Methyl-tris acetonoximo-silane

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

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

Adequacy of study:

key study

Justification for type of information:

The source compound Wasox-MMAC2 (mixture of: propan-2-one-O,O'-(methoxymethylsilandiyl)dioxime; propan-2-one-O-(dimethoxymethylsilyl)oxime; propan-2-one-O,O',O''-(methylsilantriyl)trioxime, EC No. 460-110-3) is considered a suitable read across partner for the target substance MAC (CAS 2594-75-4). This read-across is based on the hypothesis that source and target substances have similar toxicological properties because:

- structural similarity of the target and the source substances (the presence or absence of additional functional groups or substituents that could influence the behaviour of a chemical),

- similarity in physico-chemical profile of the source and target substances (rapid decomposition in water under cleavage of the same substance (acetone oxime)).

Both substances are similar in terms of the substitution pattern at the silicon atom (i.e. acetoneoximo and methyl group(s)). Both substances exhibit consequently similar physico-chemical properties (rapid decomposition in water, decomposition upon heating to determine boiling point) and exhibit also similar properties in terms of hydrolysis, resulting in the release of the same decomposition product (here: acetone oxime).

Reason / purpose for cross-reference:

read-across source

Key result

Parameter:

% degradation (CO2 evolution)

Value:

0.32

Sampling time:

28 d

Details on results:

"WASQX-MMAC2" is not readily biodegradable as the biodegradation reached only 32.1 % after 28 days.

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

The mean degradation rate of WASOX-MMAC2 was 32.1 % after 28 days. Therefore, the test substance is considered to be not readily biodegradable.

Executive summary:

The biodegradation of WASOX-MMAC2 was studied in reconstituted water (pH 7.4 – 7.6) inoculated with activated sludge from a domestic sewage treatment plant. The test substance, was suspended in buffered mineral salts medium at a nominal concentration of 15 mg organic carbon per litre. The experiment was conducted in accordance with the OECD test guideline 301B "CO2 Evolution Test", and in compliance with the OECD-GLP standards. The biodegradability of the test substance was analysed by the determination of carbon dioxide evolution at frequent intervals over a 28d period. The reference substance sodium benzoate was degraded by 81.5 % within 10 days. Degradation in the toxicity control, which contained sodium benzoate and the test substance, was not indicative of an inhibition of the microbial activity by the test substance. The carbon dioxide evolution from the test substance with a nominal concentration of 15 mg Carbon/L reached a maximum of 32.1 % after 28 days of incubation at 21.6 ± 0.5 °C. According to the results of this study, the test substance cannot be classified as readily biodegradable.

This information is used in a read-across approach in the assessment of the target substance.

For justification of read-across please refer to the attached read-across report (see IUCLID section 13).

 

 

Description of key information

To evaluate the biodegradation of Methyl-tris acetonoximo-silane (MAC) read-across from WASOX-MMAC2 is available.

In the CO2 evolution test (modified Sturm test) reported by Weiss-Fuchs (2004), WASOX-MMAC2 is not readily biodegradable (32.1% after 28 days).

This information is used in a read-across approach in the assessment of the target substance MAC.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed