1,1,3,3-tetramethyldisiloxane

Endpoint summary

Additional information

Reliable test data are available for short-term toxicity of the registered substance to aquatic invertebrates. A 48-hour EL₅₀ value of >100 mg/l has been determined for effects on mortality of Daphnia magna based on nominal concentrations. Based on the hydrolysis half-life of the substance (t½ = 11.3 min at pH 7 and 25°C), it must be assumed that hydrolysis occurred.

In addition, due to the rapid hydrolysis of the substance, short-term aquatic toxicity to invertebrates toxicity data are presented for the read-across substances trimethylsilanol (CAS 1066-40-6), a structurally analogous substance to the initial hydrolysis product of the registered substance, and with the final hydrolysis product, dimethylsilanediol (CAS 1066-42-8):

• A 48-hour EC₅₀ of 124 mg/l has been determined for the effects of trimethylsilanol on mortality of Daphnia magna based on mean measured concentrations.
• A 48-hour EC₅₀ of >117 mg/l has been determined for the effects of dimethylsilanediol on immobility of Daphnia magna based on mean measured concentrations
• A 21-day NOEC value of ≥12.6 mg/l and EC50 value of >12.6 mg/l (Time Weighted Average measured concentrations, limit test) have been determined for the effects of dimethylsilanediol on survival, reproduction and growth of Daphnia magna.

There are no short-term data for effects of the registered subsatance on fish and algae. However, data are available from tests carried out with trimethylsilanol (CAS 1066-40-6), a structurally analogous substance to the initial hydrolysis product of the registered substance, and with the final hydrolysis product, dimethylsilanediol (CAS 1066-42-8).

For fish:

• A 96-hour LC₅₀ of 271 mg/l has been determined for the effects of trimethylsilanol on mortality of Oncorhynchus mykiss based on mean measured concentrations.
• A 96-hour LC₅₀ of >126 mg/l has been determined for the effects of dimethylsilanediol on mortality of Oncorhynchus mykiss based on mean measured concentrations.
• A 32-day EC₁₀ of >12 mg/l has been determined for the effects of dimethylsilanediol on larval development of Pimephales promelas based on mean measured concentrations

For algae:

• A 72-hour EC₅₀ value of >1053 mg/l and NOEC of 70 mg/l have been determined for the effects of trimethylsilanol on growth rate of Pseudokirchneriella subcapitata based on initial measured concentrations of the test substance. When expressed relative to mean measured concentrations the equivalent values are >750 mg/l and 50 mg/l.
• A 72-hour EC₅₀ value of >118 mg/l and a NOEC of ≥118 mg/l have been determined for the effects of dimethylsilanediol on growth rate of Pseudokirchneriella subcapitata based on mean measured concentrations.