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Ecotoxicological information

Short-term toxicity to aquatic invertebrates

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Description of key information

EC50 (48-hour): 124 mg/l on mobility/mortality of Daphnia magna, reliability 2, hydroxytrimethylsilane (CAS: 1066-40-6).

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
124 mg/L

Additional information

A 48-hour EL50 value of >100 mg/L and NOELR of <10 mg/L have been determined for the effects of the test substance on mobility of Daphnia magna when tested with adjustment of test medium pH and based on nominal test substance loading rate. The results are above the limit of solubility of the substance, however, due to the rapid hydrolysis and length of test media preparation, the organisms would have been exposed to a fully solubilised hydrolysis product.

The back calculated DOC concentration corresponds to an EL50 of 42 mg/l. It is possible that the discrepancy may be explained by condensation of the hydrolysis product.

The above result is supported by those from tests carried out with hydroxytrimethylsilane (CAS 1066-40-6) a structurally analogous substance to the initial hydrolysis product and with the final hydrolysis product, dimethylsilanediol (CAS 1066-42-8):

  • A 48-hour EC50 value of 124 mg/L and NOEC of <60 mg/L have been determined for the effects of hydroxytrimethylsilane on mobility/mortality of Daphnia magna.
  • A 48-hour EC50 value of >117 mg/L and NOEC of ≥117 mg/L have been determined for the effects of dimethylsilanediol on mobility of Daphnia magna. This result is supported by a QSAR-calculated LC50 value of 50 mg/L.

    These read-across studies are considered to be reliability 1 (reliable without restrictions); however the read across of the results is considered to be reliability 2 (reliable with restrictions).

The result from the test with hydroxytrimethylsilane is considered to be key because it is a non-limit value.