Dichloro(dimethyl)silane

Toxicity to microorganisms

Description of key information

Toxicity to microorganisms: 3 hr EC10 >100 mg/l (OECD 209), read-across from a structurally-related substance, trimethoxy(methyl)silane.

Additional information

There are no microorganism toxicity data available for dichloro(dimethyl)silane (CAS 75 -78 -5), therefore good quality data for the structurally-related substance, trimethoxy(methyl)silane (CAS 1185 -55 -3), have been read across. Both substances have structurally similar silanol hydrolysis products, dimethylsilanediol and methylsilanetriol, respectively. The other hydrolysis products are hydrogen chloride and methanol, respectively.

Methanol does not have adverse effects on microorganisms (OECD, 2004).

Hydrogen chloride is not expected to have adverse effects on microorganisms in a sewage treatment plant, where the pH is maintained within a favourable range.

Dichloro(dimethyl)silane and trimethoxy(methyl)silane are within an analogue group of substances within which, in general, there is no evidence of significant toxicity to microorganisms.

This analogue group for the toxicity to microorganisms endpoint consists of a number of sub-classes of substances

(based on structure/functionality)

with different main codes (used to represent the different sub-classes). However, read-across is carried out between substances with the same main code in most cases.

The table below presents microorganism toxicity 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.

Dichloro(dimethyl)silane and trimethoxy(methyl)silane are members of this sub-class.

It is therefore considered valid to read-across the results for trimethoxy(methyl)silane to fill the data gap for the registered substance.Additional information is given in a supporting report (PFA, 2013j) attached in Section 13 of the IUCLID 5 dossier.

Microorganism toxicity data available for substances within the relevant sub-class I-2 of chemicals

CAS	Chemical Name (CAS Name)	Main code	Guideline Number	Test method	Species	PFA Klimisch code	Year	Duration	Result: E(I)C50 (mg/l)	Result: NOEC (Or EC10/EC20) (mg/l)
1066-40-6	Hydroxytrimethylsilane	I-2	OECD 209 and ISO 1892	ASRI		1a	1992	Uncertain	6670
31795-24-1	Potassium methylsilanetriolate	I-2	OECD 209	ASRI		1a	2009	3 h		EC10 >100 mg/l
139147-73-2	Silane, dichlorodicyclopentyl-	I-2-D-C	OECD 209	ASRI		1a	1997	3 hr	>100
124-70-9	Dichloro(methyl)(vinyl)silane	I-2-D-C	OECD 209	ASRI		1a	2009	3hr	>100 mg/l
126990-35-0	Dicyclopentyldimethoxysilane	I-2-D-Me-M	OECD 209/EU C11/Huls AG method (WOE)	ASRI/ASRI/oxygen consumptionP. putida		1a/1a/2c	1996	3 hr	>water solubility
1000-50-6	Butylchlorodimethylsilane	I-2-M-C	88/302/EC	ASRI		1a	1996	3h	>340
13154-25-1	Chlorotri(3-methyl-propyl)silane	I-2-M-C	OECD 209	ASRI		2b		3 hr	>1000 (nominal, parent)	100 (nominal, parent)
5894-60-0	Trichloro(hexadecyl)silane	I-2-T-C	OECD 209	ASRI		1a		3h	>1000	≥1000 mg/l
75-94-5	Trichloro(vinyl)silane	I-2-T-C	OECD 209	ASRI		1a	2009	3hr	>100 mg/l
1185-55-3	Trimethoxy(methyl)silane	I-2-T-Et-H	OECD 209	ASRI		1a	2009	3hr	>100 mg/l	EC10 >100 mg/l
17980-47-1	Triethoxyisobutylsilane	I-2-T-Et-H	OECD 209	ASRI		1a		3h	>1000mg/l	≥1000 mg/l
2943-75-1	Triethoxyoctylsilane	I-2-T-Et-M	OECD 209	ASRI		1a		3 hr	>1000	≥1000 mg/l
16068-37-4	4,4,7,7-tetraethoxy-3,8-dioxa-4,7-disiladecane	I-2-T-Et-M	DIN 38 412, Part 8 (Pseudomonas cell multiplication inhibition test)	growth inhibition test	P. putida	1c	1994	16 h	>8000 mg/l	8000 mg/l
35435-21-3	Triethoxy(2,4,4-trimethylpentyl)silane	I-2-T-Et-M	OECD 209	ASRI		1a	2009	3hr	>100 mg/l
87135-01-1	1,6-Bis(trimethoxysilyl)hexane	I-2-T-Me-H	OECD 209	ASRI		1a	2009	3h	>1000 mg/l
16415-12-6	Hexadecyltrimethoxysilane	I-2-T-Me-H	OECD 209	ASRI		1a		3 hr	>1000
142877-45-0	Silane, trimethoxy(1,1,2-trimethylpropyl)-	I-2-T-Me-S	OECD 209	ASRI		1a		3 hr	>1000	≥1000 mg/l

 

In the study with trimethoxy(methyl)silane (CAS 1185 -55 -3), an activated sludge respiration inhibition 3h EC₁₀value of >100 mg/l was reported.

The study is considered to be reliability 1 (reliable without restrictions); the read across of the result is considered to be reliability 2 (reliable with restrictions). References: OECD (2004): SIDS Initial Assessment Report for SIAM 19, Berlin, Germany, 18-20 October 2004, Methanol, CAS 67-56-1. PFA, 2013j, Peter Fisk Associates, STP Microorganism toxicity Main Analogue Group report, PFA.300.003.006