Dichloro(methyl)(phenyl)silane

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:

weight of evidence

Study period:

1996-11-11 to 1996-11-15

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

The study was conducted according to an appropriate EU method, and in compliance with GLP, and was considered to be reliability 2 (reliable with restrictions) due to the method of analysis being non-specific to the parent substance or the hydrolysis product.

Qualifier:

according to guideline

Guideline:

EU Method C.1 (Acute Toxicity for Fish)

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

- Dissolved organic carbon (DOC) concentrations were determined in a stability study conducted at nominal DOC concentrations of: 5.3, 26.7, 53.3 and 533 mg/L. Samples were taken for analyis 24, 48 and 72 hours after preparation. The DOC concentration of the stock solution used to prepare these concentrations was also determined at the start of the stability study in order to determine the nominal concentrations in the treatments and also on the same occasions during the study.

- Sample storage conditions before analysis: not described

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION

- Method: Nominal test substance concentrations of 34, 62, 107, 186 and 338 mg/L were prepared by dilution of a stock solution of 1000 mg/l. The stock solution was prepared by stirring for 18 h followed by filtration. The measured DOC concentration of the stock solution was equivalent to 564 mg/L of the test substance. Nominal test substance concentrations were based on the measured concentration in the stock solution.

- Controls: Dilution water

Test organisms (species):

Cyprinus carpio

Details on test organisms:

TEST ORGANISM

- Common name: Common carp

- Source: Bio International B.V., Someren, NL

- Length at study initiation (length definition, mean, range and SD): 2.0-3.0 cm

- Feeding during test: none

ACCLIMATION

- Holding conditions: The fish were held in 200 L of water in 300 L glass aquaria at a temperature of 20+/-2°C

- Acclimation period: at least 14 days

- Acclimation conditions: same as test

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

- Feeding frequency: Daily

- Health during acclimation (any mortality observed): The fish exhibit normal behaviour and are free from visible signs of disease at the start of the test. Mortality must not exceed 5% in the 7 day period prior to the test.

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Hardness:

12ºdH

Test temperature:

19-20.5ºC

pH:

2.0-8.1

Low pH values of 2.5 and 2.0 were measured in the 186 and 338 mg/L treatments at the start of the test. These treatments were not utilised in the test because they would not have been tolerated by the fish.

pH values in the other treatments (34-107 mg/L) ranged between 5.3 and 8.1

Dissolved oxygen:

84-99% ASV

Salinity:

not applicable

Nominal and measured concentrations:

Nominal concentrations: 0(Control), 34, 62, 107, 186 and 338 mg/L. The 186 and 338 mg/L treatments were not utilised in the test because they would not have been tolerated by the fish.

DOC concentrations determined in the stability study were stable after periods of 24, 48 and 72 hours (within +/-20% of nominal). The results are therefore interpreted with reference to nominal concentrations of the substance. However the substance is subject to hydrolysis and it is therefore likely that exposure will predominantly have been to hydrolysis products.

Details on test conditions:

TEST SYSTEM

- Test vessel:

- Type: open aquarium

- Material, size, headspace, fill volume: 20 L with 10 L of test medium

- Aeration: Continuous

- Renewal rate of test solution (frequency/flow rate): Daily

- No. of organisms per vessel: 10

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

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

- Biomass loading rate: 0.6 g/L


TEST MEDIUM / WATER PARAMETERS

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


OTHER TEST CONDITIONS

- Adjustment of pH: None

- Photoperiod: 16 h light/8 h dark


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Mortality after 24, 48, 72 and 96 h


TEST CONCENTRATIONS

- Spacing factor for test concentrations: 1.8

Reference substance (positive control):

no

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

> 107 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Remarks:

but exposure is to hydrolysis products

Basis for effect:

mortality (fish)

Duration:

96 h

Dose descriptor:

LC0

Effect conc.:

107 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Remarks:

but exposure is to hydrolysis products

Basis for effect:

mortality (fish)

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

>= 107 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

but exposure is to hydrolysis products

Basis for effect:

mortality (fish)

Details on results:

- Behavioural abnormalities: none reported

- Mortality of control: 0

- Other adverse effects control: none

- pH effects: ow pH values of 2.5 and 2.0 were measured in the 186 and 338 mg/L treatments at the start of the test. These treatments were not utilised in the test because they would not have been tolerated by the fish.

Reported statistics and error estimates:

There were no effects on mortality in the treatments that were not excluded on the grounds of low pH. Statistical analysis of the test results was therefore not required.

Sublethal observations / clinical signs:

Table 1. Test results

Mean initial measured test substance 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
34	0	0	0	0
62	0	0	0	0
107	0	0	0	0
186*	-	-	-	-
338*	-	-	-	-

*Treatments not continued because of low pH (≤2.5).

Table 2. Results of analysis of test media in stability study

Nominal concentration (mg/L)*	Measured concentration at start of study (mg/L)	Measured concentration after 24 hours (mg/L)	Measured concentration after 48 hours (mg/L)	Measured concentration after 72 hours (mg/L)
5.3	4.7	5.3	5.3	4.5
26.7	29.4	28.0	27.9	26.4
53.3	54.8	57.3	57.0	55.3
533	533	642	599	584
Stock solution	564	599	589	654

*Based on stock solution concentration at start of study

Validity criteria fulfilled:

yes

Conclusions:

A 96-hour LC50 value of >107 mg/L and NOEC of ≥107 mg/L have been determined for the effects of the test substance on mortality of Cyprinus carpio. The results are interpreted with reference to nominal concentrations of the test substance. However, due to the very rapid of the registered substance, it is very likely that the test organisms were exposed to the hydrolysis products of the substance rather than the parent substance.

Reference 2

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

1994-06-27 to 1994-07-01

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

Guideline study without restrictions. The study was conducted according to the appropriate OECD test guideline, in compliance with GLP and was considered to be reliability 1 (reliable without restrictions).

Qualifier:

according to guideline

Guideline:

EU Method C.1 (Acute Toxicity for Fish)

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

- Concentrations: 60, 120, 250, 500 and 1000 mg/L.

- Sampling method: Samples of each batch of fresh test media were taken for analyis at the start of the test and after 24, 48 and 72 hours. A sample of old test medium was also taken on one occasion after 24 hours in order to assess stability.

- Sample storage conditions before analysis: not described

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION

- Method: Nominal test concentrations of 60, 120, 250, 500 and 1000 mg/L were prepared by dilution of a stock solution. The stock solution was prepared by stirring for 18 h followed by filtration.

- Controls: Dilution water

Test organisms (species):

Danio rerio (previous name: Brachydanio rerio)

Details on test organisms:

TEST ORGANISM

- Common name: Zebrafish

- Source: West aquarium, Bad Lauterberg, Germany

- Length at study initiation (length definition, mean, range and SD): 3.0 cm +/-0.5 cm

- Feeding during test: none

ACCLIMATION

- Acclimation period: at least 14 days

- Acclimation conditions: same as test

- Type and amount of food: 1% of body weight

- Feeding frequency: Daily

- Health during acclimation (any mortality observed): The fish exhibit normal behaviour and are free from visible signs of disease at the start of the test. Mortality must not exceed 5% in the 7 day period prior to the test.

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Hardness:

12ºdH

Test temperature:

20-22ºC

pH:

7.7-8.4

Dissolved oxygen:

66-102% ASV

Salinity:

not applicable

Nominal and measured concentrations:

Nominal concentrations: 0(Control), 60, 120, 250, 500 and 1000 mg/L

Mean measured initial concentrations: 0(Control), 47, 101, 211, 416 and 863 mg/L

The measured concentration declined by between 8 and 26% over a 24 hour period.

The test results are interpreted with reference to mean measured initial concentrations

Details on test conditions:

TEST SYSTEM

- Test vessel:

- Type: open aquarium

- Material, size, headspace, fill volume: 30 L with 10 L of test medium

- Aeration: Continuous

- Renewal rate of test solution (frequency/flow rate): Daily

- No. of organisms per vessel: 10

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

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

- Biomass loading rate: 0.13 g/L


TEST MEDIUM / WATER PARAMETERS

- Source/preparation of dilution water: Potable water from Gelsenwasser AG, according to the guideline


OTHER TEST CONDITIONS

- Adjustment of pH: None

- Photoperiod: 16 h light/8 h dark


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Mortality after 24, 48, 72 and 96 h


TEST CONCENTRATIONS

- Spacing factor for test concentrations: 1.8

Reference substance (positive control):

no

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

574 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Remarks:

but exposure is to hydrolysis products

Basis for effect:

mortality (fish)

Remarks on result:

other: 416-863

Duration:

96 h

Dose descriptor:

LC0

Effect conc.:

211 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Remarks:

but exposure is to hydrolysis products

Basis for effect:

mortality (fish)

Details on results:

- Behavioural abnormalities: none reported

- Mortality of control: 0

- Other adverse effects control: none

Reported statistics and error estimates:

The LC50 values were obtained from a plot of log concentration versus percentage mortality. The confidence interval was defined as the concentrations bounding the LC50 value. The LC0 value was obtained directly from the raw data.

Sublethal observations / clinical signs:

Table 1. Test results

Mean initial measured test substance 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
47	0	0	0	0
101	0	0	0	0
211	0	0	0	0
416	0	0	0	10
863	10	100	100	100

Table 2. Results of analysis of test media

Nominal test substance concentration (mg/L)	Measured concentration in fresh medium at start of test (mg/L)	Measured concentration in old medium after 24 hours (mg/L)	Measured concentration in fresh medium at 24 hours (mg/L)	Measured concentration in fresh medium at 48 hours (mg/L)	Measured concentration in fresh medium at 72 hours (mg/L)	Mean initial measured concentration at 0, 24, 48 and 72 hours (mg/L)
60	47	35	52	44	45	47
120	101	81	108	96	99	101
250	200	177	240	200	203	211
500	423	357	462	380	399	416
1000	806	742	919	-	-	863

Validity criteria fulfilled:

yes

Conclusions:

A 96-hour LC50 value of 574 mg/L and a 96-h LC0 value of 211 mg/L have been determined for the effects of the test substance on mortality of Brachydanio rerio. The results are interpreted with reference to mean measured concentrations of the test substance based on dissolved organic carbon. However it is likely that the test organisms were primarily exposed to the hydrolysis products of the substance.

Reference 3

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

2009-09-29 to 2009-10-03

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

The study was conducted according to an appropriate OECD test guideline, and in compliance with GLP, and was considered to be reliability 1 (reliable without restrictions).

Qualifier:

according to guideline

Guideline:

OECD Guideline 203 (Fish, Acute Toxicity Test)

GLP compliance:

yes (incl. QA statement)

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 minute 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 - 15.5ºC

pH:

7.2 - 7.5

Dissolved oxygen:

8.9 - 10.7 mg/L

Salinity:

Not applicable

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 liter 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 (fish)

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

>= 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

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.

Sublethal observations / clinical signs:

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

Validity criteria fulfilled:

yes

Conclusions:

A 96-hour LC50 value of >100 mg/L and a 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 primarily exposed to the hydrolysis products of the substance.

Description of key information

Short-term toxicity to fish:

WoE 96-hour LC₅₀ >107 mg/l (nominal) (highest concentration tested) (EU Method C.1 (Acute Toxicity for Fish)), read-across from an analogous/structurally related substance, dichloro(3-chloropropyl)methylsilane (CAS 7787-93-1). The observations in this study are attributed to the exposure of test organisms to the hydrolysis products in the test system. The result may be expressed in terms of concentration of the hydrolysis product: 96-hour LC₅₀ >86 mg/l as (3-chloropropyl)(methyl)silanediol.

WoE 96-hour LC₅₀ 574 mg/l (measured DOC concentration) (EU Method C.1 (Acute Toxicity for Fish)), read-across from an analogous/structurally related substance, (3-chloropropyl)diethoxymethylsilane (CAS 13501-76-3). The observations in this study are attributed to the exposure of test organisms to the hydrolysis products in the test system (3-chloropropyl)(methyl)silanediol and ethanol. The result is not expressed in terms of concentration of the hydrolysis product by applying a molecular weight correction, because the result is reported in terms of measured DOC concentration.

WoE 96-hour LC₅₀ >100 mg/l (nominal) (highest concentration tested) (Test guideline OECD 203 (Fish, acute toxicity test)), read-across from an analogous/structurally related substance, trichloro(phenyl)silane (CAS 98-13-5). The observations in this study are attributed to the exposure of test organisms to the hydrolysis products in the test system. The result may be expressed in terms of concentration of the hydrolysis product: 96-hour LC₅₀ >74 mg/l as phenylsilanetriol.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

574 mg/L

Additional information

No data are available for the registration substance dichloro(methyl)(phenyl)silane (CAS 149-74-6), however data are available from the related substances dichloro(3-chloropropyl)methylsilane (CAS 7787-93-1), 3-chloropropyl(diethoxy)methylsilane (CAS 13501-76-3) and trichloro(phenyl)silane (CAS 98-13-5). All substances have relevant analogous silanol hydrolysis products, methylphenylsilanediol, (3-chloropropyl)(methyl)silanediol and phenylsilanetriol. The other hydrolysis products are hydrochloric acid and ethanol. In the tests with dichloro(3-chloropropyl)methylsilane (CAS 7787-93-1), (3-chloropropyl)diethoxymethylsilane (CAS 13501-76-3) and trichloro(phenyl)silane (CAS 98-13-5), the observations are attributed to the exposure of test organisms to the silanol hydrolysis products (3-chloropropyl)(methyl)silanediol and phenylsilanetriol in the test system. There is no basis to expect that hydrochloric acid or ethanol significantly influenced the results of the tests. The toxicity of hydrochloric acid and ethanol is discussed further in the ecotoxicological information overview endpoint summary (additional information).

 

A 96-hour LC₅₀ value of >107 mg/l has been determined for the effects of dichloro(3-chloropropyl)methylsilane (CAS 7787-93-1) on mortality of Cyprinus carpio. The results are determined in terms of nominal concentrations of the test substance. However, due to the rapid hydrolysis rates it is very likely that the test organisms were exposed to the hydrolysis products. The results may be expressed in terms of concentration of the hydrolysis product, (3-chloropropyl)(methyl)silanediol, by applying a molecular weight correction: (MW of silanol = 154.67 / MW of parent = 191.56) * [CONCENTRATION OF PARENT = >107 mg/l] = >86 mg/l.

 

A 96-hour LC₅₀ value of 574 mg/l has been determined for the effects of (3-chloropropyl)diethoxymethylsilane (CAS 13501-76-3) on mortality of Danio rerio. The results determined in terms of measured concentrations of dissolved organic carbon (DOC). Due to the hydrolysis rate of the test substance (9.5 hours at pH 7) and test media preparation methods (stirring for 18 hours prior to addition of test organisms), it is very likely that the test organisms were exposed to the hydrolysis products (3-chloropropyl)(methyl)silanediol and ethanol.

 

A 96-hour LC₅₀ value of >100 mg/l has been determined for the effects of trichloro(phenyl)silane (CAS 98-13-5) on mortality of Oncorhynchus mykiss. The results are determined in terms of nominal concentrations of the test substance. It is likely that the test organisms were primarily exposed to the hydrolysis products of the substance phenylsilanetriol and hydrochloric acid. The results may be expressed in terms of concentration of the hydrolysis product, phenylsilanetriol, by applying a molecular weight correction: (MW of silanol = 156.21 / MW of parent = 211.55) * [CONCENTRATION OF PARENT = >100 mg/l] = >74 mg/l. This data indicates that the phenyl group does not contribute to the toxicity of the substance. 

All tests are interpreted as weight of evidence.