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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

Biodegradation in water, screening tests: 0% in 28 days (OECD 310), read-across from a structurally-related substance

Key value for chemical safety assessment

Additional information

There are no reliable ready biodegradation data available for tripotassium propylsilanetriolate (CAS 93857-00-2), therefore good quality data for the structurally-related substance, hydroxytrimethylsilane (CAS 1066-40-6), have been read across.

Tripotassium propylsilanetriolate and hydroxytrimethylsilane are within a wider analogue group of substancesthan the silanol analogue group discussed in Section 1.3. Substances within this wider analogue group, in general, exhibit no evidence of any significant biodegradation once hydrolysis and subsequent biodegradation of alkoxy/acetoxy groups has been taken into account.

This wider analogue group for the ready biodegradability endpoint consists of a number of sub-classes of substances. However, read-across is carried out between substances with the same sub-class in most cases.

Table 4.1.3 presents ready biodegradation data available for substances within the sub-class (I-2) of alkoxysilanes, silanols, acetoxysilanes and chlorosilanes, etc, where the Si part is of low-biological reactivity, once any hydrolysis is accounted for.Tripotassium propylsilanetriolate and hydroxytrimethylsilaneare members of this sub-class.

It is therefore considered valid to read-across the results for hydroxytrimethylsilane to fill the data gap for the registered substance.


Table 4.1.3Ready biodegradation data available for substances within the relevant sub-class (I-2) of chemicals

CAS

Name

Readily biodegradable? Yes/no

Result: Biodegradation after 28 day

Guideline

Reliability

Corrected % biodegradation once alkoxy/acetoxy biodegradation is accounted for

1066-40-6

Hydroxytrimethylsilane

No

0%

OECD 310

1

0

18748-98-6

Trimethyl(octadecyloxy)silane

No

68%

OECD 301B

1

-18 (i.e.0)

17689-77-9

Triacetoxyethylsilane

Yes

74% in 21 days

EC C4-A

1

-1 (i.e.0)

1067-25-0

Trimethoxypropylsilane

No

54%

Annex V C4-A

1

4

2943-75-1

Triethoxyoctylsilane

No

31.5%

OECD 301D

1

-11 (i.e.0)

16415-13-7

Triethoxyhexadecylsilane

No

43%

MITI

1

16

87135-01-1

1,6-Bis(trimethoxysilyl)hexane

Yes, but not meeting 10-day window

74%

OECD 301B

1

24

None45

Mixture of 1,1- and 1,2-bis(trimethoxysilyl)ethane

Yes

93%

"Biodegradation study of chemical substances by microorganisms and the like " stipulated in "Testing Method for New Chemical Substances etc." ( Kanhogyo No.5, Yakuhatsu 615, 49Kikyoku No.392, July 13, 1974 )

1

18

13154-25-1

Chlorotri(3-methyl-propyl)silane

No

0%

OECD 301B

1

0

35435-21-3

Triethoxy(2,4,4-trimethylpentyl)silane

No

13%

OECD310

1

-30 (i.e.0)

18395-30-7

Trimethoxy(2-methylpropyl)silane

No

36 - 47%

OECD 301B

1

4

142877-45-0

Silane, trimethoxy(1,1,2-trimethylpropyl)-

No

31%

OECD 301D

1

-2 (i.e.0)

17980-47-1

Triethoxyisobutylsilane

Yes

75%

OECD 301D

1

15

126990-35-0

Dicyclopentyldimethoxysilane

No

12%

OECD 301C

1

-5 (i.e. 0)

139147-73-2

Silane, dichlorodicyclopentyl-

No

0.8%

OECD 301D

2

1

17865-32-6

Cyclohexyldimethoxymethylsilane

No

15-17%

OECD 301D

1

-5 (i.e. 0)

None46

t-butoxycyclopentyldimethoxysilane

No

15%

OECD 301C

1

7

98-12-4

Cyclohexyltrichlorosilane

No

0%

OECD 301C

1

0

124-70-9

Dichloro(methyl)(vinyl)silane

No

-6.78%

OECD 301 A

1

0

1067-53-4

Tris(2-methoxyethoxy)vinylsilane

Yes

89%

Annex V C4-A

1

7

2768-02-7

Trimethoxyvinylsilane

No

51%

OECD 301F

1

-9 (i.e. 0)

 

Additional information is given in a supporting report (PFA, 2013f) attached in Section 13 of the IUCLID 5 dossier.

Hydroxytrimethylsilane attained 0% biodegradation in 28 days.