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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:
12 -14 Sep 2000
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Qualifier:
according to
Guideline:
EU Method C.2 (Acute Toxicity for Daphnia)
Version / remarks:
1992
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
- Concentrations: All test concentrations were sampled after 0 and 48 h.
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: A stock solution was prepared to prepare the test solutions. 119.9 mg of the test substance were added to 1 L of dilution water and treated for 60 sec with an ultra-turrax and afterwards stirred 24 h an a magnetic stirrer.
- Eluate: no
- Differential loading: no
- Controls: yes, test medium control
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: water flea
- Feeding during test: None

ACCLIMATION
- Acclimation conditions: A population of parthenogenetic females is maintained in the test facility under constant temperature conditions (20 ± 1 °C) at a 16 : 8 h light-dark photoperiod (illumination: < 1000 lux). The culture water (M4 medium) is partly renewed once a week. Mortalities of parent Daphnia during the culture period are recorded daily in a semi-quantitative way. The neonates are separated from their parent Daphnia by filtration prior to the test.
- Type and amount of food: The Daphnia are exclusively fed with unicellular green algae (Scenedesmus subspicatus CHODAT) 'ad libitum'.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Hardness:
15.5 °dH (= 276.7 mg/L CaCO3)
Test temperature:
20.0 - 20.4 °C
pH:
7.6 - 7.9
Dissolved oxygen:
93.3 - 95.0% saturation
Nominal and measured concentrations:
Nominal: control, 24.6, 49.7, 98.9 mg/L
Measured (TOC after 0 h): < 2 mg/L, 23.4 mg/L, 46.8 mg/L, 93.6 mg/L
Measured (TOC after 48 h): < 2 mg/L, 22.1 mg/L, 41.6 mg/L, 88.4 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: 50 mL glass beakers (fill volume: 20 mL, headspace: 30 mL)
- Aeration: none
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 2

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: according to guideline (M4 medium)
- Culture medium different from test medium: same as test
- Intervals of water quality measurement: after 0 and 48 h

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 16 h light / 8 h darkness

EFFECT PARAMETERS MEASURED
- Mobility and behaviour was investigated after 24 and 48 h.
Reference substance (positive control):
not specified
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
45.5 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: Geometric mean of EC0/EC100
Duration:
48 h
Dose descriptor:
EC0
Effect conc.:
22.8 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
EC100
Effect conc.:
91 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Details on results:
- Immobilisation in control: 0%

Table 1: Immobilisation of D. magna during the study

Nominal concentration

% immobilisation

24 h

48 h

Control

0

0

24.6 mg/L

0

0

49.7 mg/L

0

65

98.9 mg/L

75

100

Table 2: TOC measurement: Nominal concentration 24.6 mg/L

Chemical analysis

0 h

48 h

TOC values [mg/L]

18

17

Equivalent to test substance [mg/L]

23.4

22.1

Table 3: TOC measurement: Nominal concentration 49.7 mg/L

Chemical analysis

0 h

48 h

TOC values [mg/L]

36

32

Equivalent to test substance [mg/L]

46.8

41.6

Table 4: TOC measurement: Nominal concentration 98.9 mg/L

Chemical analysis

0 h

48 h

TOC values [mg/L]

72

68

Equivalent to test substance [mg/L]

93.6

88.4

Validity criteria fulfilled:
yes
Conclusions:
The test substance caused immobilisation of Daphnia magna in a guideline study according to EU Method C.2 (GLP). An EC50 (48 h) of 45.5 mg/L was calculated as geometric mean of EC0 and EC100, based on arithmetic mean of measured concentrations.

Description of key information

EC50 (48 h): 45.5 mg/L (geometric mean of EC0/EC100)

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
45.5 mg/L

Additional information

One experimental study is available investigating the toxicity of the test item to aquatic invertebrates according to EU Method C.2 under GLP conditions (2000). Daphnia magna was exposed for 48 h to nominal concentrations of 24.6, 49.7 and 98.9 mg/L under static conditions. The actual test concentrations in the test medium were verified by analysis of the total organic carbon (TOC) content. TOC measurements resulted in concentrations of 23.4 mg/L, 46.8 mg/L, 93.6 mg/L at test start and 22.1 mg/L, 41.6 mg/L, 88.4 mg/L after 48 h.
100% immobilization was recorded at the highest concentration of 98.9 mg/L whereas 0% immobilization resulted at nominal 49.7 mg/L. Thus, the EC50 was calculated as geometric mean of EC0 and EC100 resulting in 45.5 mg/L based on arithmetic mean of measured concentrations.