Trichlorosilane

Short-term toxicity to fish

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2004-05-06 to 2004-05-10

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Guideline study with GLP but no analysis of exposure concentrations

Qualifier:

according to guideline

Guideline:

OECD Guideline 203 (Fish, Acute Toxicity Test)

Principles of method if other than guideline:

ASTM. 2002. Standard practice for conducting acute toxicity tests with fishes, macroinvertebrates and amphibians. Standard E729-96. American Society for Testing and Materials, 100 Barr Harbor Drive, West Conshohocken, PA 19428.

OECD. 1992. Guideline for Testing of Chemicals. Fish Acute Toxicity Test. Guideline #203. Adopted 17 July 1992.

U.S. EPA. 1975. Methods for Acute Toxicity Tests with Fish, Macroinvertebrates and Amphibians. Ecological Research Series (EPA-660/3-75-009). 61 pp.

GLP compliance:

yes

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)

- Method: A 100 mg a.i./L stock. solution was prepared by adding 4.3 mL of trimethoxysilane to 40 L of dilution water (based on a purity of 97.1% and a density of 0.957 g/mL). The solution was mixed overnight and was observed to be clear and colorless with no undissolved test substance visible following mixing. Each test concentration was prepared by adding the appropriate amount of the 100 mg a.i./L stock solution to the test vessel and bringing it to a final volume of 15 L with dilution water.

Test organisms (species):

Oncorhynchus mykiss (previous name: Salmo gairdneri)

Details on test organisms:

TEST ORGANISM

- Common name: Rainbow trout

- Source: Test organisms were obtained from Trout Lodge, Sumner, Washington. 

- Length at study initiation (length definition, mean, range): 40 mm (range 38 to 42 mm)

- Weight at study initiation (mean and range): 0.62 g (range 0.47 to 0.74 g)

- Holding conditions: during the 14-day period prior to testing, rainbow trout were held in a 500-L fiberglass tank under a photoperiod of 16 hours light and 8 hours dark. The temperature in the holding tank ranged from 13 to 15 °C during this 14-day period. The water which flowed into the fish holding tank and was characterized as having a total hardness and alkalinity as CaCO3 of 36 mg/L and 24 mg/L, respectively, a pH of 7.5, and a specific conductivity of 130 umhos/cm. The fish were fed a dry commercial flaked fish food and brine shrimp, ad libitum,daily. Fish were not fed during the 48-hour period prior to test initiation or during the exposure period.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Hardness:

Total hardness and alkalinity: 44 mg/L and 28 mg/L as CaCO3

Test temperature:

13 to 15 ºC

pH:

6.1-7.0

Dissolved oxygen:

5.1-9.8 mg/L

Salinity:

not applicable

Nominal and measured concentrations:

Nominal concentrations: 0 (Control), 13, 22, 36, 60 and 100 mg a.i./L

Details on test conditions:

TEST SYSTEM

- Test vessel: The toxicity test was conducted in 20.8-L aquaria constructed entirely of glass and silicone sealant impartially placed in a temperature-controlled water bath designed to maintain exposure solution temperatures at 14± 1°C. A single aquarium was established for each treatment level and the control with the aquaria containing 15 L of test solution. Gentle, oil-free aeration was initiated at the 48-hour observation interval to raise and maintain dissolved oxygen levels at or above 60% of saturation.

- Test design (number of replicates, individuals per replicate, concentrations): Ten rainbow trout were impartially selected and distributed to each exposure vessel. Fish were added two at a time to each test vessel until each test vessel contained ten fish. A total of 10 organisms were exposed to each treatment level and the control.


TEST MEDIUM / WATER PARAMETERS

- Source/preparation of dilution water: Laboratory well water.

- Dilution water chemistry (hardness, alkalinity, pH, TOC): The dilution water had a total hardness and alkalinity as CaCO3 of 44 mg/L and 28 mg/L, respectively, a pH of 7.6 and a specific conductivity of 130 umhos/cm. The TOC concentration of the dilution water source was 0.40 mg/L for the month of May 2004.

- Water chemistry in test (D.O., pH), in the control, and at least one concentration where effects were observed: The dilution water control vessel had a measured DO concentration of 9.7 mg/L at test initiation and 9.4 mg/L at test termination. The pH measured in the dilution water control was 6.8 at test initiation and test termination.


OTHER TEST CONDITIONS

- Lighting (quality, intensity, and periodicity): The test area was illuminated with fluorescent bulbs at an intensity range of 32 to 57 footcandles at the solutions' surface. The test area received a regulated photoperiod of l6 hours of light and 8 hours of darkness. Sudden transitions from light to dark and vice versa were avoided. Light intensity was measured once during the test.


EFFECT PARAMETERS MEASURED: Mortality

TEST CONCENTRATIONS

- Spacing factor for test concentrations: 1.6

- Range finding study

- Test concentrations: 1, 10 and 100 mg/L

- Results used to determine the conditions for the definitive study: 20% mortality in 100 mg/L after 24 hours. No effects in other treatments or Control

Reference substance (positive control):

no

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

>= 100 mg/L

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

> 100 mg/L

Details on results:

- Mortality of control: 0

Reported statistics and error estimates:

No effects were observed in the test. The results were therefore not subject to statistical analysis

Sublethal observations / clinical signs:

Table 1. Test results

Nominal concentration (mg/L)	Percentage mortality after 96 hours
0 (Control)	0
13	0
22	0
36	0
60	0
100	0

24-, 48-, 72-, and 96-hour LC50: > 100 mg a.i./L.

NOEC through 96 hours 100 mg a.i./L.

The highest concentration producing 0% mortality was 100 mg
a.i./L.  The lowest concentration producing 100% mortality
was > 100 mg a.i./L.

Biological observations:

- Number of mortalities as compared to the number exposed:
Number of mortalities: 0, Number exposed: 60 (includes
control)

- Concentration response with 95% confidence limits: > 100
mg a.i./ L (empirically estimated), corresponding 95%
confidence intervals could not be calculated.

- Cumulative mortality: 0% mortality was observed among fish
exposed to all treatment levels tested.

- Was control response satisfactory (yes/no/unknown): Yes.

No mortality or adverse effects were observed among fish
exposed to the control.

Validity criteria fulfilled:

yes

Conclusions:

A 96-hour LC50 of >100 mg/L and NOEC of ≥100 mg/L have been determined for the effects of the test substance on mortality of Oncorhynchus mykiss. It is likely that the test organisms were exposed to the hydrolysis products of the substance.

Reference 2

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

1993-10-11 to 1993-10-15

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EU Method C.1 (Acute Toxicity for Fish)

Version / remarks:

Cited as Directive 92/69/EEC, C.1

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

Samples of freshly prepared test media were taken at the start of each successive 24 hour exposure period (0, 24, 48 and 72 hours). Samples of old test medium were taken at the end of the first 24-hour exposure period in order to assess the stability of the exposure concentrations.

Vehicle:

no

Details on test solutions:

A stock solution was prepared by adding the test substance to potable water at the rate of 1 g/L. After mixing the medium was filtered and the aqueous phase used as the test medium. The average measured Dissolved Organic Carbon Concentration determined in the fresh test medium over the course of the test (245 mg/L) was used as the basis for expressing the test results.

Test organisms (species):

Danio rerio (previous name: Brachydanio rerio)

Details on test organisms:

TEST ORGANISM

- Common name: Zebrafish

- Source: West Aquarium, Bad Lauterburg, Germany

- Length at study initiation: 3.0+/-0.5 cm

- Feeding during test: none


ACCLIMATION

- Acclimation period: 14-days

- Acclimation conditions: same as test

- Type and amount of food: Tetramin® at 1% of body weight

- Feeding frequency: Daily

- Health and pre-treatment: The specimens were pre-conditioned (treatment: 3x per week with malachite green) and subjected to a 14-day quarantine.  They were used in testing only after this treatment.  Only specimens displaying normal behavior at the beginning of the test and free of obvious disease were used in the study.  Fish were not fed during the test.       

Test type:

semi-static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

96 h

Hardness:

10.7 ºdH

Test temperature:

20+/-1ºC

pH:

7.5-8.4

Dissolved oxygen:

4.3-8.9 mg/L (the low value of 4.3 mg/L did not affect the outcome of the test)

Salinity:

Not applicable

Nominal and measured concentrations:

Nominal loading used to prepare test medium: 1000 mg/L

Mean measured DOC concentration in the test medium: 245 mg/L

The mean measured DOC concentration has been used as the basis for expressing the test results.

Details on test conditions:

TEST SYSTEM

- Test vessel: 20 litre aquarium

- Type (delete if not applicable): open

- Aeration: Yes, continuous

- Renewal rate of test solution: daily

- No. of organisms per vessel: 10

- No. of vessels per concentration (replicates): 1

- No. of vessels per control (replicates): 1


TEST MEDIUM / WATER PARAMETERS

- Source/preparation of dilution water: Potable water from Gelsenwasser AG


OTHER TEST CONDITIONS

- Adjustment of pH: No

- Photoperiod: 16 hours light, 8 hours dark


EFFECT PARAMETERS MEASURED: Daily mortalities


TEST CONCENTRATIONS

- Spacing factor for test concentrations: Limit test

Reference substance (positive control):

no

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

>= 245 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

> 245 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Details on results:

- Mortality of control: 0

Reported statistics and error estimates:

There were no mortalities observed in the test and therefore statistical analysis of the results was not required.

Sublethal observations / clinical signs:

Table 1. Results of analysis of test media

Nominal loading of test substance (mg/L)	Measured DOC concentration in fresh medium at start of test (mg/L)	Measured DOC concentration in old medium after 24 hours (mg/L)	Measured DOC concentration in fresh medium after 24 hours (mg/L)	Measured DOC concentration in fresh medium after 48 hours (mg/L)	Measured DOC concentration in fresh medium after 72 hours (mg/L)	Mean measured DOC concentration (mg/L)
1000	316	247	227	281	156	245

Table 2. Test results

Mean measured DOC concentration (mg/L)	Percentage mortality after 24 hours	Percentage mortality after 48 hours	Percentage mortality after 72 hours	Percentage mortality after 96 hours
0 (Control)	0	0	0	0
245	0	0	0	0

Validity criteria fulfilled:

yes

Conclusions:

A 96-hour LC50 of >245mg/L and a NOEC of ≥245 mg/L have been determined for the effects of the test substance on mortality of Brachydanio rerio. It is likely that the test organisms were exposed to the hydrolysis products of the substance.

Description of key information

Short-term toxicity to fish: 96-hour LC₅₀: >100 mg/l, mortality of Oncorhynchus mykiss; equivalent to >79 mg/l as monosilicic acid, read across from trimethoxysilane (CAS 2487-90-3).

Additional information

There are no reliable short-term data available for trichlorosilane (CAS 10025-78-2) therefore good quality data from an appropriate structural analogue, trimethoxysilane (CAS 2487-90-3), have been read across. The substances share the same silanol hydrolysis product, monosilicic acid. The other hydrolysis products are hydrogen chloride for trichlorosilane (CAS 10025-78-2) and methanol for trimethoxysilane (CAS 2487-90-3).

A 96-hour LC₅₀ of >100 mg/l (nominal concentration) (highest concentration tested) has been determined for the effects of trimethoxysilane (CAS 2487-90-3) on mortality of Oncorhynchus mykiss, in accordance with OECD Test Guideline 203 and in compliance with GLP (Springborn Smithers, 2004a).

The test substance is susceptible to hydrolysis and, due to the test media preparation (stirring overnight) and exposure regime (semi-static), it is likely that the test organisms were predominantly exposed to the hydrolysis products of the substance, monosilicic acid and methanol.

The results may be expressed in terms of concentration of the hydrolysis product, monosilicic acid, by applying a molecular weight correction: (MW of silanol = 96.10 / MW of parent = 122.20) * >100 mg/l = >79 mg/l.  

 

Supporting data have also been read across from tetraethyl orthosilicate (CAS 78-10-4), which hydrolyses rapidly to monosilicic acid and ethanol:

 

A 96-h LC₅₀ value of >245 mg/l (mean measured TOC) (highest concentration tested) has been determined for the effects of tetraethyl orthosilicate (CAS 78-10-4) on mortality of Danio rerio (Hüls, 1993) in accordance with test guideline EU method C.1 and in compliance with GLP.

In view of the test media preparation method/exposure regime it is likely that the test organisms were exposed predominantly to the hydrolysis products of the tested substance.

The results may be expressed in terms of concentration of the hydrolysis product, monosilicic acid, by applying a molecular weight correction: (MW of silanol = 96.1 / MW of parent = 208.33) * >245 = >113 mg/l. 

Refer to IUCLID Section 6, CSR Section 7, and the ecotoxicity RAAF report attached in IUCLID Section 13 or as an Annex in the CSR, for further discussion of the approach to chemical safety assessment and justification for read across.