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Ecotoxicological information

Short-term toxicity to fish

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Description of key information

A 96-hour LC50 values of 55 mg/l has been determined for the effects of the test substance on mortality of Cyprinus carpio. It is likely that the test organisms were predominantly exposed to the hydrolysis products of the substance.

Key value for chemical safety assessment

Additional information

Several studies on the short-term toxicity of the substance to fish are available. LC50 values from experimental studies vary between 4.9 mg/l and 276 mg/l. Ecotox testing for this substance is complicated by the hydrolysis and condensation reactions of the substance.[3-(2,3-epoxypropoxy)propyl]trimethoxysilane is susceptible to hydrolysis of both the trimethoxy and epoxide groups. The trisilanol formed by hydrolysis of the trimethoxy group will undergo condensation reactions to form siloxane dimers, oligomers and polymers, which may precipitate and have physical effects on the test organisms. The study giving a result of 4.9 mg/l (Hüls, 1994) is given reliability 4 and disregarded because insufficient information is available regarding test media preparation and the chemical species present in the test medium during the test. The next lowest LC50 is 55 mg/l (Infracor Degussa Group 1996). The measured hydrolysis half-life of the substance is 6.5 h at pH 7 and 25°C; therefore, it is the hydrolysis product that is relevant for risk assessment.