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Diss Factsheets

Ecotoxicological information

Sediment toxicity

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sediment toxicity: long-term
Data waiving:
other justification
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Description of key information

The substance hydrolyses rapidly and its hydrolysis product has a log Kow < 3. Therefore, partitioning to the sediment compartment is expected to be minimal. Furthermore, in accordance with Annex XI, Section 3, exposure of aquatic organisms to dimethoxydimethylsilane was assessed as not significant (RCR << 1).

Key value for chemical safety assessment

Additional information

In accordance with Annex XI, Section 3, exposure of aquatic organisms to dimethoxydimethylsilane is not significant. Furthermore, the hazard assessment based on acute aquatic toxicity data shows no toxicity towards aquatic organisms among all three trophic levels (all acute effect values, i.e. E(L)C50s were > 100 mg/L). Additionally, chronic toxicity tests on aquatic invertebrates and algae are available, which showed no effects up to the highest concentrations tested (21-day NOEC ≥ 12.6 mg/L (daphnia), 72-h NOErC ≥ 118 mg/L (algae)). The substance is well soluble and thus, greater toxicity in additional long-term tests is unlikely. Even though no hazards were identified in acute and chronic aquatic studies, PNECs were derived for the purpose of risk characterization, using the threshold value of 12.6 mg/L obtained in the chronic daphnia study in combination with standard safety factors as outlined in ECHA guidance R.10. As the substance hydrolyses rapidly, the environmental hazard assessment, PNEC derivation and risk characterization is based on the silanol hydrolysis product following a worst case approach. The other hydrolysis product, methanol, is known for its absence of environmental toxicity and aquatic effect values are all well above 100 mg/L for methanol (OECD SIDS, 2004). The risk characterization for the silanol hydrolysis product indicated no risk to the aquatic environment (RCR < < 1). For detailed information on the risk assessment please see the attached documentation.


OECD SIDS, 2004: SIDS Initial Assessment Report for Methanol, SIAM 19, Berlin, Germany, 19-22 October 2004, Methanol, CAS 67-56-1