Registration Dossier

Ecotoxicological information

Endpoint summary

Administrative data

Description of key information

Additional information

Reliable acute toxicity tests results are available for freshwater fish (Oncorhynchus mykiss), invertebrates (Daphnia magna) and algae (Pseudokirchnerella subcapitata). LC50 or EC50 values for the three organisms were >110, >122 and >3.6 mg/L respectively when expressed relative to measured test substance concentrations and >200, >200 and >120 mg/L when expressed as nominal test substance concentrations. A NOEC of ≥3.6 mg/L (measured concentration) or ≥120 mg/L (nominal test substance concentration) was determined in the algal test. It is likely that under the flow-through test conditions the fish and invertebrates were predominantly exposed to the test substance. However, under the static conditions employed in the algal test, the test organisms were predominantly exposed to the hydrolysis products of the substance and this is reflected in the low measured concentrations of the substance relative to nominal. To support the chemical safety assessment of the hydrolysis product methylsilanetriol, a 48-h EC50 of >500 mg/L in invertebrates and a 96 -h LC50 of >500 mg/L in fish have been read-across from a structural analogue, triethoxy(methyl)silane, CAS 2031-67-6.

Reliable data for long-term toxicity to Daphnia magna are available for the read-across substance, trichloro(ethyl) silane (CAS 115-21-9). Trichloro(ethyl) silane is a close structural analogue of trimethoxy(methyl)silane, and the hydrolysis half-lives of trimethoxy(methyl)silane and trichloro(ethyl)silane indicate that, under conditions relevant to ecotoxicity assessment, both will hydrolyse to similar hydrolysis products methylsilanetriol and ethylsilanetriol, respectively, over the course of the test.

An activated sludge respiration inhibition 3hr EC10 value of >100 mg/l (loading rate) was determined in a reliable study conducted according to an appropriate test protocol, and in compliance with GLP.