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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:
10 December 2013 - 25 January 2015
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.2 (Acute Toxicity for Daphnia)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Analytical monitoring:
yes
Details on sampling:
- Concentrations: Nominal concentrations 0.0811, 0.178, 0.393, 0.864, and 1.90 mg/L.
- Sampling method: Samples were diluted with acetone prior to quantitation by gas chromatography with mass spectrometric detection (GC-MS).
- Sample storage conditions before analysis: Not applicable
Vehicle:
yes
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Controls: A solvent control containing 100µL/L THF in dilution water was prepared
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): Tetrahydrofuran
- Concentration of vehicle in test medium (stock solution and final test solution): 100µL/L (0.1 mL in 1000 mL)
- Evidence of undissolved material (e.g. precipitate, surface film, etc): None recorded

Note that test vessels were filled completely without any headspace, adn sealed using teflon lids and metal caps, due the issues caused by the volatility of the test substance.
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Strain: Straus
- Age at study initiation: Less than 24 hours old

ACCLIMATION (Culture conditions prior to test)
- Type and amount of food: Pseudokirchneriella subcapitata
- Feeding frequency: 0.1 to 0.2 mg carbon per daphnid per day
- Health during acclimation (any mortality observed): Not recorded.
Test type:
semi-static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Hardness:
254 mg/L (first batch) and 268 mg/L (second batch) as CaCO3.
Test temperature:
19.0 to 19.7°C
pH:
7.93 to 8.16
Dissolved oxygen:
9.01 to 9.57 mg/L
Nominal and measured concentrations:
Nominal: 0.0811, 0.178, 0.393, 0.864, and 1.90 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: Wheaton vials
- Type (delete if not applicable): closed
- Material, size, headspace, fill volume: Completely filled (c.a. 120 mL) allowing no headspace and sealed with teflon lids with metal caps
- Aeration: None
- Renewal rate of test solution (frequency/flow rate): Test medium was renewed every 24 hours
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4
- No. of vessels per vehicle control (replicates): 4
- Biomass loading rate: 24 mL medium per organism.

OTHER TEST CONDITIONS
- Photoperiod: 16 hours light: 8 hours dark

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Immobilisation, recorded at 24 and 48 hours from study initiation. Daphnia were considered to be immobile if they were unable to swim within approximately 15 seconds following gentle agitation of the test vessel.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2.2
- Range finding study
- Test concentrations: 0.019, 0.19, 1.90 mg/L. 100% immobilistation seen at 1.90 mg/L level, no immobilisation seen at other (0.019 and 0.19 mg/L) levels.
- Results used to determine the conditions for the definitive study: Yes
Reference substance (positive control):
no
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
0.158 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: 95% CL 0.129 - 0.170 mg/L
Key result
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
0.055 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Key result
Duration:
48 h
Dose descriptor:
LOEC
Effect conc.:
0.129 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Key result
Duration:
24 h
Dose descriptor:
EC50
Effect conc.:
0.201 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: 95% CL 0.186 - 0.245 mg/L
Duration:
24 h
Dose descriptor:
NOEC
Effect conc.:
0.129 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
24 h
Dose descriptor:
LOEC
Effect conc.:
0.245 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Details on results:
- Mortality of control: No Daphnia in the control or solvent control groups were immobile after 48 hours.
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: There was no evidence of undissolved material.
Validity criteria fulfilled:
yes
Conclusions:
The acute toxicity of TCD to Daphnia magna was assessed, in semi-static exposure conditions and in a sealed test system, over 48 hours, with renewal of media at 24 hours.
The 48-hour EC50 of TCD for the immobilisation of Daphnia magna was 0.158 mg/L (95% confidence limits of 0.129 and 0.17 mg/L) based on measured concentrations of TCD.
The 48 hour ‘no-observed effect concentration’ NOEC of TCD with Daphnia magna was 0.0553 mg/L (measured concentration) TCD.

Description of key information

48-Hour EC50 to Daphnia Magna = 0.158 mg/L.  NOEC = 0.0553 mg/L.

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
0.158 mg/L

Additional information