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Short-term toxicity to fish

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Reference
Endpoint:
short-term toxicity to fish
Type of information:
experimental study
Adequacy of study:
key study
Study period:
30 Oct - 03 Nov 2012
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Guideline study with acceptable restrictions
Qualifier:
according to
Guideline:
OECD Guideline 203 (Fish, Acute Toxicity Test)
Deviations:
yes
Remarks:
At 48 h one replicate had a dissolved oxygen concentration of 48% of saturation. At 0 h aeration was added in order to keep dissolved oxygen levels within the appropriate range. this deviation is not considered to have a negative impact on this study.
GLP compliance:
yes
Analytical monitoring:
yes
Vehicle:
yes
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Prior to exposure initiation, a 100 mg/L primary stock solution was prepared by weighing out 5.1339 g of (chloromethyl)triethoxysilane (4.9902 g as active ingredient) and bringing it to a total volume of 50 L with dilution water. Prior to the addition of the aliquot of test substance to the dilution water, 5.0 mL of tetrahydrofuran (THF) was applied directly to the test substance to facilitate solubility. The stock solution was mixed overnight with a Teflon®-coated stir bar and magnetic stir plate and then the water soluble fraction was siphoned from the mixing vessel. The resulting stock solution was observed to be clear and colorless with no visible undissolved test substance. This 100 mg/L primary stock solution was used as the exposure solution. The solvent control was prepared by adding 5.0 mL of THF to 50 L of dilution water. The control solution was prepared with dilution water only, (i.e., without the addition of test substance or solvent).
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): tetrahydrofuran (THF)
Test organisms (species):
Oncorhynchus mykiss (previous name: Salmo gairdneri)
Details on test organisms:
TEST ORGANISM
- Common name: Rainbow trout
- Strain: SMV Lot No. 12A130
- Source: Source: TroutLodge, Inc., Sumner, Washington, USA
- Length at study initiation (length definition, mean, range and SD): Mean total length = 47 mm (range 42 to 53 mm)
- Weight at study initiation (mean and range, SD): Mean wet weight = 1.3 g (range 0.77 to 1.8 g)
- Method of breeding: The fish were held in a 500 L fiberglass tank under a photoperiod of 16 hours light and 8 hours darkness. The temperature in the holding tank was 12 to 15 °C during the 14 days prior to exposure initiation and 13 ºC during the 48 hours prior to exposure. The fish were fed dry commercial fish food, Trout Chow, ad libitum, daily. Fish were not fed during the 24-hour period prior to exposure initiation or during the exposure period
- Feeding during test: none

ACCLIMATION
- Acclimation period: 2 weeks
- Acclimation conditions (same as test or not): yes
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
96 h
Hardness:
66 mg/L as CaCO3 (total hardness dilution water)
Test temperature:
13 - 15 °C
pH:
6.8 - 7.4
Dissolved oxygen:
7.1 - 9.9 mg O2/L (with exception of a single protool deviation of 5.0)
Nominal and measured concentrations:
control, 100 mg/L (nominal)
Details on test conditions:
TEST SYSTEM
- Test vessel:
- Material, size, headspace, fill volume: glass aquaria measured 39 × 20 × 25 centimeters (L × W × H)
- Aeration: yes
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 3
- No. of vessels per vehicle control (replicates): 3
- Biomass loading rate: mean of 0.83 g/L

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Laboratory well water
- Total organic carbon: mean of 0.39 mg/L
- Alkalinity: Total alkalinity as CaCO3: 22 mg/L
- Conductivity: 420 µS/cm

OTHER TEST CONDITIONS
- Photoperiod: photoperiod of 16 hours of light and 8 hours of darkness
- Light intensity: illumination range of 68 to 85 footcandles (730 to 910 lux)

EFFECT PARAMETERS MEASURED (with observation intervals if applicable): at 0, 24, 48, 72 and 96 hours mortalities were recorded and removed, biological observations, including adverse effects (e.g., darkened pigmentation), of the exposed rainbow trout and physical characteristics of the test solutions (e.g., presence of precipitate, film on the solution's surface) were made and recorded

TEST CONCENTRATIONS
- Range finding study: yes
- Results used to determine the conditions for the definitive study: Rainbow trout were exposed under static conditions to nominal concentrations of 0.10, 1.0, 10 and 100 mg/L. No mortality or adverse effects were observed.
Reference substance (positive control):
no
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
other: filtered test solution
Basis for effect:
mortality
Duration:
96 h
Dose descriptor:
NOEC
Effect conc.:
100 mg/L
Nominal / measured:
nominal
Conc. based on:
other: filtered test solution
Basis for effect:
mortality
Details on results:
Following 96 hours of exposure, no mortality or adverse effects were observed among fish exposed to the 100 mg/L treatment level, the control or the solvent control.

Description of key information

A 96-hour LC50of >100 mg/l and a NOEC of 100 mg/l, mortality, OECD 203, RL2

Key value for chemical safety assessment

Additional information

A 96-hour LC50value of > 100 mg/l and NOEC value of 100 mg/l have been determined for the effects of the test substance on mortality of Oncorhynchus mykiss based on nominal concentration of the substance. The study was conducted according to a standard guideline (OECD Method 203, Smithers Viscient, 2013a) and was selected as key study.

As the substance is subject to rapid hydrolysis, it is therefore likely that the test organisms were primarily exposed to the silanol hydrolysis product, retained in the test media.