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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:
18-06-2013 to 26-07-2013
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: study according to the guideline under GLP
Qualifier:
according to
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Qualifier:
according to
Guideline:
EU Method C.2 (Acute Toxicity for Daphnia)
GLP compliance:
yes (incl. certificate)
Analytical monitoring:
yes
Details on sampling:
- Concentrations: duplicate samples at all concentrations at 0 and 48 h. Samples were pooled. Only samples at 56 and 100 mg/L (as loading rate) were analysed (NOEC and LOEC)
- Sample storage conditions before analysis: frozen (-20 °C)
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: stirring for 23 hours, standing 1 hour and transfer via tube with Nescofilm seal by mid depth syphoning using a glass wool plug (WAF)
- Stirring period: recovery as TOC at 100 mg/L after 24 h stirring 2.67 mg/L; 96 h stirring 2.87 mg/L
- Differential loading: 10, 18, 32, 56 and 100 mg/L (all WAFs were prepared individually)
- Controls: untreated
- Evidence of undissolved material: microscopic evaluation of the WAFs did not show any undissolved material

Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: daphnia
- Source: in-house culture
- Age at study initiation : < 24 hours
- Method of breeding: reproduction by parthenogenesis
- Feeding during test: none

STOCK CULTURE
- Vessel: 150 mL beaker with Elendt 7 medium
- Type of food: algae suspension and Tetramin food flake suspension
- Feeding frequency: daily
- Environmental conditions: 16 h light, temperature 21 °C
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Hardness:
250 mg/L as CaCO3
Test temperature:
22-24 °C
pH:
8.0-8.2
Dissolved oxygen:
8.4-8.7 mg O2/L (97-101% of saturation)
Nominal and measured concentrations:
nominal 0, 10, 18, 32, 56 and 100 mg/L
measured (56 and 100 mg/L) : 2.50 and 1.78 mg/L at 0 and 48 h, 14.4 and 13.7 mg/L at 0 and 48 h

TWA at NOEC (56 mg/L) 2.1 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: 250 mL glass jars with ca 200 mL test preparation (covered)
- Aeration: none
- 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: reconstituted water (according to guidance)
- Alkalinity: pH 7.8 ± 0.2
- Ca/mg ratio: 4/1
- Conductivity: 5 uS
- Culture medium different from test medium: Elendt M7
- Intervals of water quality measurement:

OTHER TEST CONDITIONS
- Adjustment of pH: none
- Photoperiod: 16/8
- Light intensity: 568-597 Lux

EFFECT PARAMETERS MEASURED : immobilization

TEST CONCENTRATIONS
- Range finding study: 0, 1.0, 10, 100 mg/L as loading rate
- Test concentrations: 0, 10, 18, 32, 56 and 100 mg/L as loading rate
Reference substance (positive control):
yes
Remarks:
potassium dichromate
Duration:
48 h
Dose descriptor:
EL50
Effect conc.:
ca. 75 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: geometric mean between NOEC and LOEC
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
>= 2.1 mg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
dissolved
Basis for effect:
mobility
Details on results:
Range finding:
Immobility at 24 and 48 h: 0, 0, 0, 0,and 100% at 0, 1.0, 10 and 100 mg/L respectively

Definite test
Immobility at 24 and 48 h: 0, 0, 0, 0, 0 and 100% at 0, 10, 18, 32, 56 and 100 mg/L respectively

Results with reference substance (positive control):
EC50 potassium dichromate 0.71 mg/L
Reported statistics and error estimates:
NA
Validity criteria fulfilled:
yes
Conclusions:
The EL50 for daphnia is 75 mg/L. THe NOEC based on measured concentrations (TWA) is 2.1 mg/L.
Executive summary:

Daphnids were exposed to 0, 10, 18, 32, 56 and 100 mg/L test substance as loading rate during 48 hours. 100 % immobility was found at 100 mg/L, while no immobility was observed at any of the other loading rates. The analyses for accuracy of preparation at the maximum concentration attainable showed that the concentration at the NOEC was 2.1 mg/L (loading rate 56 mg/L). The EL50 is calculated as the geometric mean between NOEC and LOEC, i.e. 75 mg/L.

Description of key information

Daphnids were exposed to 0, 10, 18, 32, 56 and 100 mg/L test substance as loading rate during 48 hours. 100 % immobility was found at 100 mg/L, while no immobility was observed at any of the other loading rates. The analyses for accuracy of preparation at the maximum concentration attainable showed that the concentration at the NOEC was 2.1 mg/L (loading rate 56 mg/L). The EL50 is calculated as the geometric mean between NOEC and LOEC, i.e. 75 mg/L.

Key value for chemical safety assessment

Additional information

No EC50 based on measured concentrations was calculated. The NOEC as 48 -h TWA was 2.1 mg/L.