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Short-term toxicity to fish

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Endpoint:
short-term toxicity to fish
Type of information:
experimental study
Adequacy of study:
key study
Study period:
29 Sep - 03 Oct 2009
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 203 (Fish, Acute Toxicity Test)
GLP compliance:
yes (incl. certificate)
Analytical monitoring:
no
Vehicle:
yes
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: A dosing stock solution was prepared by mixing 1.52 mL of trichloro(phenyl)silane (density 1.32 g/cm³) with 2.0 mL of tetrahydrofuran (THF) using Hamilton syringes. The 100 mg test item/L test solution was prepared prior to test initiation by adding 1.76 mL of the dosing stock solution to 10 L dilution water using a Hamilton syringe. Prior to addition of the dosing stock solution, the container containing the dilution water was placed on a magnetic stirrer. The spiked solution was stirred continuously over night. The pH of the solution was then adjusted to 7.0 with 1 N sodium hydroxide (NaOH).

A control vessel containing only dilution water and a solvent control vessel containing dilution water and 0.10 mL/L THF were established and maintained under the same conditions as the treatment solutions.
Test organisms (species):
Oncorhynchus mykiss (previous name: Salmo gairdneri)
Details on test organisms:
TEST ORGANISM
- Source: The trout were originally obtained from Forellenzucht P. Hohler-Gasser, a commercial supplier located in Zeiningen, Switzerland.
- Length at study initiation (length definition, mean, range and SD): mean total length of 34 mm (range 29 to 39 mm).
- Weight at study initiation (mean and range, SD): mean wet weight of 0.42 g (range 0.20 to 0.63 g)
- Feeding during test: none

ACCLIMATION
- Acclimation conditions (same as test or not): Prior to testing, the fish were maintained in a holding tank (under renewal conditions) under a photoperiod of 16 hours light and 8 hours darkness with a 30 min transition period.
- Culture water: The culture water was modified well water from the municipality of Horn, deionized with a Culligan Reverse Osmosis system. The deionized well water was reconstituted according to the formulation given in the Official Journal of the European Communities
- Type and amount of food: The fish were fed Hokovit 502, a dry, commercially available food, generally once daily. Fish were not fed during the 24-hour period prior to test initiation and during the exposure period.
- Health during acclimation (any mortality observed): No mortality was observed among the test fish population during the 12-day period prior to testing.
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
96 h
Hardness:
160 mg/L as CaCO3
Test temperature:
14.9 - 15.5 °C
pH:
7.2 - 7.5
Dissolved oxygen:
8.9 - 10.7 mg/L
Nominal and measured concentrations:
Nominal concentrations: Control, solvent control and 100 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: The test vessels were 12.5 L vessels constructed of stainless steel, each containing 10 L of test solution. The test vessels were loosely covered with a glass plate during the 96-hour exposure.
- Replication: One test vessel for the 100 mg test item/L treatment and for the controls was prepared.
- Number of test organisms per treatment: The test was initiated when seven trout were impartially selected and distributed to each test vessel.
- Biomass loading: The mean organism loading was 0.3 g of biomass per litre of test solution.
- Temperature: The test vessels were placed in a water bath in order to maintain exposure solution temperatures at 15 ± 2 °C.
- Aeration: Test solutions were gently aerated (with oil-free air) throughout the duration of the exposure period.
- Lighting: The test was illuminated to a light intensity of 200 to 500 lux using fluorescent bulbs. A 16-hour light, 8-hour dark photoperiod was maintained with an automatic timer.
- Observations: All test vessels were examined at 0, 24, 48, 72 and 96 hours of exposure for mortality. In addition observations of the physical characteristics of the test solutions (e.g., clear solution, precipitate, film on the surface of the test solution) were made and recorded at each 24-hour interval. Biological observations, including adverse effects on the exposed trout, were performed and recorded at each 24-hour interval. Effects for this study were based on mortality, defined as the lack of movement by the exposed organisms (i.e., absence of gill movement and reaction to gentle prodding).
- Water quality and lighting: The pH, dissolved oxygen (DO) concentration and temperature were measured at 0, 24, 48, 72 and 96 hours in each test solution. Continuous temperature monitoring was performed in the control solution throughout the exposure period. The pH was measured with a WTW 323 pH meter, dissolved oxygen and daily temperature were measured using a WTW Oxi 325 dissolved oxygen meter. Light intensity was measured with a Pancontrol LX 1308 lux meter.
Reference substance (positive control):
no
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality
Duration:
96 h
Dose descriptor:
NOEC
Effect conc.:
>= 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality
Details on results:
- Mortality of control: 0%
Reported statistics and error estimates:
Since no 50% mortality was observed during the 96 hours of exposure, no 24-, 48-, 72- and 96-hour median lethal concentrations (LC50) were calculated.

The No-Observed-Effect Concentration (NOEC) during the 96 hour exposure period was determined by visual observation. The NOEC is defined as the highest concentration tested at and below which there were no toxicant-related effects and mortality with respect to the control organisms. Additionally, the 96 hour LC0 and LC100 values were empirically determined by visual observation and are defined as the highest concentration causing no mortality and the lowest concentration causing 100% mortality during the exposure period, respectively.

There were no effects on mortality in the control or treated media.

Validity criteria fulfilled:
yes
Conclusions:
The test conducted according to the OECD guideline 203 and GLP resulted in an 96 h LC50 value of >100 mg/L and a NOEC of ≥100 mg/L for the effects of the test substance on the mortality of Oncorhynchus mykiss.
Endpoint:
short-term toxicity to fish
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
Please refer to the attached justification below and the overall justification for grouping of substances attached in IUCLID Section 13.
Reason / purpose:
read-across source
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality

Description of key information

LC50 (96 h) > 100 mg/L (nominal, OECD 203, Oncorhynchus mykiss) based on read across from CAS 98-13-5

Key value for chemical safety assessment

Additional information

Data on the toxicity of trichloro(4-methylphenyl)silane (CAS 701-35-9) towards fish are not available. Therefore in accordance with Regulation (EC) No. 1907/2006 Annex XI, 1.5 “Grouping of substances and read across” and in accordance with the read across assessment framework (RAAF, ECHA 2017) a read across from the analogue substance trichloro(phenyl)silane (CAS 98-13-5) has been performed. Details on the read across justification can be found in the attached justification in the respective target entry and in the overall justification for grouping of substances attached in IUCLID Section 13.

The study with the analogue substance trichloro(phenyl)silane (CAS 98-13-5) has been performed according to the OECD guideline 203 and GLP standards (2009). The single test item concentration of 100 mg/L was prepared with tetrahydrofuran as a solvent. Prior to test initiation the solution was stirred overnight. The test organism Oncorhynchus mykiss was exposed in a static testing regime to the mentioned test item concentration for 96 h. A control and a solvent control were run in parallel. No analytical monitoring was performed in this study, however analytical results from the toxicity study with aquatic invertebrates showed that hydrolysis takes place immediately and the silanol hydrolysis product remains then stable in the test medium during the experiment. No toxic effects on fish were observed. Therefore the LC50 (96 h) was > 100 mg/L (nominal). Since the substance hydrolyses rapidly (half-life < 1 min at pH 4-9 and 1.5 °C), the tested organism was exposed predominantly to the hydrolysis products.

On the basis of the read across data, no short term toxic effects towards fish are expected by trichloro(4-methylphenyl)silane (CAS 701-35-9).