(3-chloropropyl)dimethoxymethylsilane

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1997-01-23 to 1997-02-10

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

other: EC Guideline: 88/302/EC (30.5.1988)

GLP compliance:

yes

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

Activated sludge from Marl-West (Lippeverband) sewage treatment plant. Suspended solids: 2.75 g/l activated sludge

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

3 h

Test temperature:

At the beginning of incubation 18 - 19.5 °C

During the determination of oxygen content 19.2 - 20 °C

Nominal and measured concentrations:

Nominal concentrations: 180, 240, 300, 360, 420 mg/L

Details on test conditions:

Test substance, synthetic sewage (16 mL), inoculum (200 mL). Total volume 500 ml.

Reference substance (positive control):

yes

Remarks:

3, 5, Dichlorophenol

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

400 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Key result

Duration:

3 h

Dose descriptor:

EC10

Effect conc.:

197 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Table 1 % inhibition

Substance ID / Conc.	Time period of O2 measurement (minutes)	Start value mg O2/L	End value mg O2/L	Mg O2/L*h	% Inhibition	pH before O2 Measurement
CPMDCS 480 mg/L	7.5	8.21	7.17	8.32	69.2	6.3
CPMDCS 360 mg/L	7	6.92	5.1	15.6	42.2	7
CPMDCS 300 mg/L	8	7.21	4.43	20.85	22.8	7.3
CPMDCS 240 mg/L	8	6.91	3.9	22.58	16.4	7.4
CPMDCS 180 mg/L	7	7.01	4.14	24.6	8.9	7.7
DCP 5 mg/L	8	7.87	5.89	14.85	45	8.5
DCP 15 mg/L	7.5	8.41	7.29	8.96	66.8	8.5
DCP 30 mg/L	7.5	8.72	8.03	5.52	79.6	8.5
Control RC1	6.5	7.67	4.83	26.22		8.4
Control RC2	6.5	7.63	4.62	27.78		8.3
Sum RC1+ RC2				54

 

Validity criteria fulfilled:

yes

Conclusions:

An activated sludge respiration inhibition 3hr EC50 value of 400 mg/L and EC10 value of 197 mg/L were determined in a reliable study conducted according to an appropriate test protocol, and in compliance with GLP.

Description of key information

Toxicity to microorganisms: Activated sludge respiration inhibition 3-hour EC₅₀ value of 400 mg/l and EC₁₀ value of 197 mg/l (EC Guideline: 88/302/EC), read-across from an analogous substance.

Key value for chemical safety assessment

EC50 for microorganisms:

400 mg/L

EC10 or NOEC for microorganisms:

197 mg/L

Additional information

There are no microorganism toxicity data available for 3-chloropropyl(dimethoxy)methylsilane, therefore good quality data for the analogous substance dichloro(3-chloropropyl)methylsilane (CAS 7787-93-1, EC 232-136-3), have been read across. The submission substance, 3-chloropropyl(dimethoxy)methylsilane, hydrolyses rapidly in contact with water to form 3-chloropropyl(methyl)silanediol and methanol. The read-across substance, dichloro(3-chloropropyl)methylsilane hydrolyses very rapidly in contact with water to form 3-chloropropyl(methyl)silanediol and hydrochloric acid. Both substances hydrolyse rapidly and share the same silanol hydrolysis product; 3-chloropropyl(methyl)silanediol. In view of the rapid hydrolysis of the registered substance, it is the silanol hydrolysis product that is relevant for environmental risk assessment.

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

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.

3-Chloropropyl(dimethoxy)methylsilane and dichloro(3-chloropropyl)methylsilane are within an analogue group of substances within which, in general there is no evidence of significant toxicity to microorganisms.

This group consists of substances containing a number of different functional groups but specific read across is between substances with similar functionality.

The table below presents microorganism toxicity data for substances relevant to 3-chloropropyl(dimethoxy)methylsilane (CAS 18171-19-2, EC 242-056-0).

It is therefore considered valid to read-across the results for dichloro(3-chloropropyl)methylsilane (CAS 7787-93-1) to fill the data gap for the registered substance since the source and target substances generate the same silanol hydrolysis product. Additional information is given in a supporting report (PFA 2013j) attached in Section 13.

Table: Microorganism toxicity data for relevant substances

CAS	Name	Result: E(I)C50 (mg/l)	Result: NOEC (or EC10/ EC20) (mg/l)	Guideline Number	Test method	Species	Duration	Reliability
7787-93-1	Dichloro(3-chloropropyl)methylsilane	400		88/302/EC	ASRI		3 hours	1
2530-87-2	3-chloropropyl(trimethoxy)silane		EC10 1.1 ml/l Note: WS predicted 14000	Huls method	oxygen consumption	P. putida	5 hours	2
5089-70-3	3-chloropropyl(triethoxy)silane		EC10 >2 ml/l	Huls method	oxygen consumption	P. putida	5 hours	2
15267-95-5	3-chloromethyl(triethoxy)silane	>1000	≥1000	OECD 209	ASRI		3 hours	1

 

A 3-hour EC₅₀ value and NOEC value of 400 mg/l and 197 mg/l respectively, have been determined for the effects of dichloro(3-chloropropyl)methylsilane (CAS 7787-93-1) on the inhibition of respiration of wastewater treatment plant bacteria based on nominal concentrations of the substance (Werner, 1997).

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