Registration Dossier

Ecotoxicological information

Endpoint summary

Administrative data

Description of key information

Additional information

There are no reliable aquatic toxicity data available for methylsilanetriyl triacetate (CAS 4253-34-3), therefore good quality data for the structurally-related substances, triethoxy(methyl)silane (CAS 2031-67-6) and trimethoxy(methyl)silane (CAS 1185-55-3), have been read across. The data with triethoxy(methyl)silane have been chosen as key.

 

Reliable short-term toxicity tests results are available for freshwater fish (Danio rerio), invertebrates (Daphnia magna) and algae (Pseudokirchnieriella subcapitata) for triethoxy(methyl)silane (CAS 2031-67-6). The relevant short-term values are:

Fish: LC50 (96 h): >500 mg/l nominal concentration or >213.7 mg/l expressed in terms of concentration of the hydrolysis product, methylsilanetriol.

Daphnia: EC50 (48 h): >500 mg/l nominal concentration or >213.7 mg/l expressed in terms of concentration of the hydrolysis product, methylsilanetriol.

Algae: EC50 (72 h): >500 mg/l; NOEC: =500 mg/l nominal concentration or >213.7 mg/l and =213.7 mg/l, respectively, expressed in terms of concentration of the hydrolysis product, methylsilanetriol.

Reliable data for long-term toxicity to Daphnia magna are available for the read-across substance, trichloro(ethyl)silane (CAS 115-21-9). In this test the 21-day NOEC for survival and reproduction was found to be =100 mg/l, nominal concentration.  The test substance very rapidly hydrolyses to ethylsilanetriol and hydrochloric acid. The NOEC expressed in terms of the silanol hydrolysis product, ethylsilanetriol, is =66 mg/l.

 

An activated sludge respiration inhibition 3 hour EC10 value of >100 mg/l expressed in terms of trimethoxy(methyl)silane and >69 mg/L when expressed as the silanol hydrolysis product, methylsilanetriol (nominal) were determined in a reliable study.

 

The rapid hydrolysis of triethoxy(methyl)silane (CAS 2031-67-6 ) (half-life 5.5 h at pH 7 and 20-25 °C) means it is likely that the test organisms in each test were exposed primarily to the hydrolysis products, methylsilanetriol and ethanol. 

 

Refer to IUCLID Section 6 endpoint summary (CSR Section 7.0) for further discussion of the approach to chemical safety assessment and justification for read across.