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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Ecotoxicological information

Endpoint summary

Administrative data

Description of key information

Additional information

The registered substance is part of a group of organosilicon substances. Additional information is given in a supporting report (PFA, 2013a) attached in Section 13 of the IUCLID 5 dossier.

READ-ACROSS JUSTIFICATION

In order to reduce animal testing read-across is proposed to fulfil up to REACH Annex IX requirements for the registered substance from substances that have similar structure and physico-chemical properties. Ecotoxicological studies are conducted in aquatic medium or in moist environments; therefore the hydrolysis rate of the substance is particularly important since after hydrolysis occurs the resulting product has different physico-chemical properties and the structure is altered.

In the following paragraphs the read-across approach for [3-(triethoxysilyl)propyl]urea (CAS 23779-32-0) is assessed for each surrogate substance taking into account structure, hydrolysis rate and physico-chemical properties.

 

·        Read-across from Ureidopropyltrialkoxysilane, mixed methoxy and ethoxy esters (116912-64-2) to [3 -(triethoxysilyl)propyl]urea:

The registered substance, [3-(triethoxysilyl)propyl]urea (CAS 23779-32-0) contain an ureidopropyl silane group with a ethoxy moiety, respectively. The related substance ureidopropyltrialkoxysilane, mixed methoxy and ethoxy esters (CAS 116912-64-2) is a multi-constituent substance, with the submission substance being one of the constituents. All constituents of ureidopropyltrialkoxysilane, mixed methoxy and ethoxy esters (CAS 116912-64-2), including the submission substance, undergo hydrolysis reaction with half-lives between <2.4 to 20.6 h.

Therefore, the hydrolysis products of these substances are also of relevance in the chemical safety assessment. The substances hydrolyse to the common silanol hydrolysis product, 3-Ureidopropylsilanetriol. The non-silanol hydrolysis products are ethanol and/or methanol, respectively.

Apart from the same hydrolysis product, other phys.-chem. data suppose that similar behaviour can also be expected for the parent constituents, as their molecular weights and log Kow are comparable.

Short-term measured data for Ureidopropyltrialkoxysilane, mixed methoxy and ethoxy esters were available for fish, invertebrates and algae.In an acute fish toxicity test according OECD 203 and GLP (NOTOX, 2000d), the 96 h LC50 for carp Cyprinus carpio exposed ureidopropyltrialkoxysilane, mixed methoxy and ethoxy esters was >100 mg/l in a static system. A 48 h EC50 value of > 100 mg/l has been determined for the effects on mobility of Daphnia magna (OECD 202, NOTOX, 2000e) and 72 hour EC50 value of > 220 mg/l and NOEC of 10 mg/l have been determined for the effects on growth rate ofScenedesmus subspicatus (OECD 201, NOTOX, 2000f).

 

 

·        Considerations on the non-silanol hydrolysis products:

Methanol and ethanol are well characterised in the public domain literature and are not hazardous at the concentrations relevant to the studies; the short-term EC50 and LC50 values for these substances are in excess of 1000 mg/l (OECD, 2004a - SIDS for methanol, CAS 67-56-1, OECD, 2004b - SIDS for ethanol, CAS 64-17-5).

Table7.1.1 Key physicochemical parameters and ectoxicological data for the registered and surrogate substances.

CAS Number

116912-64-2

23779-32-0

Chemical Name

Ureidopropyltrialkoxysilane,

mixed methoxy and ethoxy esters

[3-(Triethoxysilyl)propyl]urea

Composition

Multi constituent substance

Mono constituent substance

Constituents

1.      [3-(Trimethoxysilyl)propyl]urea

2.      [3-(Dimethoxyethoxysilyl)propyl]urea

3.      [3-(Methoxydiethoxysilyl)propyl]urea

4.      [3-(Triethoxysilyl)propyl]urea

n.a.

Si hydrolysis product

[3-(trihydroxysilyl)propyl]urea

[3-(trihydroxysilyl)propyl]urea and 3-Ureidopropylsilanetriol

Molecular weight

1.      222.31 g/mol

2.      236.34 g/mol

3.      250.36 g/mol

4.      264.39 g/mol

264.39 g/mol

log Kow (parent)

1.      -0.2

2.       0.3

3.       0.8

4.       1.3

1.3

log Kow (silanol hydrolysis product)

-3.3

-3.3

Water sol (parent)

1.      240 000 mg/l

2.        74 000 mg/l

3.        23 000 mg/l

4.          7 000 mg/l

7 000 mg/l

Water sol (silanol hydrolysis product)

1 000 000 mg/l

1 000 000 mg/l

Vapour pressure (parent)

30.3±1.5 Pa (20 °C) (mixture)

0.0031 PA (20 °C)

Hydrolysis t1/2

at pH 7 and 25°C

1.      <2.4 h

2.      <2.4 h

3.      ≥2.4 h

4.      n.d.

20.6 h (22.5°C)

Hydrolysis t1/2

at pH 4 and 25°C

1.      <<2.4 h

2.      <<2.4 h

3.      <<2.4 h

4.      n.d.

0.6 h (22.5°C)

Hydrolysis t1/2

at pH 7 and 37.5°C

1.      0.88 h

2.      0.88 h

3.      0.88 h

4.      n.d.

6.2 h

Hydrolysis t1/2

at pH 2 and 25°C

1.      <<1.56 min

2.      <<1.56 min

3.      <<1.56 min

4.      n.d.

21.6 s(22.5°C)

Hydrolysis t1/2

at pH 2 and 37.5°C

1.      <<34 s

2.      <<34 s

3.      <<34 s

4.      n.d.

6.5   s

Short-term toxicity to fish (LC50)

>100 mg/l

n/a

Short-term toxicity to aquatic invertebrates (EC50)

>100 mg/l

n/a

Algal inhibition (ErC50 and NOEC)

EC50  of

220 mg/l

NOEC of 10 mg/l

n/a

Long-term toxicity to aquatic invertebrates (NOEC)

n/a

n/a