[3-(2,3-epoxypropoxy)propyl]dimethoxymethylsilane

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1993-08-12 to 1993-09-09

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EU Method C.4-A (Determination of the "Ready" Biodegradability - Dissolved Organic Carbon (DOC) Die-Away Test)

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): primarily communal sewage treatment plant (Marl - East)

- Preparation of inoculum for exposure: washed

- Concentration of sludge: 26.8 g/l

Duration of test (contact time):

28 d

Initial conc.:

9.51 other: mg DOC/l

Based on:

DOC

Parameter followed for biodegradation estimation:

DOC removal

Details on study design:

TEST CONDITIONS

- Test temperature: 21.8-22.2°C

- Continuous darkness: yes


TEST SYSTEM

- Culturing apparatus: 2000 ml Erlenmeyer flask with loose closure of aluminium foil

- Number of culture flasks/concentration: 6 flasks : 2 with test substance, two blanks, two with reference substance.

SAMPLING

- Sampling frequency: 0, 7, 14, 21, 27, 28 days

CONTROL AND BLANK SYSTEM

- Inoculum blank: yes

Reference substance:

benzoic acid, sodium salt

Key result

Parameter:

% degradation (DOC removal)

Value:

37

Sampling time:

28 d

Details on results:

Biodegradation of reference substance was >60% within a 10 day window (100% after 28 days)

Table 1: Dissolved organic carbon levels (mg/l) and calculated % DOC reduction

Type of suspension	0		7		14		21		27		28
	DOC (mg/l)	DOC reduction (%)	DOC (mg/l)	DOC reduction (%)	DOC (mg/l)	DOC reduction (%)	DOC (mg/l)	DOC reduction (%)	DOC (mg/l)	DOC reduction (%)	DOC (mg/l)	DOC reduction (%)
Test sample Replicate 1	9.92	0	7.46	31	6.79	34	7.03	31	5.97	43	6.43	37
Test sample Replicate 2	10.05	0	7.52	31	6.87	34	6.75	35	6.28	40	6.55	37
Median value		0		31		34		33		41		37
Blank mean value	0.48	-	0.96	-	0.57	-	0.49	-	0.55	-	0.48	-
Reference substance Replicate 1	12.05	0	0.99	100	0.77	98	0.91	96	0.70	99	0.46	100
Reference substance Replicate 2	10.71	0	1.04	99	0.76	98	0.45	100	0.57	100	0.51	100
Median value		0		100		98		98		99		100

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

Biodegradation of 37% in 28 days (EU Method C.4-A; DOC) was determined in a reliable study conducted according to an appropriate test protocol, and in compliance with GLP.

Description of key information

Biodegradation in water (screening tests): 37% in 28 days (EU Method C.4-A), read-across from an analogous substance. No significant biodegradation of the silanol hydrolysis product is expected.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Additional information

There are no reliable ready biodegradation data available for [3-(2,3-epoxypropoxy)propyl]dimethoxy(methyl)silane (CAS No. 65799-47-5), therefore good quality data for the structurally-related substance, [3-(2,3-epoxypropoxy)propyl]trimethoxysilane (CAS No. 2530-83-8), have been read across. Both substances hydrolyse in the time scale of the test and have structurally similar silanol hydrolysis products, [3-(2,3-epoxypropoxy)propyl]methylsilanediol and [3-(2,3-epoxypropoxy)propyl]silanetriol respectively.

The other hydrolysis product is methanol in both cases. Methanol is readily biodegradable (OECD 2004).

[3-(2,3-Epoxypropoxy)propyl]dimethoxy(methyl)silane (CAS No. 65799-47-5) and [3-(2,3-epoxypropoxy)propyl]trimethoxysilane (CAS No. 2530-83-8) are within an analogue group of substances within which, in general, there is no evidence of any significant biodegradation once hydrolysis and subsequent biodegradation of alkoxy/acetoxy groups has been taken into account. This analogue group for the ready biodegradability 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 ready biodegradation data for substances within the sub-class III-12 of epoxyalkyl alkoxysilanes. [3-(2,3-epoxypropoxy)propyl]dimethoxy(methyl)silane (CAS No. 65799-47-5) and [3-(2,3-epoxypropoxy)propyl]trimethoxysilane (CAS No. 2530-83-8) are members of this sub-class.

It is therefore considered valid to read-across the results for [3-(2,3-epoxypropoxy)propyl]trimethoxysilane (CAS No. 2530-83-8) to fill the data gap for the registered substance. Additional information is given in a supporting report (PFA, 2013f) attached in Section 13.

Table: Ready biodegradation data available for substances within the relevant sub-class III-12 of chemicals

CAS	Name	Main code	Readily biodegradable? Yes/no	Result: Biodegradation after 28 day		Guideline	Reliability	Corrected % biodegradation once alkoxy/acetoxy biodegradation is accounted for
10217-34-2	Triethoxy-[2-(7-oxabicyclo[4.1.0]hept-3-yl)ethyl]silane	III-12	No		28%	OECD 301D	1	-15
2530-83-8	[3-(2,3-Epoxypropoxy)propyl]trimethoxysilane	III-12	no		37%	Annex V C4-A	1	4
2602-34-8	[3-(2,3-Epoxypropoxy)propyl]triethoxysilane	III-12	no		53%	OECD 301F	1	3

In the study with [3-(2,3-epoxypropoxy)propyl]trimethoxysilane (CAS No. 2530-83-8), 37% biodegradation was observed in 28 days.

[3-(2,3-Epoxypropoxy)propyl]trimethoxysilane (CAS No. 2530-83-8) hydrolyses within the timescale of the ready biodegradation study to [3-(2,3-epoxypropoxy)propyl]silanetriol and methanol. The biodegradation observed in the study is attributable to the biodegradation of the methanol hydrolysis product.

Methanol is readily biodegradable (OECD 2004).

No significant biodegradation is expected for the silanol hydrolysis product.

There is a less reliable study available for [3-(2,3-epoxypropoxy)propyl]trimethoxysilane (CAS No. 2530-83-8) (Prost, 1983) which reports a much higher biodegradation of 90% in 7 days (ISO 7827; DOC). However, the source of inoculum is not stated in the study report, and it is possible that the bacteria were acclimated to the test substance.

References:

OECD (2004). SIDS Initial Assessment Report for SIAM 19, Berlin, Germany, 18-20 October 2004, Methanol, CAS 67-56-1.

PFA (2013f). Peter Fisk Associates, Biodegradation Main Analogue Group report, PFA.300.005.007