Dodecanoic acid, 2,2-dimethyl-3-oxopropyl ester

Short-term toxicity to aquatic invertebrates

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:

2004-08-18 to 2005-08-09

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:

adopted 2004

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Version / remarks:

adopted 1992

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Sampling preparation:
Aqueous samples (10.0 mL) were membrane filtrated (Nylon, 0.45 μm). The filtrate was acidified with 2M-HCl to pH 2 – 3. 10.0 mL of the filtrate were given on the top of a column with 5.0 g Extrelute. After 30 minutes, elution was slowly performed with ethyl acetate (50 mL, 30 minutes), the eluate was
rotated down to dryness and 500 μL ISTD-solution were added. At last, 400 μL of the solution were mixed with 50 resp. 100 μL SIL -Mix in vials, and silylation was performed at 80 °C for 60 minutes.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
1. Experiment:
- Method:
As solubility lies below 100 mg/L, the water-accommodated fraction was prepared for the test. This was done by weighing the nominal load of 100 mg/L, adding the corresponding amount of dilution water and shaking vigorously for 24 hours. The resulting solution was filtrated through 0.45 μm filters.
- Differential loading: 100 mg/L
- Controls: four vessels, each containing 20 mL dilution water and 5 daphnia
2. Experiment:
- Method:
The water-accommodated fraction was prepared for the test. This was done by weighing the nominal load of 100 mg/L, adding the corresponding amount of dilution water and stirring slowly for 24 hours. The solution was left to stand for half an hour. Then the lower phase was used for the test.
- Differential loading: 100 mg/L
- Controls: two vessels, each containing 20 mL dilution water and 5 daphnia
3. Experiment:
- Method:
A stock solution containing 1 g/L in acetone was prepared. This solution was used to prepare the treatment. 100 μL of the acetonic stock solution per litre were used.
- Differential loading: 0.1 mg/L
- Controls: two vessels, each containing 20 mL dilution water with 100 μL/L acetone and 5 daphnia
4. Experiment:
- Method:
A stock solution containing 10 g/L in acetone was prepared. This solution was used to prepare the treatment. 100 μL of the acetonic stock solution per litre were used.
- Differential loading: 1 mg/L
- Controls: two vessels, each containing 20 mL dilution water with 100 μL/L acetone and 5 daphnia
5. Experiment:
- Method:
A stock solution containing 10 g/L in acetone was prepared. This solution was used to prepare the treatment. 100 μL of the acetonic stock solution per litre were used.
- Differential loading: 1 mg/L
- Controls: four vessels, each containing 20 mL dilution water with 100 μL/L acetone and 5 daphnia
6. Experiment:
- Method:
A stock solution containing 10 g/L in acetone was prepared. This solution was used to prepare the treatment. 100 μL of the acetonic stock solution per litre were used at the most.
- Differential loading: 0.1 / 0.18 / 0.32 / 0.56 / 1 mg/L
- Controls: four vessels, each containing 20 mL dilution water with 100 μL/L acetone and 5 daphnia

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Daphnia magna
- Strain: Berlin
- Source: Umweltbundesamt Berlin
- Age at study initiation: between 0 and 24 hours
- Feeding during test: none

Test type:

other: 1 + 2 Experiment: static; 3-6 Experiment: semi-static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Test temperature:

1. 21.5 – 21.7 °C
2. 20.5 – 20.8 °C
3. 20.2 – 20.8 °C
4. 20.2 - 20.8 °C
5. 20.2 – 20.8 °C
6. 20.2 – 20.8 °C

pH:

1. 7.8 to 8.1
2. 7.8 to 8.0
3. 7.8 to 8.1
4. 7.8 to 8.0
5. 7.8 to 8.1
6. 7.8 to 8.1

Dissolved oxygen:

above 8 mg/L

Nominal and measured concentrations:

1. Experiment: 100 mg/L (nominal)
2. Experiment: 100 mg/L (nominal)
3. Experiment: 0.1 mg/L (nominal)
4. Experiment: 1 mg/L (nominal)
5. Experiment: 1 mg/L (nominal)
6. Experiment: 0.1, 0.18, 0.32, 0.56 and 1 mg/L (nominal)

Details on test conditions:

TEST SYSTEM
- Test vessel: glass beakers, nominal volume 50 L, tall shape
- No. of organisms per vessel: 5 daphnia
- No. of vessels per concentration (replicates): 2-4
- No. of vessels per control (replicates): 2-4

TEST MEDIUM / WATER PARAMETERS
in accordance to the guideline

OTHER TEST CONDITIONS
- Photoperiod: 16/8 hours, using neon tubes
- Light intensity: 20 ± 2 °C

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Duration:

24 h

Dose descriptor:

NOEC

Effect conc.:

0.32 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

0.18 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

1.4 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

ca. 1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: exact value after linear extrapolation: 1.02 mg/L

Details on results:

1 Experiment:
The daphnia were immobilized caused by an oily film on the surface. During the shaking period for the preparation of the WAF, an emulsion was produced. This emulsion couldn’t be separated by membrane filtration and during the test, the undissolved part of the test item rose to the surface. The effect on the daphnia can be stated as a physical effect. Therefore the experiment was repeated, but the test solution was prepared by stirring instead of shaking.
2 Experiment:
The daphnia were immobilized caused by an oily film on the surface. Obviously the undissolved parts of the test item couldn’t be separated by taking the lower phase. The effect on the daphnia can be stated as a physical effect. Therefore the experiment was repeated, but the test solution was prepared by spiking dilution water with a stock solution of the test item in acetone.
3. Experiment:
None of the daphnia were immobilized. As the solubility lies between 0.1 and 1 mg/L (due to the hydrolysis of the test item, no exact water solubility could be determined), it could not be confirmed that the limit of solubility was tested in this experiment. Therefore a further experiment with the treatment 1 mg/L was performed.
4. Experiment:
In the treatment after 24 hours, one daphnia was immobilized at the surface. Through the medium renewal, the daphnia was able to remobilize during the test. Based on these results, a further experiment with analytical determination was performed. In order to ensure testing at the maximal water solubility, the treatment 1 mg/L was chosen.
5. Experiment:
In the treatment 10 % of the daphnia were immobilized on the surface after 24 hours and 30 % after 48 hours. Therefore a further experiment with five concentrations was performed.
6. Experiment:
The immobility values changed in the same treatment between 24 and 48 hours. Caused by the medium renewal some of the daphnia were able to remobilize. In the concentrations 1.0 and 0.56 mg/L an thin oily film could be observed. This film has probably caused the immobilization. As a dose-response correlation is visible, this test was used to determine the results.

Results with reference substance (positive control):

- Results with reference substance valid? yes
- EC50: 1.9 mg/L

Reported statistics and error estimates:

The estimation of the EC50 of the test item was accomplished using the software OriginTM. The data were evaluated using linear fit on a probability-logarithmic scale.

In the fifth experiment at the beginning, after 4, 24 and 28 hours of the test, the content of the test item in each test solution was determined using GC. The measured concentration of each fresh test solution (medium renewal after 24 hours) was 45 and 54 % of the nominal concentration. This is caused by the hydrolysis of the test item which is faster than the average time needed for sample preparation. Four hours after the preparation of each new medium only 10 and 15 % of the nominal concentration were determined. The test item is not stable in water (as has been demonstrated in the respective study “water solubility determination”). Due to the fast degradation referring to determined values is not meaningful and only the nominal values were used for the determination of the biological results.

In the sixth experiment at the beginning, after 4, 24 and 28 hours of the test, the content of the test item in each test solution was determined using GC.

The measured concentrations of the fresh test solutions (at the start of the test and at the medium renewal after 24 hours) were between 21 and 66 % of the nominal concentrations. Sample preparation and clean-up requires about one hour. During this time, the test item undergoes already hydrolysis which probably caused these low recoveries. The measured concentrations 4 hours after preparing each new medium (4 and 28 hours after the start of the test) were between 8 and 35 % of the corresponding nominal concentration. The test item is not stable in water (as has been demonstrated in the respective study “water solubility determination”). Due to the fast degradation referring to determined values is not meaningful and only the nominal values were used for the determination of the biological results.

Validity criteria fulfilled:

yes

Conclusions:

The 48 h EC50 was determined about 1 mg/L (exact value after liner extrapolation: 1.02 mg/L) and the 48 h NOEC was 0.18 mg/L.

Executive summary:

The study was performed in order to evaluate the toxic potential of 2,2-Dimethyl-3-lauroyloxy-propanal towards freshwater shrimp, using the species Daphnia magna. Six experiments were performed. As the test item is poorly water soluble, the “water-accommodated fraction” was tested in the first experiment. This was done by weighing the nominal load 100 mg/L, adding the corresponding amount of dilution water and shaking vigorously for 24 hours. The resulting solution was filtrated through 0.45μm filters. The daphnia were immobilized on the surface already after 24 hours caused by an oily phase of the test item. The second experiment was performed likewise but with stirring instead of shaking. The resulting solution was left to stand for about 30 minutes. The lower phase was used for the test which was performed as a semi-static test. After 24 hours, the daphnia were immobilized on the surface. The oily film was visible again. All following experiments were performed under semi-static conditions with medium renewal after 24 hours. For the third and fourth experiment, a stock solution in acetone was prepared. The treatments 0.1 and 1 mg/L were prepared by spiking the corresponding amount of dilution water with this stock solution. The treatment 1 mg/L was used as lying well above maximal water solubilityof 0.227 mg/L. No daphnia were immobilized after 48 hours. In the control, the same concentration of acetone didn’t show any effect. Based on these experiments, the fifth experiment was performed as a limit-test using the treatment 1 mg/L with a acetone-spiked test solution. After 48 hours 30 % of the daphnia were immobilized on the surface. Therefore the last experiment was performed using five concentrations between 0.1 and 1 mg/L. Twenty daphnia were exposed to the test item for 48 hours in a semi-static test system. After 24 and 48 hours, the immobilized daphnia were counted. As no daphnia were dead after 24 hours, but immobilized on the surface, some of them were able to remobilize during the test. This was potentially due to the test item’s physicochemical properties causing film-formation at the top of the water phase (as noted at higher concentrations). None of the animals were immobilized in the control. The 48 h EC50 was determined about 1 mg/L (exact value after liner extrapolation: 1.02 mg/L) and the 48 h NOEC was 0.18 mg/L. These data were already submitted in a NONS dossier under Directive 92/32/EEC (notification number 05-04-1922-00 from 2005-10-25) and considered valid and uncritical from the German Competent Authority (BAUA).

Description of key information

Aldehyde L was assessed in a short-term toxicity to inverterbrates study according to EU-method C.2 and OECD guideline 202. Daphnia were exposed to static and semi-static conditions at different nominal concentration. The 48 h EC50 was determined about 1 mg/L (exact value after liner extrapolation: 1.02 mg/L) and the 48 h NOEC was 0.18 mg/L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Dose descriptor:

EC50

Effect concentration:

1.02 mg/L

Additional information

The study was performed in order to evaluate the toxic potential of 2,2-Dimethyl-3-lauroyloxy-propanal towards freshwater shrimp, using the species Daphnia magna. Six experiments were performed. As the test item is poorly water soluble, the “water-accommodated fraction” was tested in the first experiment. This was done by weighing the nominal load 100 mg/L, adding the corresponding amount of dilution water and shaking vigorously for 24 hours. The resulting solution was filtrated through 0.45μm filters. The daphnia were immobilized on the surface already after 24 hours caused by an oily phase of the test item. The second experiment was performed likewise but with stirring instead of shaking. The resulting solution was left to stand for about 30 minutes. The lower phase was used for the test which was performed as a semi-static test. After 24 hours, the daphnia were immobilized on the surface. The oily film was visible again. All following experiments were performed under semi-static conditions with medium renewal after 24 hours. For the third and fourth experiment, a stock solution in acetone was prepared. The treatments 0.1 and 1 mg/L were prepared by spiking the corresponding amount of dilution water with this stock solution. The treatment 1 mg/L was used as lying well above maximal water solubility of 0.227 mg/L. No daphnia were immobilized after 48 hours. In the control, the same concentration of acetone didn’t show any effect. Based on these experiments, the fifth experiment was performed as a limit-test using the treatment 1 mg/L with a acetone-spiked test solution. After 48 hours 30 % of the daphnia were immobilized on the surface. Therefore the last experiment was performed using five concentrations between 0.1 and 1 mg/L. Twenty daphnia were exposed to the test item for 48 hours in a semi-static test system. After 24 and 48 hours, the immobilized daphnia were counted. As no daphnia were dead after 24 hours, but immobilized on the surface, some of them were able to remobilize during the test. This was potentially due to the test item’s physicochemical properties causing film-formation at the top of the water phase (as noted at higher concentrations). None of the animals were immobilized in the control. The 48 h EC50 was determined about 1 mg/L (exact value after liner extrapolation: 1.02 mg/L) and the 48 h NOEC was 0.18 mg/L. These data were already submitted in a NONS dossier under Directive 92/32/EEC (notification number 05-04-1922-00 from 2005-10-25) and considered valid and uncritical from the German Competent Authority (BAUA).