Triethoxy(3-isocyanatopropyl)silane

Short-term toxicity to fish

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1993-10-11 to 1994-10-15

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 203 (Fish, Acute Toxicity Test)

Principles of method if other than guideline:

DIN 38412 Part 1; EG Guideline 92/69 C.1; OECD Guideline 203, 1984

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

The only treatment was sampled at the start of the test

Vehicle:

no

Details on test solutions:

A test medium was prepared at a nominal concentration of 1.0 g/L by mixing for 18 hours followed by filtration. Analysis of the medium showed it to contain 934 mg/L of the substance.

Test organisms (species):

Danio rerio (previous name: Brachydanio rerio)

Details on test organisms:

TEST ORGANISM

- Common name: Zebrafush

- 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

Test type:

semi-static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

96 h

Hardness:

10.7ºdH

Test temperature:

20-21ºC

pH:

7.8-8.4 in Control

8.2-9.3 in Treatment

Dissolved oxygen:

8.0-8.9 mg/L in Control

7.8-9.0 mg/L in Treatment

Salinity:

Not applicable

Nominal and measured concentrations:

Nominal concentrations: 0 (Control) and 1000 mg/L

Measured concentrations: 880 mg/l at 0 hours; 922/947 mg/l at 24 hours; 885 mg/l at 72 hours; average value of 934 mg/l (water  filtered initial solution).

Measured concentration in treated media: 934 mg/L

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.:

>= 934 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:

LC50

Effect conc.:

> 934 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:

- Mortality of control: 0

· Abnormal responses:  None reported

Reported statistics and error estimates:

No effects were observed in the test and therefore statistical analysis was not required.

Sublethal observations / clinical signs:

No effects were observed in Control or treated media.

Validity criteria fulfilled:

yes

Conclusions:

A 96-hour LC50 of >934 mg/L and NOEC of ≥934 mg/L have been determined for the effects of the test substance on mortality of Brachydabio rerio. It is likely that the test organisms were exposed predominantly to the hydrolysis products of the substance.

Description of key information

96 hour LC₅₀: >934 mg/l, mortality of Brachydanio rerio; equivalent to >579 mg/l as 3-aminopropylsilanetriol, read across from 3-aminopropyl(triethoxy)silane (CAS 919-30-2).

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

934 mg/L

Additional information

No data are available for the registered substance.

The isocyanate group is very rapidly hydrolysed to the corresponding amine (half-life <5 minutes at pH 7), and further hydrolysis of the alkoxy groups proceeds at a slower rate (half-life of 8.5 hours at pH 7 and 25°C).

Data are read across from 3-aminopropyl(triethoxy)silane (CAS 919-30-2), the amine which is formed very rapidly when the registered substance comes into contact with water / moisture.

A 96 hour LC₅₀of >934 mg/l (measured DOC concentration) (highest concentration tested) has been determined for the effects of 3-aminopropyl(triethoxy)silane (CAS 919-30-2) on mortality of Brachydanio rerio(tested as Danio rerio), in accordance with OECD Test Guideline 203 and in compliance with GLP (Hüls, 1994a).

The test substance is susceptible to hydrolysis and, due to the test media preparation (stirring for 18 hours) and exposure regime (semi-static), it is likely that the test organisms were predominantly exposed to the hydrolysis products of the substance. Concentration measured by DOC is non-specific, therefore the measured DOC concentration is likely to reflect the concentration of the hydrolysis products, 3-aminopropylsilanetriol and ethanol.

Because the measured DOC concentration is within 20 % of the nominal parent test substance concentration of 1000 mg/l, the results may be expressed in terms of concentration of the silanol hydrolysis product, 3-aminopropylsilanetriol, by applying a molecular weight correction: (MW of silanol = 137.21 / MW of parent = 221.37) * >934 mg/l = >579 mg/l.

Both the registration substance and the substance used as surrogate for read-across are susceptible to hydrolysis reaction of the alkoxysilane groups (to silanols) and to potential condensation reactions (described in Section 4.8 of IUCLID). During the tests with the read-across substance, pre-hydrolysis and filtration were used as part of media preparation. Analytical recoveries by DOC were high (within 20% of nominal). Models would suggest that irreversible condensation is unlikely for these silanol hydrolysis products at the concentrations relevant to the studies (PFA, 2016am).

These findings are supported by a 96 hour LC₅₀ in rainbow trout >100 mg/l, determined for 3-(trimethoxysilyl)propyl isocyanate (CAS 15396-00-6) (IBACON, 2003). For this substance the isocyanate group is very rapidly hydrolysed to the corresponding amine (half-life of minutes or less), and further hydrolysis of the alkoxy groups proceeds at a slower rate (half-life of 2.6 hours at pH 7 and 20-25 °C, estimated) to 3-aminopropylsilanetriol and methanol.