Methyl-tris acetonoximo-silane

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

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

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Validity criteria fulfilled:

yes

Conclusions:

In this study, under the given conditions, the NOEC was found to be 100 mg/L.

Executive summary:

In a 72 hour acute toxicity study cultures of Selenastrum capricomutum were exposed to WASOX-MMAC2 at nominal concentrations of 100.0, 50.0, 25.0, 12.5 and 6.3 mg test substance equivalents per L nutrient medium under static conditions in accordance with the EU Method C.3 (Algal Inhibition test). The NOEC and EC50 values based on growth rate were 100 mg/L and greater than 100 mg/L, respectively. This toxicity study is classified as acceptable and satisfies the guideline requirements for algae growth inhibition study with Selenastrum capricomutum.

 

Results Synopsis

 

Test Organism:Selenastrum capricomutum

Test Type (Flowthrough, Static, Static Renewal): Static

 

Effect levels:

72 hr EC50: >100 mg a.i./L                

72 hr NOEC: 100 mg a.i./L                  

Endpoint(s) effected: Growth inhibition 

 

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 toxicity of Methyl-tris acetonoximo-silane (MAC) to aquatic algae read-across from WASOX-MMAC2 is available.

Under the conditions of the valid study reported by Bornatowicz (2005), the effect of the test item “WASOX-MMAC2” on the growth of Selenastrum capricornutum has been investigated and gave a EC50 value of greater than 100 mg/L (nominal concentration). Correspondingly the No Observed Effect Concentration (NOEC) was 100 mg/L (nominal concentration). This study showed that there were no toxic effects at highest tested concentration. This information is used in a read-across approach in the assessment of the target substance Methyl-tris acetonoximo-silane (MAC).

Key value for chemical safety assessment

EC10 or NOEC for freshwater algae:

100 mg/L

Additional information

The information on WASOX-MMAC2 is used in a read-across approach in the assessment of Methyl-tris acetonoximo-silane (MAC).

For details on the read across justification refer to the read across statement in IUCLID section 13.