Ethoxytrimethylsilane

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

activated sludge respiration inhibition testing

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

Please refer to analogue justification provided in IUCLID section 13.

Reason / purpose for cross-reference:

read-across source

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

6 670 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Conclusions:

An EC50 value of 6670 mg/L (nominal) for toxicity to microorganisms was determined in a reliable study conducted with a suitable source substance according to an appropriate test protocol, and in compliance with GLP.

Reference 2

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1991-12-09 to 1991-12-10

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study was conducted according to an appropriate OECD test guideline, and in compliance with GLP.

Qualifier:

according to guideline

Guideline:

ISO 8192 (Water quality - Test for inhibition of oxygen consumption by activated sludge for carbonaceous and ammonium oxidation)

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

GLP compliance:

yes

Analytical monitoring:

no

Vehicle:

no

Test organisms (species):

activated sludge

Details on inoculum:

- Source: Laboratory treatment plant (taken 06/12/1991)

- Pretreatment: None

Limit test:

no

Remarks on exposure duration:

Not specified, guideline says 30 min to 3hr

Nominal and measured concentrations:

1000, 1800, 3200, 5600, 10000 mg/l

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

6 670 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Results with reference substance (positive control):

Report states that respiration rate of 3,5 dichlorophenol was checked as a reference, but no results given.

Test substance concentration (mg/l)	Respiration rate (mg O2/l/h)	% Inhibition respiration rate
1000	39.0	0.0
1800	39.0	0.0
3200	34.0	5.6
5600	21.0	41.7
10000	8.6	76.1

 

Conclusions:

An EC50 value of 6670 mg/L (nominal) for toxicity to microorganisms was determined in a reliable study conducted according to an appropriate test protocol, and in compliance with GLP.

Description of key information

EC50: 6670 mg/L (ISO 8192)

Key value for chemical safety assessment

EC50 for microorganisms:

6 670 mg/L

Additional information

There are no data available on toxicity to activated sludge microorganisms for ethoxytrimethylsilane (CAS 1825-62-3). In accordance with Regulation (EC) No 1907/2006 Annex XI, 1.5 “Grouping of substances and read-across” and in accordance with the read across assessment framework (RAAF, ECHA 2017) a read-across from the hydrolysis product trimethylsilanol (CAS 1066-40-6) has been applied to support the environmental hazard assessment of ethoxytrimethylsilane. Details on the read across justification can be found in the attached justification in the respective target entry and in the overall justification for grouping of substances attached in IUCLID Section 13.
The study with the analogue substance was performed according to ISO 8192 (GLP) with test concentrations up to 10000 mg/L. Activated sludge was used as inoculum. Inhibition of total respiration was recorded resulting in an EC50 of 6670 mg/L. Based on the result from the hydrolysis product, ethoxytrimethylsilane is not assumed to inhibit the degradation process in sewage treatment plants.