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Sediment toxicity

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Description of key information

Key value for chemical safety assessment

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No sediment toxicity data are available with the registered substance.

In accordance with Column 2 of REACH Annex IX, there is no need to further investigate the effects of this substance in long-term sediment toxicity studies because, as indicated in guidance R.7.8.10 (ECHA 2016), the quantitative chemical safety assessment (conducted according to Annex I of REACH) indicates that the Risk Characterisation Ratio is well below 1, and therefore the risk is already adequately controlled and further testing is not justifiable.

The parent substance is soluble in water to a concentration of 82 mg/L at 20°C and the silanol hydrolysis product, 3-(trihydroxysilyl)propanethiol, is highly water soluble. Both substances have log Kow values <3 and therefore, exposure of and accumulation in the sediment compartment is expected to be low.

The parent substance and hydrolysis product are not adsorbing (based on log Koc 1.4 and 0.29) and have low potential for bioaccumulation (based on log Kow <3 (2.7 and -1.4)). Therefore, the occurrence of more severe toxic effects in the sediment compartment that were not expressed in the aquatic studies would be considered unlikely The PNEC calculated by the Equilibrium Partitioning Method has been determined for the purpose of deriving a chemical safety assessment and the risk characterisation ratios are below 1.

Overall it is concluded that the risk characterisation conclusion is sufficiently conservative in respect of any uncertainties and therefore further testing is not considered necessary.

Details on how the PNEC and the risk characterisation ratio have been derived can be found in IUCLID Section 6.0 and Chapters 7, 9 and 10 of the Chemical Safety Report.