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Ecotoxicological information

Short-term toxicity to aquatic invertebrates

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Description of key information

Short-term toxicity to invertebrates: 48-hr EC50 6.7 mg/l (measured as TOC) (EC Guideline 92/69/EWG C2). The EC50 is equivalent to 5.3 mg/l when expressed in terms of the silanol hydrolysis product.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates
Effect concentration:
5.3 mg/L

Additional information

A 48-h EC50 value of 6.7 mg/l and NOEC of 2.7 mg/l (measured as TOC) have been determined for the effects of the registration substance on mobility of Daphnia magna. In view of the test media preparation method and exposure regime it is likely that the test organisms were exposed predominantly to the hydrolysis products of the tested substance.

It is evident from the low recovery (as DOC) that a significant proportion of the test material was removed by filtration, and at the loading concentration used in preparation of stock, it is expected that oligomers and/or cross-linked aggregates may have been present to some extent, which would be consistent with this. While this is an uncertainty, it is considered that the study results in terms of geometric mean measured concentrations are suitable to be used (with caution), with effects attributed in principle to intrinsic ecotoxicity of silanol. The results may be expressed in terms of concentration of the hydrolysis product, 3-(trihydroxysilyl)propanethiol, by applying a molecular weight correction: (MW of silanol=154.26 / MW of parent=196.34) * 6.7 = 5.3 mg/l.

The reliability of two other EC50 values of 4 and 84 mg/L, that were obtained from the open literature, could not be determined.

Refer to the discussion in the Section 6 endpoint summary (Section 7.0 of CSR) for further discussion of the approach to chemical safety assessment for this registration substance.