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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

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

Key value for chemical safety assessment

Additional information

Experimental data were not available for methyl-N- [3-(trimethoxysilyl)propyl]carbamate (CAS 23432-62-4), therefore read across from the comparable substance, methyl-N-{[dimethoxy(methyl)silyl]methyl}carbamate (CAS 23432-65-7) was deemed acceptable for assessment.

Both methyl-N- [3-(trimethoxysilyl)propyl]carbamate (CAS 23432-62-4) and methyl-N-{[dimethoxy(methyl)silyl]methyl}carbamate (CAS 23432-65-7) are within an analogue group of substances within which, in general, there is no evidence of any significant biodegradation. Substances within this wider analogue group, in general, exhibit no evidence of any significant biodegradation once hydrolysis and subsequent biodegradation of alkoxy/acetoxy groups has been taken into account.

It is therefore considered valid to read-across the results for methyl-N {[dimethoxy(methyl)silyl]methyl}carbamate (CAS 23432-65-7) to fill the data gap for the registered substance. This wider analogue group for the ready biodegradability 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.

The table below presents ready biodegradation data available for substances within the sub-class of the III-10 structural class: carbamates.

Ready biodegradation data available for substances within the relevant sub-class of chemicals

CAS

Name

Readily biodegradable? Yes/No

Result: Biodegradation after 28 days

Guideline

Reliability

Corrected % biodegradation once alkoxy/acetoxy biodegradation is accounted for

023432-65-7

Methyl-N-{[dimethoxy(methyl)silyl]methyl}carbamate

No

19-20%

OECD 301F

1a

-13

023432-64-6

Carbamic acid, [(trimethoxysilyl)methyl]-, methyl ester

No

42%

OECD 301F

1a

-8

 

The study with methyl-N-{[dimethoxy(methyl)silyl]methyl}carbamate (CAS 23432-65-7) was performed according to EU C.4-D (GLP; Hertl, 2002). Since the substance is expected to hydrolyse 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 hydrolysis products are methyl-N-{[dihydroxy(methyl)silyl]methyl}carbamate und methanol. After 28 d a degradation of 15.5 - 19.5% (O2 consumption) was recorded. Methanol is known to be readily biodegradable (OECD, 2004). Thus, the final result is mainly attributed to the second hydrolysis product methyl-N-{[dihydroxy(methyl)silyl]methyl}carbamate which is considered not to be readily biodegradable according to the OECD criteria. The study is considered to be reliability 1 (reliable without restrictions); the read across of the result is considered to be reliability 2 (reliable with restrictions).