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Short-term toxicity to aquatic invertebrates

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short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2009-07-01 to 2010-06-11
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: OECD Guideline followed under GLP

Data source

Reference Type:
study report
Report Date:

Materials and methods

Test guideline
according to
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
GLP compliance:
yes (incl. certificate)

Test material

Details on test material:
- Name of test material (as cited in study report): Acetaldehyde
- Substance type: colourless liquid
- Physical state: liquid
- Storage condition of test material: cool in the dark

Sampling and analysis

Analytical monitoring:
Details on sampling:
Duplicate samples from the freshly prepared test media of all test concentrations and the control were taken at the start of the test.
For the determination of the stability of the test item under the test conditions and of the maintenance of the test item concentrations during the test period, two replicates from the actual test media of all test concentrations and the control were collected at the end of the test (after 48 hours).
The concentrations of the test item were analysed in the duplicate test media samples from both sampling times (0 and 48 hours). From the control samples only one of the duplicate samples was analysed from each of both sampling times.

Test solutions

Details on test solutions:
The test media of the nominal test item concentrations of 12.5, 25, 50 and 100 mg/L where prepared by adding the appropriate volume of test item directly in a glass flask. The lowest concentration was prepared by dilution of the test medium of nominal 12.5 mg test item/L. All mixing vessels were closed with a glass stopper to prevent evaporation of the test item.
The test media were prepared just before introduction of Daphnia (= start of the test).

Test organisms

Test organisms (species):
Daphnia magna
Details on test organisms:
Species: Daphnia magna (Straus), clone 5
Age at Test Start: Less than 24 hours old
Sex: Female
Origin: The Daphnia introduced in the test will be taken from our in-house laboratory culture.
Breeding Conditions: The Daphnia are bred in the laboratories of IBACON under similar temperature and light conditions as used in the test. The cultivation of the parental Daphnia is performed in reconstituted water of a similar quality with regards to pH, the constituent salts and total hardness as the test medium used in the test (see below). The test organisms will not be first brood progeny. The Daphnia in the stock culture are fed at least all working days with green algae (Desmodesmus subspicatus) freshly grown in the laboratories of IBACON.
Acclimatisation: Is not necessary since the breeding is performed in the same kind of test water (see 2.5).

Study design

Test type:
Water media type:
Limit test:
Total exposure duration:
48 h

Test conditions

2.5 mmol/L (= 250 mg/L) as CaCO3
Test temperature:
20 to 21 °C at test start; 20 °C at test end
7.8 to 8.0 at test start;
7.5 to 7.8 at test end; and thus the pH-value did not vary by more than 1.5 units
Dissolved oxygen:
8.6 to 8.7 mg/L at test start;
8.0 to 8.5 mg/L at test end
0.9 mmol/L
Nominal and measured concentrations:
100, 50, 25, 12.5 and 6.25 mg test item/L (nominal), corresponding to 104, 58.6, 30.3, 14.7 and 10.6 mg test item/L mean measured concentrations and a Control.
Details on test conditions:
- Light Regime: 16 h light : 8 h dark. The light intensity was 340 - 380 lux (measured once during the test).

- Test vessel: Glass beakers of at 110 mL volume filled completely (i.e. remaining head space reduced to a technical possible minimum of some mL) with test medium (about 110 mL of test medium) and kept close during the whole period of the study with a conical glass stopper.

- Test Environment: Controlled environment room

- Test Design: This study encompassed 6 treatment groups (5 dose rates of the test item, control) each containing 20 individuals. The immobility of the Daphnia was determined in a static 48-hour test by visual observation after 24 and 48 hours. The samples collected at start and after 48 hours were analysed via TOC-method.

- Endpoints: Number of immobile organisms after 24 and 48 hours.
Reference substance (positive control):
For the evaluation of the quality of the Daphnia clone used and the consistency of the experimental conditions, the reference item potassium dichromate p.a. is tested at least twice a year to demonstrate satisfactory test conditions.

Results and discussion

Effect concentrations
48 h
Dose descriptor:
Effect conc.:
57.4 mg/L
Nominal / measured:
Conc. based on:
test mat.
Basis for effect:
Details on results:
Biological results: After 48 hours of exposure no immobilisation of the test animals was observed in the control and up to and including the nominal test item concentration of 6.25 mg/L. At the nominal concentrations of 12.5 and 25 mg/L one animal was immobile. At the highest test item concentrations of nominal 50 and 100 mg/L, 3 and 20 daphnids were immobile, respectively.

Analytical results: At the start of the test 118 % of the nominal test concentration was found (average of test concentrations of nominal 100, 50 and 25 mg test item/L). After 48 hours test duration, 110 % of the nominal value was determined (average of test concentrations of nominal 100, 50 and 25 mg test item/L). During the test the Daphnia were exposed to a mean of 114 % of nominal. Therefore, all reported results refer to nominal concentrations. Measurement of Total Organic Carbon is a non-specific analytical method but attempts to establish a specific method for biological samples in the laboratories of IBACON failed. In order to investigate if the measured TOC values account for the concentration of Acetaldehyde in the test media stability experiments (non-GLP) under conditions similar to those of the biological experiment were performed at the sponsor. In these experiments stability of acetaldehyde in the test media was demonstrated.
Results with reference substance (positive control):
48h values
EC50 [mg/L]:0.742
Lower 95 % confidence values [mg/L]:0.632
Upper 95 % confidence values [mg/L]:0.871
NOEC [mg/L]:0.19
LOEC [mg/L]:0.31
Reported statistics and error estimates:
The 24-hour and 48-hour EC50 and the 95 % confidence limits were calculated by Probit analysis. For calculation 0 and 100 % values were replaced by 0.1 and 99.9 %.
The NOEC and LOEC after 24 and 48 hours were determined directly from the raw data.

Any other information on results incl. tables

Nominal Concentration

% of immobilizedDaphniaafter

[mg test item/L]

24 hours

48 hours



















Applicant's summary and conclusion

Validity criteria fulfilled:
The effect of the test item Acetaldehyde to Daphnia magna was assessed in a static dose-response test. The 48-hour EC50 value was calculated to be 57.4 mg test item/L.
Executive summary:

Acetaldehyde was investigated for acute toxicity to Daphnia magna according to OECD Guideline 202 in colsed vessel desing. The test fullfilled the validity criteria. The EC50 was 57.4 mg/L.