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Ecotoxicological information

Toxicity to microorganisms

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Description of key information

The inhibition of the degradation activity of activated sludge is not anticipated.

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:
740 mg/L

Additional information

There are no microorganism toxicity data available for dichloro(diphenyl)silane, therefore good quality data for the structurally-related substance, trichloro(phenyl)silane (98-13-5), have been read across. Both substances hydrolyse to structurally-related silanol hydrolysis products, phenylsilanetriol and diphenylsilanediol. The other hydrolysis product is HCL. Hydrochloric acid is not expected to have adverse effects on microorganisms in a sewage treatment plant, where the pH is maintained within a favourable range but the expected concentrations are low.

Both dichloro(diphenyl)silaneand trichloro(phenyl)silane are within an analogue groupdiscussed in Section 1.4. Substances within this wider analogue group, in general, exhibit no evidence of significant toxicity to microorganisms.

This wider analogue group for the toxicity to microorganisms 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 7.4.2 presents microorganism toxicity data available for substances within the sub-class (III-22) of alkoxysilanes, silanols, acetoxysilanes and chlorosilanes, etc, where greater functional group(s) in side chain after any very rapid hydrolysis has been accounted for. Bothdichloro(diphenyl)silaneand trichloro(phenyl)silaneare members of this sub-class.

 It is therefore considered valid to read-across the results for trichloro(phenyl)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 dossier.

Table 7.4.2: Microorganism toxicity data 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

Duration

Reliability

000098-13-5

Trichloro(phenyl)silane

>1000 mg/l (Phenylsilanetriol >740mg/l) with pH adjustment

≥1000 mg/l (Phenylsilanetriol 740mg/l) with pH adjustment

OECD 209

ASRI

3h

1a

None1

3-(3-Chloro-4-fluorophenyl)propyldimethylchlorosilane

>1000

EC20 177 mg/l

OECD 209

ASRI

3 hr

1a

166255-23-8

4,6-Bis(Carbonylphenyl)-2(3(Triethoxysilyl)propyl)-1,3-Phenylenbisphenylmethanon

>1000

≥1000

OECD 209

ASRI

3hr

1a

250783-08-5

3-[(4'-acetoxy-3'-methoxyphenyl)propyl]trimethoxysilane

>100

0% inhibition up to 100 mg/l test conc

OECD 209

ASRI

3 h

1a

017890-10-7

Benzenamine, N-[(dimethoxymethylsilyl)methyl]-

>1000

 

OECD 209

ASRI

3h

1a

 

An activated sludge respiration inhibition 3hr EC50value of >1000 mg/l (Equivalent to >740 mg/l phenylsilanetriol) and 3hr NOEC value of 1000 mg/l (Equivalent to 740 mg/l phenylsilanetriol) were reported for trichloro(phenyl)silane based on an guideline study (OECD guideline 209 Activated sludge respiration inhibition test). This indicates that the substance was not toxic to waste water (activated sludge) bacteria at a nominal concentration of 1000 mg/l (Equivalent to 740 mg/l phenylsilanetriol).