N-(dimethylvinylsilyl)-1,1-dimethyl-1-vinylsilylamine

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:

1994-03-21 to 1994-03-25

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

The study was conducted according to an appropriate EU method, and 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)

Version / remarks:

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

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

- Concentrations: All concentrations at the start of the test and after 24, 48, 72 and 96 hours in fresh and/or old media as applicable

- Sampling method: Not reported

- Sample storage conditions before analysis: Not reported

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION

- Method: Test media prepared by mixing for 18 h followed by filtration.

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 or not): yes

- Type and amount of food: TetraMin® 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 t
est.

Test type:

semi-static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

96 h

Hardness:

220 mg/L as CaCO3

Test temperature:

20ºC

pH:

7.8-8.7

Dissolved oxygen:

78-99% ASV

Salinity:

Not applicable

Nominal and measured concentrations:

Nominal test concentrations: 0 (Control), 120, 180, 250, 350 and 500 mg/L

Mean measure concentrations: 0, 25, 41, 56, 77 or 110 mg/L.

Details on test conditions:

Ten fish per 20 L test aquarium were exposed for 96 hrs to each of the treatments.

Dilution water was Tap water (Gelsenwasser AG)

According to an analysis certificate, the TOC background value is 3  mg/l.

Reference substance (positive control):

no

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

56 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

other: test substance hydrolysis products

Basis for effect:

mortality (fish)

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

88 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

other: tst substance hydrolysis products

Basis for effect:

mortality (fish)

Duration:

96 h

Dose descriptor:

LC100

Effect conc.:

110 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

other: test substance hydrolysis products

Basis for effect:

mortality (fish)

Details on results:

- Mortality of control: 0%

Reported statistics and error estimates:

The LC50 was determined graphically from a plot of mortality versus log mean test substance concentration

Sublethal observations / clinical signs:

Table 1. Test results

Nominal test substance concentration (mg/L)	Mean measured concentration over the test (mg/L)	Percentage mortality at end of test
0 (Control)	-	0
120	25	0
180	41	0
250	56	10
350	77	20
500	110	100

    

Validity criteria fulfilled:

yes

Conclusions:

A 96 LC50 value of 88 mg/L and a NOEC of 56 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 predominantly exposed to the hydrolysis products of the substance.

Reference 2

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

2004-03-15 to 2004-03-19

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 203 (Fish, Acute Toxicity Test)

Qualifier:

according to guideline

Guideline:

EPA OPPTS 850.1075 (Freshwater and Saltwater Fish Acute Toxicity Test)

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

- Concentrations: Negative Control, 63, 125, 250, 500 and 1000 mg/L

- Sampling method: Measurement of test concentrations in each test chamber at test initiation, on Day 1 (old solutions) and at test termination :

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION

- Method: Direct addition of test article to dilution water

- Controls: Dilution water

- Chemical name of vehicle (organic solvent, emulsifier or dispersant): No organic solvent

Test organisms (species):

Oncorhynchus mykiss (previous name: Salmo gairdneri)

Details on test organisms:

TEST ORGANISM

- Common name: Rainbow trout

- Age at study initiation (mean and range, SD): 77 days

- Length at study initiation: 5.9 cm (Range 5.5 to 6.3 cm)

- Weight at study initiation: 1.7 g (Range 1.4 to 2.3 g)

ACCLIMATION

- Acclimation period: 2 weeks prior to the test.

- Acclimation conditions: same as test

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Post exposure observation period:

None

Hardness:

122 mg/L as CaCO3

Test temperature:

11.3 - 12.2 ºC

pH:

8.3-8.7

Dissolved oxygen:

>8.3 mg/L (>77% saturation)

Salinity:

Not applicable

Nominal and measured concentrations:

Nominal concentrations: Negative Control, 63, 125, 250, 500 and 1000 mg/L in dilution water

Measured concentrations:
Method of Calculating Mean Arithmetic mean
Statistical methods: Binomial Probability, Probit Method

Details on test conditions:

TEST SYSTEM

- Test vessel:

- Type: open

- Material, size, headspace, fill volume: 38-L or 54-L stainless steel aquaria containing 30-L of test solution

- Renewal rate of test solution: Daily renewal

- No. of organisms per vessel: 10

- No. of vessels per concentration (replicates): 2

- No. of vessels per control (replicates): 2

- Biomass loading rate: 0.3-0.5 g/L


TEST MEDIUM / WATER PARAMETERS

- Source/preparation of dilution water: Well water

- Alkalinity: 180 mg/L as CaCO3

- Conductivity: 270 mhos/cm

- Culture medium different from test medium: no

- Intervals of water quality measurement: daily


OTHER TEST CONDITIONS

- Adjustment of pH: no


EFFECT PARAMETERS MEASURED: Mortality observed daily


TEST CONCENTRATIONS

- Spacing factor for test concentrations: 2

Reference substance (positive control):

no

Duration:

24 h

Dose descriptor:

LC50

Effect conc.:

> 949 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Remarks on result:

other: not calculable

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

523 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Remarks on result:

other: 250-949

Duration:

72 h

Dose descriptor:

LC50

Effect conc.:

476 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Remarks on result:

other: 402-565

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

271 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Remarks on result:

other: 128-481

Duration:

96 h

Dose descriptor:

LC0

Effect conc.:

128 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

128 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Details on results:

Biological observations: After 96 hours of exposure, all surviving fish appeared normal.

Lowest test substance concentration causing 100% mortality: 481 mg/L

Mortality of controls: 5%

Abnormal responses: Surfacing, loss of equilibrium, erratic swimming and lying on bottom

Any observations, such as precipitation that might cause a difference between measured and nominal values: All test solutions appeared clear and colourless.

Sublethal observations / clinical signs:

Table 1. Cumulative mortality:  
Mean Measured 
Concentration    Number Dead/Number Exposed (hours)
(mg/L)             0     24    48    72    96 
0                  0/20  0/20  0/20  0/20  1/20  
65                 0/20  0/20  0/20  0/20  0/20
128                0/20  0/20  0/20  0/20  0/20
250                0/20  0/20  0/20  1/20  8/20
481                0/20  0/20  8/20  9/20  20/20
949                0/20  6/20  20/20 20/20 20/20

Validity criteria fulfilled:

yes

Conclusions:

A 96-hour LC50 of 271 mg/L and a NOEC of 128 mg/L have been determined for the effects of the test substance on mortality of Oncorhynchus mykiss based on mean measured concentrations.

Description of key information

(WoE) Short-term toxicity to fish: 96 hr LC₅₀ 271 mg/l (measured) (OECD 201), read-across from an analogous substance, trimethylsilanol (CAS 1066-40-6).  

(WoE) Short-term toxicity to fish: 96 hr LC₅₀ 88 mg/l (measured) (OECD 201), read-across from a structurally related substance, 1,1,1,3,3,3-hexamethyldisilazane (CAS 999-97-3). The LC₅₀ is equivalent to 49 mg/l when expressed in terms of the silanol hydrolysis product, trimethylsilanol and 9.3 mg/l in terms of NH₃.

(supporting) Short-term toxicity to fish: 96 hr LC₅₀ 191 mg/l (nominal) (OECD 201), read-across from an analogous, trimethoxy(vinyl)silane (CAS 2768-02-7). The LC₅₀ is equivalent to 137 mg/l when expressed in terms of the silanol hydrolysis product, vinylsilanetriol

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

271 mg/L

Additional information

There are no reliable short-term fish toxicity data for N-(dimethylvinylsilyl)-1,1-dimethyl-1-vinylsilylamine, therefore good quality data have been for the effects of read-across substances: 1,1,1,3,3,3-hexamethyldisilazane (CAS 999-97-3) and trimethylsilanol (CAS 1066-40-6). The read-across is based on structural similarity and production of ammonia, and structural similarity and log K_ow of the silanol hydrolysis product of the registered substance, respectively. In view of this approach to read-across the data are considered together to form a Weight of Evidence approach.

 

In addition, supporting data are presented for trimethoxy(vinyl)silane (CAS 2768-02-7) to provide evidence of low toxicity of the vinyl group.

 

96-h LC50 values of 88, 271 and 191 mg/l and NOECs of 56, 128 and 100 mg/l (measured, measured and nominal respectively) have been determined for the effects of the read-across substances 1,1,1,3,3,3-hexamethyldisilazane (CAS 999-97-3), trimethylsilanol (CAS 1066-40-6) and trimethoxy(vinyl)silane (CAS 2768-02-7) respectively, on mortality of Brachydanio rerio, Oncorhynchus mykiss and Oncorhynchus mykiss respectively.

 

The data on trimethylsilanol (CAS 1066-40-6) are used to derive the PNEC for the silanol hydrolysis product, whereas the data for 1,1,1,3,3,3-hexamethyldisilazane (CAS 999-97-3) are used to establish the classification and labelling of the registered substance due to the presence of the ammonia hydrolysis product, which drives toxicity. The PNECs for ammonia are derived based on literature data.

 

Trimethylsilanol (TMS, CAS 1066-40-6) has the potential to condense to form hexamethyldisiloxane (HMDS, CAS 107-46-0), which may be present at low levels in the test system. HMDS is classified as Aquatic Acute 1 H400 and Aquatic Chronic 2 H411^[1] and therefore its presence has the possibility to impact the results. However, the estimated concentrations of HMDS in the tests with trimethylsilanol are low. Therefore the effects seen in the short-term toxicity to fish study, such as 40% mortality at 250 mg/l test concentration, may be attributable to TMS alone and the study is considered to be conservative and reliable for the purpose of this assessment.

 

In view of the exposure regime and the fast hydrolysis rates of 1,1,1,3,3,3-hexamethyldisilazane (CAS 999-97-3) and trimethoxy(vinyl)silane (CAS 2768-02-7), it is likely that the test organisms were exposed predominantly to the hydrolysis products of the tested substances.

1,1,1,3,3,3-Hexamethyldisilazane (CAS 999-97-3)

The results may be expressed in terms of concentration of the hydrolysis product, trimethylsilanol, by applying a molecular weight correction: (MW of silanol = 90.2 / MW of parent= 161.4) * 88 mg/l = 49 mg/l. The results may also be expressed in terms of ammonia (NH₃), by applying a molecular weight correction: (MW of ammonia 17.03 / MW parent 161.4) * 88 mg/l = 9.3 mg/l. However, data with 1,1,1,3,3,3-hexamethyldisilazane are read across for the purpose of classification and labelling and the relevant values are those determined in terms of the parent substance.

Trimethoxy(vinyl)silane (CAS 2768-02-7)

The results may be expressed in terms of concentration of the hydrolysis product, vinylsilanetriol, by applying a molecular weight correction: (MW of silanol = 106.15 / MW of parent = 148.24) * 191 mg/l = 131 mg/l. This value is used as supporting evidence of the lack of effects of dimethylvinylsilanol without further correction.

 

 

Refer to the discussion in the Section 6 endpoint summary (Section 7.0 of CSR) for further discussion of the approach to chemical safety assessment for this registration substance. Please refer to Section 13 of IUCLID for the read-across justification.

 

Ammonia:

Reliable short-term test results are available for ammonia sourced from the Environment Agency Proposed EQS for Water Framework Directive Annex VIII Substances: Ammonia (un-ionised) 2007. The most sensitive species to ammonia was found to be fish (Oncorhynchus gorbusha- pink salmon), with an LC50 of 0.083 mg un-ionised NH₃/L (Rice and Bailey, 1980).

^[1]https://echa.europa.eu/information-on-chemicals/cl-inventory-database/-/discli/notification-details/32082/948794