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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:
From 21 November 2017 to 22 December 2017
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Analytical monitoring:
no
Remarks:
All effect concentrations have been calculated from nominal concentrations.
Vehicle:
no
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Daphnia magna
- Strain/clone: originally sourced from a clone of genotype 5
- Source: From cultures maintained at Chemex Environmental International Ltd since July 2014
- Feeding during test: During the test the Daphnia magna were not fed.
- Food type: A suspension of Chlorella vulgaris.
- Frequency: Pre-test: Each working day.


Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Test temperature:
20.1 – 21.5 °C
pH:
6.66 - 7.94 pH
Dissolved oxygen:
-Initial Dissolved Oxygen at 0 Hours: 6.21mg/L
- Dissolved oxygen range in control and test concentrations throughout test: 6.21 – 7.15mg/L
Nominal and measured concentrations:
Nominal concentrations: 0 (control), 9.4, 17, 30, 55, and 100 mg/L.
Details on test conditions:
TEST SYSTEM
- Test vessel: glass dishes.
- Type: closed - the vessels were covered with a perspex sheet
- Material, size, headspace, fill volume: 40 mL, glass.
- Aeration: Limited aeration due to Perspex sheet clover
- Type of flow-through (e.g. peristaltic or proportional diluter): None
- Renewal rate of test solution (frequency/flow rate): None, static
- 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): No vehicle control
- Biomass loading rate: For homogenised test substances at weights 0.0047, 0.0085, 0.0150, 0.0275 and 0.0500 g the respective loading rates were 9.4, 17, 30, 55 and 100 mg/L ((+-)5% tolerance by weight)

WATER PARAMETERS
- Source/preparation of dilution water: Deionised water
- Total organic carbon: None
- Particulate matter: None
- Metals: None
- Pesticides: None
- Chlorine: None
- Alkalinity: Deionised water
- Ca/mg ratio: None
- Conductivity: None
- Salinity: None
- Culture medium different from test medium: None
- Intervals of water quality measurement: Measurements taken at 0 hours on remaining test solution, and at 48-hour endpoint on pooled replicates for each test and control solution.

OTHER TEST CONDITIONS
- Adjustment of pH: Not specified
- Photoperiod: 16 hours light and 8 hours dark
- Light intensity: Not specified

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Immobilisation

RANGE-FINDING STUDY
- Test concentrations: 0.1, 1, 10 and 100 mg/L expressed as loading rates
- Results used to determine the conditions for the definitive study: 0.1 mg/L test concentration was by dilution (addition of 2.5ml of the 10 mg/L preparation to 250 mL of dilution water) and for the 1mg/l test concentration, addition of 25 mL of the 10mg/L preparation to 250mL of dilution water
Reference substance (positive control):
yes
Remarks:
Potassium dichromate
Duration:
24 h
Dose descriptor:
EC50
Effect conc.:
>= 100 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat. (dissolved fraction)
Basis for effect:
mobility
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
75.338 mg/L
Nominal / measured:
estimated
Conc. based on:
test mat. (total fraction)
Basis for effect:
mobility
Remarks on result:
other: determined by Trimmed Spearman-Karber
Details on results:
- Behavioural abnormalities: No abnormal behaviour observed in the control animals
- Observations on body length and weight: None specified
- Other biological observations: None
- Mortality of control: No mortality observed in the control animals
- Other adverse effects control: None specified
- Abnormal responses: no signs of abnormality in the control, 9.4, 17, 30 and 55 mg/L 17 individuals displaying slower movement in 100mg/L at 24 hours. Slower movement was observed in one individual in 55 and 100 mg/L test concentrations at 48 hours.
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: Dissolved concentrations of the test substance were likely to be lower than stated as Decyltrimethoxysilane was not soluble in water.
- Effect concentrations exceeding solubility of substance in test medium: No test concentrations immobilised all twenty Daphnia after 48-hours
Results with reference substance (positive control):
- Results with reference substance valid? Yes.
- Relevant effect levels: 24 h EC50 of 1.4 mg/L of potassium dichromate
- Limit test: Not specified
- Dose-response test: Not specified
- ECx: 24 hour EC50 of 1.4 mg/L of potassium dichromate
Validity criteria fulfilled:
yes
Conclusions:
The 24-hour EC50 of Decyltrimethoxysilane to Daphnia magna were >100 mg/L (determined by direct observation)
The 48-hour EC50 of Decyltrimethoxysilane to Daphnia magna were 75.338 mg/L (determined by Trimmed Spearman-Karber)
Executive summary:

The short-term toxicity of Decyltrimethoxysilane to aquatic invertebrates was determined during a GLP-compliant study performed according to the OECD Testing Guideline 202. The species was Daphnia magna.

A range-finding test was performed to determine the concentrations to be used during the definitive test. As a result of this range-finding test, concentrations of 9.4, 17, 30, 55 and 100 mg/L were used during the definitive test.

The 24-hour EC50 was >100 mg/L (determined by direct observation) and the 48-hour EC50 was 75.338 mg/L (determined by Trimmed Spearman-Karber) under the conditions of the test.

 

Description of key information

The short-term toxicity of Decyltrimethoxysilane to aquatic invertebrates was determined during a GLP-compliant study performed according to the OECD Testing Guideline 202. The species was Daphnia magna.

A range-finding test was performed to determine the concentrations to be used during the definitive test. As a result of this range-finding test, concentrations of 9.4, 17, 30, 55 and 100 mg/L were used during the definitive test.

The 24-hour EC50 was >100 mg/L (determined by direct observation) and the 48-hour EC50 was 75.338 mg/L (determined by Trimmed Spearman-Karber) under the conditions of the test.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates
Effect concentration:
75.338 mg/L

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