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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
Study period:
2003-05-19 to 2003-12-18
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)
Qualifier:
according to guideline
Guideline:
EU Method C.2 (Acute Toxicity for Daphnia)
Qualifier:
according to guideline
Guideline:
ISO 6341 (Water quality - Determination of the Inhibition of the Mobility of Daphnia magna Straus (Cladocera, Crustacea))
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
- Concentrations:1.0, 2.2, 4.6, 46 mg/L and blank control
- Sampling method:
Fresh: 0 and 24 h
Old: 24 and 48 h
10 mL from approximate centre of vessels
- Sample storage conditions before analysis: Not applicable, samples analysed on day of sampling.
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: Test solutions with a concentration of 1.0. 10 and 100 mg/L were prepared seperately. After a 10 minutes treatment with ultrasonic waves to accelerate the disolving of the test substance in the test medium, the test solutions were clear and colourless but the 10 and 100 mg/L concentrations contained a layer of foam. After the fam had disappeared from the highest test concentrations a ten-fold dilution was prepared from the 1.0 mg/L concentration. The final test solutions were clear and colourless
Final: Test concentrations prepared daily from 46 mg/L stock solution. 10-20 minutes magnetic stirring used to accelerate disolving of the test substance in the test media. Layer of foam dissolved in test medium by use of air pressure.
- Controls: Blank
- Evidence of undissolved material (e.g. precipitate, surface film, etc): Thin foam on two highest test concentrations in final test.
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Daphnia magna
- Strain: not specified
- Source: In-house laboratory culture with known history
- Age at study initiation (mean and range, SD): < 24 h (2nd to 5th brood)
- Method of breeding: acyclical parthenogenesis
- Feeding during test: No

ACCLIMATION
- Acclimation period: Not applicable
- Acclimation conditions (same as test or not): No
- Type and amount of food: suspension of freshwater algae
- Feeding frequency: daily
- Health during acclimation (any mortality observed): not applicable, breeding continuous
Test type:
semi-static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Post exposure observation period:
None
Hardness:
250 mg CaCO3/L
Test temperature:
20.2 - 20.8°C
pH:
7.8 - 7.9
Dissolved oxygen:
8.8 -9.3 mg/L
Salinity:
Not applicable
Nominal and measured concentrations:
Final:
nominal: 1.0, 2.2, 4.6, 10, 22 and 46 mg/L (see attached document: 03-006GB Exposure concentrations)
Details on test conditions:
TEST SYSTEM
- Test vessel: 100 mL glass
- Material, size, headspace, fill volume: 80 mL medium
- Aeration: No
- Type of flow-through (e.g. peristaltic or proportional diluter): Not specified
- Renewal rate of test solution (frequency/flow rate): every 24 h
- 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: tap water purified by reverse osmosis
- Culture medium different from test medium: No

OTHER TEST CONDITIONS
- Adjustment of pH: No
- Photoperiod: 16 h light
- Light intensity: Not specified

TEST CONCENTRATIONS
- Spacing factor for test concentrations: =< 2.2
- Range finding study: yes (static)
- Test concentrations: 0.1 - 100 mg/L increasing by a factor of 10
- Results used to determine the conditions for the definitive study: Yes
Reference substance (positive control):
yes
Remarks:
potassium dichromate - periodical check on sensitivity of test system
Duration:
48 h
Dose descriptor:
LC50
Effect conc.:
7.9 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
mobility
Remarks on result:
other: 95% CL = 7.2 - 9.3 mg/L
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
4.6 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
mobility
Results with reference substance (positive control):
- Results with reference substance valid? Yes
- Mortality: LC100 = 0.56 mg/L
- LC50: 0.75 mg/L (48h)

Table 1: Acute immobilisation data (final test)

Nominal conc (mg/L)

Vessel number

Number Daphnia exposed

Response at 24 h

Response at 48 h

Number

Total %

Number

Total %

Blank control

A

5

0

0

0

0

B

5

0

0

C

5

0

0

D

5

0

0

1.0

A

5

0

0

0

0

B

5

0

0

C

5

0

0

D

5

0

0

2.2

A

5

0

0

0

0

B

5

0

0

C

5

0

0

D

5

0

0

4.6

A

5

0

0

0

0

B

5

0

0

C

5

0

0

D

5

0

0

10

A

5

3

40

4

80

B

5

2

4

C

5

2

4

D

5

1

4

22

A

5

4

85

5

100

B

5

5

5

C

5

4

5

D

5

4

5

46

A

5

5

100

5

100

B

5

5

5

C

5

5

5

D

5

5

5

Validity criteria fulfilled:
yes
Conclusions:
Under the conditions of the study, the test material did not induce acute immobilisation at a nominal concentration of 4.6 mg/L (NOEC) after 48 h.
The 48 h EC50 was 7.9 mg/L based on nominal concentrations (95% confidence limits of 7.2 - 9.3 mg/L).
Executive summary:

In a semi-static 48-hour acute immobilisation study in Daphnia performed in accordance with ISO 6341, OECD No 202 and EU Method C2 the test material was dosed at nominal concentrations of 1.0, 2.2, 4.6, 10. 22 and 46 mg/L to 20 Daphnia/group. The dose concentrations were chosen using a range finding study. A blank control was run in conjunction with the final test. Results of a positive control study on potassium dichromate were appended to the study to confirm sensitivity of the test system.

Analysis of samples taken at the start and 24 hours of exposure of the freshly prepared test solutions showed that measured concentrations were in agreement with nominal. Therefore EC50 and NOEC values were based on nominal concentrations.

The study met the acceptability criteria and was considered valid.

Under the conditions of the study, the test material did not induce acute immobilisation at a nominal concentration of 4.6 mg/L (NOEC) after 48 h. The 48 h EC50 was 7.9 mg/L based on nominal concentrations (95% confidence limits of 7.2 - 9.3 mg/L).

Description of key information

The EC50 (48-h) for Daphnia magna is 7.9 mg/L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates
Effect concentration:
7.9 mg/L

Additional information

One reliable study is available. In this study performed under GLP according to OECD TG 202 Daphnia magna (5/replicate, 4 replicates/concentration) were exposed to the substance under semi-static conditions for 48 hours at nominal concentrations of 0, 1.0, 2.2, 4.6, 10, 22 or 46 mg/L [Bouwman LM (2003a)]. The 48-h EC50 was 7.9 mg/L based on nominal test concentrations.