Carbamic acid, N-[(dimethoxymethylsilyl)methyl]-, methyl ester

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:

23 Jul - 20 Aug 2002

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

GLP compliance:

yes (incl. QA statement)

Remarks:

Hessisches Ministerium für Umwelt, Landwirtschaft und Forsten

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: Domestic sewage treatment plant Groß-Zimmern, Germany
- Laboratory culture: no
- Preparation of inoculum for exposure: The activated sludge was washed by centrifugation and the supernatant liquid phase was decanted. The solid material was resuspended in tap water and again centrifuged. This procedure was repeated twice. An aliquot of the final sludge suspension was weighed, dried and the ratio of the wet sludge to its dry weight was determined. Based on this ratio, calculated aliquots of washed sludge suspension, corresponding to 1.5 g dry material/L were mixed with test water and then aerated until use.
- Concentration of sludge: 30 mg suspended solids/L
- Water filtered: no

Duration of test (contact time):

28 d

Initial conc.:

25.5 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: according to guideline with deionised water
- Test temperature: 21 - 22 °C
- pH: 7.6 (measured at start); 7.6 - 7.9 (end of the test)
- Suspended solids concentration: 30 mg/L
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: Manometric Test System with test flaskscontaining a volume of 500 mL in a climate chamber.
- Measuring equipment: The change of pressure in the test flasks was measured by means of a Manometric method (BSB/BOD-Sensor-System, Aqualytic, Neu Isenburg, Germany) each day.
- Method used to create aerobic conditions: continuous stirring
- Details of trap for CO2 and volatile organics if used: Evolved CO2 was absorbed in an aqueous solution (45%) of potassium
- Test performed in closed vessels due to significant volatility of test substance: no

SAMPLING
- Sampling frequency: O2 concentration was measured each day
- Sampling method: Manometric method (BSB/BOD-Sensor-System, Aqualytic, Neu Isenburg, Germany)

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes, 2 replicates
- Abiotic sterile control: yes, 2 replicate
- Toxicity control: yes, 1 replicate
- Reference substance: yes, 1 replicate

Reference substance:

aniline

Parameter:

% degradation (O2 consumption)

Value:

19.5

Sampling time:

28 d

Remarks on result:

other: Mean of two replicates based on ThOD NH4

Parameter:

% degradation (O2 consumption)

Value:

15.5

Sampling time:

28 d

Remarks on result:

other: Mean of two replicates based on ThOD NO3

Results with reference substance:

82% after 14 d based on ThOD NH4 60% pass level was reached.

The toxicity control attained 56% degradation after 14 d. Thus, the test substance is not inhibitory to the inoculum. In the abiotic control, no oxygen demand was determined.

Table 1: Percentage biodegradation (BOD/ThOD NH4) of test item, of aniline and of the toxicity control

Time [d]	Percentage biodegradation
	Test substance		Aniline	Toxicity control
	Flask 1	Flask 2
1	-2	-2	-1	-1
2	7	4	-2	5
3	7	5	-3	7
4	11	9	6	43
5	15	13	58	45
6	15	13	61	47
7	17	14	65	49
8	23	20	71	51
9	23	20	74	52
10	23	21	78	53
11	26	23	80	53
12	26	23	82	54
13	27	24	81	55
14	26	22	82	56
15	26	23	82	57
16	25	23	84	58
17	26	24	84	58
18	26	23	84	58
19	24	21	85	59
20	23	21	84	58
21	23	23	86	58
22	23	23	86	60
23	23	23	90	60
24	23	23	92	60
25	23	21	93	59
26	21	20	92	58
27	22	21	94	58
28	20	19	94	58

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

A biodegradation result of 19.5% in 28 days (ThOD) was determined in a reliable study conducted according to an appropriate test protocol, and in compliance with GLP.

Description of key information

Not readily biodegradable: 15.5 - 19.5% after 28 d (O2 consumption, OECD 301 F, EU C.4-D)

Key value for chemical safety assessment

Biodegradation in water:

not biodegradable

Type of water:

freshwater

Additional information

The target substance methyl-N-{[dimethoxy(methyl)silyl]methyl}carbamate (CAS 23432-65-7) hydrolyses within the timescale of a ready biodegradation test to form methyl-N-{[dihydroxy(methyl)silyl]methyl}carbamate and methanol (DT50 = 1.9 h at pH 7 and 20 - 25 °C).

The available study investigating the ready biodegradability of methyl-N-{[dimethoxy(methyl)silyl]methyl}carbamate (CAS 23432-65-7) was performed according to OECD guideline 301 F and under GLP conditions. The inoculum (non-adapted activated sludge from a sewage treatment plant) was exposed for 28 days to the test substance and biodegradation was calculated based on O2 consumption. A biodegradation of 15.5 - 19.5% (O2 consumption) was recorded after the exposure period. Thus, the substance is not readily biodegradable according to OECD criteria. Because the substance hydrolyses rapidly in contact with water (DT50: 1.9 h at 20 - 25 °C, pH 7), the result from this study mainly reflects the biotic degradation of the hydrolysis products. The alcohol hydrolysis product methanol is known to be readily biodegradable (OECD SIDS, 2004). Thus, the final result is mainly attributed to the silanol hydrolysis product methyl-N-{[dihydroxy(methyl)silyl]methyl}carbamate which is considered not to be readily biodegradable according to the OECD criteria based on the results of the study. 

References:

OECD SIDS, 2004: SIDS Initial Assessment Report for Methanol, SIAM 19, Berlin, Germany, 19-22 October 2004, Methanol, CAS 67-56-1