout the test could not be determined.

Hence, the highest concentration resulting in no immobilization at 48 hours was >= 1000 mg/L expressed as initial loading rate, corresponding to 0.598 mg/L expressed as actual concentration. The 48-hour EC50 of cyclohexylidenebis[tert-butyl] peroxide in a static test system is > 1000 mg/L expressed as initial loading rate (EL50), corresponding to 0.598 mg/L expressed as actual concentration (measured concentration at the beginning of the test in the saturated solution obtained from this loading rate of 1000 mg/L) for Daphnia magna.