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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:
04 January 2010-06 January 2010
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: This study has been performes according to OECD and/or EC guidelines and according to GLP principles.
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
Qualifier:
according to
Guideline:
ISO 6341 (Water quality - Determination of the Inhibition of the Mobility of Daphnia magna Straus (Cladocera, Crustacea))
Deviations:
no
Qualifier:
according to
Guideline:
other: Guidance document on aquatic toxicity testing of difficult substances and mixtures, OECD series on testing and assessment number 23, December 14, 2000.
GLP compliance:
yes (incl. certificate)
Analytical monitoring:
yes
Details on sampling:
- Concentrations: all test concentrations and the control. Inaddition, the filter used for preparation of the test solutions was retained for possible analysis of the undissolved residue
- Sampling method:
Frequency at t=0 h and t=48 h
Volume 4.8 ml from the approximate centre of the test vessels
Storage Samples were stored in a freezer until analysis.
At the end of the exposure period, the replicates were pooled at each concentration before sampling
Vehicle:
no
Details on test solutions:
Preparation started with a loading rate of 100 mg/l applying one day of magnetic stirring to reach maximum solubility of the test substance in the test medium. The obtained aqueous mixture was filtered through a 0.45 µm membrane filter (Whatman, rc 55) and the clear and colourless filtrate was used as the highest test concentration. The lower test concentrations were prepared by subsequent dilutions of the filtrate in test medium.
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Daphnia magna (Crustacea, Cladocera) (Straus, 1820)
- Source: In-house laboratory culture with a known history.
- Age at study initiation: < 24 hours
- Method of breeding: With newborn daphnids, i.e. less than 3 days old, by placing about 250 of them into 5 litres of medium in an all-glass culture vessel.
- Feeding during test: No

Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
48 h
Hardness:
180 mg/l expressed as CaCO3
Test temperature:
between 20.6 and 21.7°C
pH:
Between 7.4 and 7.5
Dissolved oxygen:
Between 8.6 and 9.3 mg/l
Salinity:
not applicable
Nominal and measured concentrations:
The measured concentration of Barium in the samples taken from the undiluted filtrate at the start of the test was 0.57 mg/l. This concentration remained stable throughout the test period (99% of initial at the end of the test). The concentration of Lead was below the linear range of the calibration curve and therefore reported as lower than 0.01 µg/l. The analysis of the filter used for the preparation of the highest test concentration showed a relatively high content of lead.
Details on test conditions:
- Type (delete if not applicable): open
- Material, size, headspace, fill volume: glass, 100 ml, normal headspace
- Aeration: no
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4 for the highest concentration, 2 for the lower test concentrations
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Adjusted ISO medium: the following chemicals (analytical grade) are dissolved in tap water purified by Reverse Osmosis (RO-water, GEON Waterbehandeling, Berkel-Enschot, The Netherlands):
Macro salts: CaCl2.2H2O : 211.5 mg/l
MgSO4.7H2O: 88.8 mg/l
NaHCO3 : 46.7 mg/l
KCl : 4.2 mg/l
The hardness: 180 mg/l expressed as CaCO3 and the pH: 7.7 ± 0.3.

- Culture medium different from test medium: yes, for culturing M7 medium is used


OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 16 hours photoperiod daily

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : EC50 t=24 and t=48 h

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 10
- Test concentrations:0, 0.1, 1.0, 10 and 100% of a 0.45 µm filtered solution prepared at a loading rate of 100 mg/l

Reference substance (positive control):
yes
Remarks:
potassium dichromate (K2Cr2O7)
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
100 other: mg/l (loading rate)
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: 100% of the 0.45 µm filtered solution prepared at a loading rate of 100 mg/l
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
> 100 other: mg/l (loading rate)
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: 100% of the 0.45 µm filtered solution prepared at a loading rate of 100 mg/l
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
0.57 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
element
Remarks:
dissolved barium in fitrate
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
> 0.57 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
element
Remarks:
dissolved barium in fitrate
Basis for effect:
mobility
Details on results:
Behavioural abnormalities: no
- Mortality of control: no
- Other adverse effects control: no
No acute immobilisation was observed at any concentration tested.
Results with reference substance (positive control):
- Results with reference substance valid? yes
- EC50/LC50:
The 24h-EC50 was 0.53 mg/l with a 95% confidence interval between 0.46 and 0.64 mg/l.
The 48h-EC50 was 0.38 mg/l with a 95% confidence interval between 0.31 and 0.46 mg/l.
Validity criteria fulfilled:
yes
Conclusions:
Under the conditions of the present study Silicic acid(H2Si2O5), barium salt(1:1), lead-doped did not induce acute immobilisation of Daphnia magna exposed to a filtered solution prepared at a loading rate of 100 mg/l. The actual concentration of dissolved Barium in this filtrate was 0.57 mg/l.

The 48h-EC50 was beyond the range tested and therefore exceeded the solubility limit of Silicic acid(H2Si2O5), barium salt(1:1), lead-doped in test medium.

Description of key information

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
0.57 mg/L

Additional information