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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:
July 27, 1994 - July 29, 1994
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
EU Method C.2 (Acute Toxicity for Daphnia)
Deviations:
no
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
- Concentrations: 100 mg/l (0 h), 100 mg/l (48 h), 50 mg/l (48 h)
- Sampling method: Samples were removed from the vessel of the lowest and highest treatment level for analysis of test substance; at 0 and 48 hours from the higher level (100 mg/l) and at 48 h from the lowest level (50 mg/l). The samples were analysed for Fosfomycin PEA salt by Istituto G. Donegani.
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: 10 mg/l of test material were made up to 100 ml with reconstituted water in glass beakers in order to obtain the concentration of 100 mg/l from which the remaining concentrations were prepared by dilution.
- Differential loading: at least 1 animal/2 ml
- Controls: yes, reconstituted water ( 0 mg/l of test substance)

Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Age at study initiation (mean and range, SD): <24 h
- Method of breeding: Laboratory breeding
- Feeding during test: No

BEFORE TEST:
- Feeding before test: Yes.
- Food type: green algae (Selenastrum capricornutum)
- Frequency: Three times a week.
- Light: 16/8 hours of light/dark daily
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Hardness:
251 mg/l CaCO3
Test temperature:
20 ºC
pH:
6.97 - 7.68
Dissolved oxygen:
7.9 - 8.0 mg/l
Nominal and measured concentrations:
Nominal concentrations (mg/l): 50, 59, 71, 84 and 100 mg/l.
Measured concentrations (mg/l): 82.40 (0 h - nominal concentration 100 mg/l), 83.50 (48 h - nominal concentration 100 mg/l), 48.07 (48 h - nominal concentration 50 mg/l)
Details on test conditions:
TEST SYSTEM
- Test vessel: Vials.
- Material, size, headspace, fill volume: Glass
- 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:
- Source/preparation of dilution water: According to ISO 6341-1982
- Sum of the calcium and magnesium ions: 2.5 mmol/l
- Ca/mg ratio: 4.1
- Na/k ratio: 10:1
- Culture medium different from test medium: Similar, to avoid necessity of adaptation prior to test.
- Parameter checking: At 0 and 48 hours of treatment the following parameters were checked in the treatment solutions: dissolved oxygen, pH and temperature.

OTHER TEST CONDITIONS
- Adjustment of pH: No.
- Photoperiod: During the test the animals were kept in the dark.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Observation of immobilization at 24 and 48 hours. Daphnia were considered immobile if not able to swim within 15 seconds of gentle agitation of the test container.

TEST CONCENTRATIONS
- Test concentrations: Nominal concentrations (mg/l): 50, 59, 71, 84 and 100 mg/l.
- Results used to determine the conditions for the definitive study: preliminary results
Reference substance (positive control):
no
Duration:
24 h
Dose descriptor:
EC50
Effect conc.:
91.8 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: 86.2-97.6 (95% CL)
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
86 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: 81.3-91.0 (95% CL)
Reported statistics and error estimates:
The EC50 at 24 and 48 h were calculated by the method of the Probit (Bliss-Finney).

Table 1. Acute immobilization study in Daphnia magna. Details of mobility and conditions of the test animals.

Concentration mg/l

Treated animals

Immobilized animals

24 h

Tot %

0

20

0

0

50

20

0

0

59

20

0

0

71

20

1

5

84

20

6

30

100

20

14

70

Table 2. Acute immobilization study in Daphnia magna. Details of mobility and conditions of the test animals.

Concentration mg/l

Treated animals

Immobilized animals

24 h

48 h

Tot %

0

20

0

0

0

50

20

0

0

0

59

20

0

0

0

71

20

1

2

10

84

20

6

10

50

100

20

14

16

80

 

Table 3. Values of EC50 at 24 and 48h.

Observation time (h)

EC50 (mg/L)

95% CL

24

91.8

86.2 – 97.6

48

86.0

81.3 – 91.0

 

Validity criteria fulfilled:
yes
Remarks:
No immobilization was observed in the controls and the dissolved oxygen concentrations at the end of the test were ≥ 3 mg/l in control and test vessels.
Conclusions:
EC50 value of test material in Daphnia magna at 24 h exposure period was 91.8 mg/l water.
EC50 value of test material in Daphnia magna at 48 h exposure period was 86.0 mg/l water.
Executive summary:

The study was performed to assess the acute immobilisation of Daphnia magna to determine the EC50 at 24 and 48 hours followed de EU Method C.2. 20 animals for each concentration subdivided into batches of 5 animals were exposed to the test material Fosfomycin PEA salt at nominal concentrations of 0 (control), 50, 59, 71, 84 and 100 mg/l water and observed for 48 hours. A static toxicity test procedure was followed. No animals were immobilized in the control group. The EC50 (based on mobility) at 24 and 48 hours was 91.8 and 86.0 mg/l respectively.

Description of key information

Key study. Test method according to EU Method C.2. GLP study.

The EC50 (based on mobility) in Daphnia magna at 48 h exposure period was 86.0 mg/l.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates
Effect concentration:
86 mg/L

Additional information

Key study: Test method according to EU Method C.2. GLP study. The EC50 (based on mobility) in Daphnia magna at 48 h exposure period was 86.0 mg/l.