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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:
2000-04-12 to 2000-05-04
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Qualifier:
according to
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Version / remarks:
194-04-04
Deviations:
no
GLP compliance:
no
Remarks:
The study described in this report was conducted in accordance with SN EN 45001.
Specific details on test material used for the study:
Batch 1210.9225
Analytical monitoring:
no
Remarks:
No chemical analyses of the test media were conducted. For the calculation of the effective concentrations, the nominal contents of the test solutions were use, assuming the test compound to be stable in water over 48 h.
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
Prior to the test, a batch of reconstituted water was aerated vigorously over a period of 2h. Final test concentrations were prepared with this aerated water by dilution of stock solutions of the test substance. 2 h before the test, vessels were filled with the formulated media to allow equilibration of pH, oxygen and temperature. Daphnia, which had been selected in size, were acclimatized to the reconstituted water for 4 hours before introduction into the test media. The pH was not adjusted before the test. Based on the results of a range finding test, nominal concentrations of the test substance forming a geometric series were added to the test media. A blank of test medium without test substance or other additives served as a control.

Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Daphnia magna
- Strain/clone: Daphnia magna (Straus, 1820)
- Source: no data
- Age of parental stock (mean and range, SD): no data
- Feeding during test: no data
- Food type: 15 g sera micropan homogenized in 1L deionized water
- Frequency: Once a day, except weekends.

ACCLIMATION
- Acclimation period: 4 h
- Acclimation conditions (same as test or not): same
- Type and amount of food: no data
- Feeding frequency: no data
- Health during acclimation (any mortality observed): no data

Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Test temperature:
20.0 (± 0.5) °C
pH:
7.9 - 8.0
Dissolved oxygen:
6.5 - 7.0 mg/l
Salinity:
no data
Conductivity:
no data
Nominal and measured concentrations:
Nominal concentrations:
0.25, 12.5, 25,.0, 50.0, 75.0, 100.0 mg/l
Details on test conditions:
TEST SYSTEM
- Test vessel: 100 ml flasks, all-glass, with 50 ml of test medium
- Aeration: not aerated
- No. of organisms per vessel: 20
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 2

TEST MEDIUM / WATER PARAMETERS
Continuously aerated reconstituted water (ISO 6341 (3)); prepared with distilled water (conductivity <1.5 I-lS/cm).
The final test medium contained 25 mill of each of the following 4 stock solutions:
CaCI2 x 2 H20, 11.76 g/l; MgS04 x 7 H2O, 4.93 g/l; NaHCOs, 2.59 g/l; KCI, 0.23 g/l.
The sum of the Ca and Mg ions in this solution is 2.5 mmol/l.
The ratio of Ca:Mg ions is 4:1 and of Na:K ions is 10:1.
The total alkalinity of this solution is 0.8 mmol/l

OTHER TEST CONDITIONS
- Adjustment of pH: The pH was not adjusted before the test.
- Photoperiod: 16 h photoperiod a day, supplied by overhead white fluorescent tubes
- Light intensity: no data

EFFECT PARAMETERS MEASURED: Observations of immobile Daphnia were made after 24 and 48 h of exposure.

VEHICLE CONTROL PERFORMED: no

RANGE-FINDING STUDY
- Test concentrations: 1,10 and 100 mg/I
- Results used to determine the conditions for the definitive study:
Based on the data of the range finding test nominal concentrations with a spacing factor of 2 of 6.25, 12.5, 25, 50 and 100 mg/I and additionally 75 mg/I
were chosen for the definitive test.
Reference substance (positive control):
no
Remarks:
Periodically conducted reference test with potassium dichromate.
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
42.4 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: 95 % confidence limits: 32.4-57.5 mg/I
Duration:
24 h
Dose descriptor:
EC50
Effect conc.:
77.2 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: 95 % confidence limits: 66.1-95.5 mg/I)
Details on results:
The experimentally determined no-effect concentration (NOEC, ECo) was 12.5 and 6.25 mg/I after an exposure of 24 and 48 h, respectively.
Reported statistics and error estimates:
The coefficients (r2) of the regression curves for the 24 and 48 h observations were 0.950 and 0.878, respectively.

Definitive test: Immobilization of Daphnia magna after 24 and 48 h of exposure to the test material:

 

Nominal

concentration (mg/I)

Code

Number of

individuals per test vessel

Immobile

Daphnia (No./vessel) 24 h

Immobile

Daphnia (No./vessel) 48 h

% immobile

Daphnia after 24 h of exposure

% immobile

Daphnia after 48 h of exposure

Control

A

20

0

0

0

0

0.0

B

20

0

0

0

0

 

C

20

0

1

0

5

6.25

A

20

0

0

0

0

 

B

20

0

0

0

0

12.5

A

20

0

1

0

5

 

B

20

1

4

5

20

25

A

20

4

6

20

30

 

B

20

4

5

20

25

50

A

20

6

8

30

40

 

B

20

7

7

35

35

75

A

20

9

13

45

65

 

B

20

11

15

55

75

100

A

20

11

19

55

95

 

B

20

12

17

60

85

Validity criteria fulfilled:
yes
Conclusions:
Based on the immobilization data the nominal median effect concentration (EC50) of Guanidine thiocyanate to Daphnia magna for 48 h was calculated to be 42.4 mg/I (95 % confidence limits: 32.4-57.5 mg/I).
Executive summary:

The 48h-acute toxicity of Guanidine thiocyanate to Daphnia magna was studied under static conditions.  Daphnids were exposed to control, and test chemical at (nominal) concentration of 0.25, 12.5, 25, 50.0, 75.0, 100.0 mg/l for 48 hr.  Immobilization effects were observed daily.  The 24 and 48 – hour EC50was 24 and 48 h was calculated to be 77.2 mg/l (95 % confidence limits: 66.1-95.5 mg/l) and 42.4 mg/l (95 % confidence limits: 32.4-57.5 mg/l), respectively.

The experimentally determined no-effect concentration (NOEC, EC0) based on immobilization was 12.5 and 6.25 mg/l after an exposure of 24 and 48 h, respectively.

This study is classified as acceptable and satisfies the guideline requirements for an acute toxicity study with freshwater invertebrates.

 

Results Synopsis

Test Organism: Daphnia magna < 2 mm

Test Type: Static

NOEL 48h: 6.25 mg/l (nominal)                  experimentally determined 

EC50 48h: 42.4 mg /l (nominal)                  95% C.I.: 32.4 - 57.5mg/I (nominal)

Endpoint(s) Effected:  mobility

 

Description of key information

The 48h-acute toxicity of Guanidine thiocyanate to aquatic invertebrates (Daphnids) was studied. The 48h-EC50 based on immobilization was found to be 42.4 mg/l (nominal, 100 % a.i.).

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
42.4 mg/L

Additional information

The 48h-acute toxicity of Guanidine thiocyanate to Daphnia magna was studied under static conditions.  Daphnids were exposed to control, and test chemical at (nominal) concentration of 0.25, 12.5, 25, 50.0, 75.0, 100.0 mg/l for 48 hr.  Immobilization effects were observed daily.  The 24 and 48 – hour EC50was 24 and 48 h was calculated to be 77.2 mg/l (95 % confidence limits: 66.1-95.5 mg/l) and 42.4 mg/l (95 % confidence limits: 32.4-57.5 mg/l), respectively.

The experimentally determined no-effect concentration (NOEC, EC0) based on immobilization was 12.5 and 6.25 mg/l after an exposure of 24 and 48 h, respectively.