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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:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
GLP study according to protocol. The CoA included in the report did not contain enough detail on composition; a statement of the composition is attached to the robust summary. No detailed description of the results of the chemical analyses and system stability.
Qualifier:
according to
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Deviations:
no
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
At the start of the test samples of about 15 mL were taken from the test vessels with the lowest (3.3 mg/L), the middle (10.7 mg/L) and the highest (34.6 mg/L) concentration and the control, just before the distribution of the test solutions over the four batches and adding the test animals. At the end of the test the solutions from the four batches were combined and mixed and about 15 mL samples from the above mentioned concentrations and the control were used for analysis. Samples were stored in a refrigerator until analyses.
Vehicle:
no
Details on test solutions:
The test substance was soluble in water. A stock solution containing approximately 1 g/L of 2,4-Pentanedione, peroxide in solvent was prepared as follows: to an accurately measured amount of approximately 1 g. of test substance approximately 800 ml of deionized water was added. The test substance dissolved well at room temperature under stirring. The pH of the stock solution was neutralized with a 1 M. sodium hydroxide solution. Thereafter, deionized water was added up to a final volume of 1000 mL. A homogeneous, clear stock solution was obtained which was stored in the refrigerator until further use.

The test solutions were prepared by addition of the required amounts of stock solution to the test medium to obtain the following concentrations of 2,4-Pentanedione, peroxide : 3.3, 5.9, 10.7, 19.3 and 34.6 mg/L. A control containing only test medium was included in the test.
Test organisms (species):
Daphnia magna
Details on test organisms:
The test was performed with Daphnia magna (water fleas), of which a continuous culture is maintained at Akzo Nobel Chemicals Research, Arnhem, Dept. CGS-ENV. The animals used in the test were less than 24 hours old at the beginning of the test and were obtained from parent animals having an age of 2-4 weeks.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Test temperature:
20.7-21.4 °C
pH:
7.7-8.2
Dissolved oxygen:
8.5-8.9 mg O2/L
Nominal and measured concentrations:
Nominal active ingredient: 3.3, 5.9, 10.7, 19.3 and 34.6 mg/L
Measured geometric mean active ingredient: 1.7, - , 7.6, -, 22.1 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: 400 mL glass beakers containing 250 mL of test solution
- Type (delete if not applicable): open, covered with glass plates
- Aeration: no
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Dilution water: Dutch Standard water was used, with a pH of approximately 8.2 and a hardness of approximately 12 °dH, containing per liter of deionized water: 100 mg of NaHCO3, 20 mg of KHCO3 200 mg of CaCl2*2H2O and 180 mg of MgSO4*7H2O. Aerated before use.
- Culture medium different from test medium: No data

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 16h
- Light intensity: ambient light provided by fluorescent tubes.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : immobility
Reference substance (positive control):
not specified
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
7.1 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
act. ingr.
Basis for effect:
mobility
Remarks on result:
other: Recalculated by the reviewer. EC50 reported as nominal active ingredient concentration.
Details on results:
Results as given in the report:
The EC50 - 48 h was calculated to be 10.91 mg/L with 95% confidence limits of 9.39 and 12.68 mg/L, the EC50 - 24h was 13.91 mg/L. The highest concentration causing no immobility (no observed effect concentration, NOEC) after 48 hours was not observed due to an effect at the lowest concentration tested. The EC100 was 19.3 mg/L, which was observed after 24 hours.
Sublethal effects, such as floating at the surface, were not observed in the test concentrations where no immobility was observed.

Remark from the reviewer:
These results were recalculated to geometric mean of the active ingredient concentration instead of nominal active ingredient concentrations as the test material was not stable during the test. The result mentioned in the section on Effect concentrations is the value converted to geometric mean of the active ingredient.

Analytical results:
The results show that the measured concentrations of the three samples from the beginning of the test are 9 to 12% lower than the nominal concentrations. No test substance was detected in the control samples. At the end of the test 2,4-Pentanedione, peroxide concentrations were measured which are 34 to 52% lower than the concentration at the beginning of the test. Quantification of the decrease of the lowest concentration tested during the test was not possible, due to a reduction of the concentration below the detection limit. These results show that the test substance is probably not stable under test conditions.
Reported statistics and error estimates:
The EC50 was calculated with the computer program TOXCALC TM version 5.0, using the trimmed Spearman-Karber method. The concentrations causing zero and 100% immobility were if possible, derived directly from the test observations.
Validity criteria fulfilled:
yes
Conclusions:
This study is reliable with the above mentioned restrictions. It is performed according to OECD guideline 202 under GLP and all validity criteria were fulfilled.
The test substance was not stable during the test and therefore measured geometric mean concentrations were used. The calculated endpoints are adequate for C&L and risk assessment purposes.
Executive summary:

The acute toxicity of Acetyl acetone peroxide in solvent to Daphnia magna (water flea) was tested under static conditions for 48 hours in accordance with OECD and EEC guidelines for testing of chemicals. The test was performed in compliance with Good Laboratory Practice (GLP).

The chemical analyses carried out showed that the concentration of the test compound during the test decreased below 80% of the concentration at the beginning of the test. The following acetyi acetone concentrations were tested: 3.3, 5.9, 10.7, 19.3 and 34.6 mg/L

The EC50 (48 h) was calculated to be 10.91 mg/L with 95% confidence limits of 9.39 and 12.68 mg/L, based on active ingredient.

The highest concentration causing no immobility (no observed effect concentration, NOEC) after 48 hours was not observed due to an effect at the lowest concentration tested. The EC50 was 19.3 mg/L, which was observed after 24 hours.

Sublethal effects, such as floating at the surface, were not observed in the test concentrations where no immobility was observed.

Remark from the reviewer: The results given in this summary are as given in the report, so have not been converted to measured geometric mean concentrations.

Description of key information

The48h-EC50 for aquatic invertebrates is 7.1 mg a.i./L (measured geometric mean).

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
7.1 mg/L

Additional information