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Toxicity to microorganisms

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Description of key information

EC10 (3 h) > 100 mg/L (OECD 209) based on read across from CAS 1185 -55 -3

Key value for chemical safety assessment

Additional information

No data on the toxicity of dimethoxymethylsilane (CAS 16881 -77-9) to microorganism are available. Therefore good quality data of the analogue substance, trimethoxy(methyl)silane (CAS 1185 -55 -3) have been read across. Both substances hydrolyse rapidly to the same hydrolysis product, methylsilanetriol. It is therefore considered appropriate to read-across the results from trimethoxy(methyl)silane to the target substance.

Both dimethoxydimethylsilane and trimethoxy(methyl)silane are within an extended analogue group than the analogue group discussed in Section 1.4. Substances within the extended analogue group, are in general not toxic to microorganisms. The extended analogue group concerning the endpoint "toxicity to microorganisms" is subdivided in a number of sub-classes of substances. Read-across is mainly carried out between substances with the same sub-class. Table 7.1.5 presents the data on the toxicity to microorganism, available for the substances within the sub-class of alkoxysilanes, silanols, acetoxysilanes and chlorosilanes, etc, where the Si part is of low-biological reactivity, once hydrolysis has been taken into account. Both trimethoxyoctylsilane and triethoxyoctylsilane are members of this sub-class. Additional information is given in a supporting report attached in Section 13 of the IUCLID dossier.

Table 7.1.5: Data on the toxicity to microorganism available for substances within the relevant sub-class of chemicals

CAS

Name

Result: E(I)C50(mg/l)

Result: NOEC (or EC10/ EC20) (mg/l)

Guideline Number

Test method

Species

Duration

Reliability

001000-50-6

Butylchlorodimethylsilane

>340

 

88/302/EC

ASRI

 

3h

1a

001066-40-6

Hydroxytrimethylsilane

6670

 

OECD 209 and ISO 1892

ASRI

 

Uncertain

1a

001185-55-3

Trimethoxy(methyl)silane

>100

 

OECD 209

ASRI

 

3hr

1a

031795-24-1

Potassium methylsilanetriolate

>100

 

OECD 209

ASRI

 

3 h

1a

087135-01-1

1,6-Bis(trimethoxysilyl)hexane

>1000

 

OECD 209

ASRI

 

3h

1a

017980-47-1

Triethoxyisobutylsilane

>1000

≥1000

OECD 209

ASRI

 

3h

1a

005894-60-0

Trichloro(hexadecyl)silane

>1000

≥1000

OECD 209

ASRI

 

3h

1a

016415-12-6

Hexadecyltrimethoxysilane

>1000

 

OECD 209

ASRI

 

3 hr

1a

002943-75-1

Triethoxyoctylsilane

>1000

 

OECD 209

ASRI

 

3 hr

1a

016068-37-4

4,4,7,7-tetraethoxy-3,8-dioxa-4,7-disiladecane

>8000

8000

DIN 38 412, Part 8 (Pseudomonas cell multiplication inhibition test)

growth inhibition test

P putida

16 h

1c

035435-21-3

Triethoxy(2,4,4-trimethylpentyl)silane

>100

 

OECD 209

ASRI

 

3hr

1a

018395-30-7

Trimethoxy(2-methylpropyl)silane

 

EC10 1.3 ml/l

Huls AG method

oxygen consumption

P putida

5.8 h

2c -don't use to derive PNEC

142877-45-0

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

>1000

1000

OECD 209

ASRI

 

3 hr

1a

013154-25-1

Chlorotri(3-methyl-propyl)silane

>1000

100

OECD 209

ASRI

 

3 hr

2b

126990-35-0

Dicyclopentyldimethoxysilane

>water solubility

 

OECD 209//EU C11/Huls AG method (WOE)

ASRI/ASRI/oxygen consumption P putida

 

3 hr

1a/1a/2c

139147-73-2

Silane, dichlorodicyclopentyl-

>100

 

OECD 209

ASRI

 

3 hr

1a


The respiration inhibition was tested in a study (2009) with the read across substance trimethoxy(methyl)silane (CAS 1185 -55 -3). The test was conducted according to GLP standards and the OECD guideline 209. The 3 -h EC50 and EC10 was found to be > 100 mg/L (nominal).

On the basis of the read across results, dimethoxymethylsilane (CAS 16881 -77-9) is considered of low-toxicity to activated sludge microorganisms.