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Ecotoxicological information

Short-term toxicity to aquatic invertebrates

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Description of key information

48-h EC50 124 mg/L, D. magna, reliability 1 (read-across from CAS 1066-40-6)

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
124 mg/L

Additional information

A 48-h EL50value of 11.8 mg/l and a NOELR of <1.0 mg/l have been determined for the effects of the registered substance on mobility of Daphnia magna based on nominal test substance loading rate. This study has been disregarded because the method used for test media preparation would have led to formation of dimer above its limit of solubility in the system. The test substance could not be detected in solution which may have been due to sampling or analytical practise combined with a relatively high limit of detection/quantification. The dimer formed by condensation of dimethyl(vinyl)silanol is less soluble and more toxic than the free silanol (the dimer, 1,1,3,3-tetramethyl-1,3-divinyldisiloxane, CAS 2627-95-4, has an EC50value for toxicity to Daphnia of >0.1 mg/l). In addition, the test organisms are sensitive to the presence of undissolved silanol condensation products. Both of these factors would have negatively influenced the outcome of this study.

In water, chlorodimethyl(vinyl)silane hydrolyses very rapidly to dimethyl(vinyl)silanol, therefore good quality data for an appropriate structural analogue of this silanol, trimethylsilanol (CAS 1066-40-6), have been read across. The other hydrolysis product is hydrogen chloride.

A 48-h EC50value of 124 mg/l has been determined for the structurally analogous substance trimethylsilanol (CAS 1066-40-6).

The potential for toxicity caused by the vinyl group has also been considered. Data for trimethoxyvinylsilane indicate that the vinyl fraction of the registered substance is of very low short-term toxicity to aquatic invertebrates (48-h EC50: 168.7 mg/l).

Refer to the discussion in the Section 6 endpoint summary for further discussion of the approach to chemical safety assessment for this registration substance, and justification for read-across used.