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Sediment toxicity

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Description of key information

In accordance with Column 2 of REACH Annex IX the study does not need to be conducted.

Key value for chemical safety assessment

Additional information

Testing for sediment toxicity is not considered necessary because:

 

PNECsediment has been calculated from PNECfreshwater on the basis of the equilibrium partitioning method; the risk characterisation ratios (RCR) based on PNECsediment derived from this method are <1.In accordance with Annex XI, section 2, the long-term toxicity effects studies to sediment dwelling organisms (required in Section 9.5.1) do not need to be conducted as the study is technically not possible. This is due to the very short sediment half-life once desorbed (see Environmental Fate section, Adsorption/Desorption for further details), preventing maintenance of exposure concentrations.

PNECsediment has been calculated from PNECfreshwater on the basis of the equilibrium partitioning method; the risk characterisation ratios (RCR) based on PNECsediment derived from this method are <1.

There are no sediment data available for (Z)-octadec-9-enol (C18 unsaturated - CAS 143-28-2). ECHA guidance on the Integrated Testing Strategy (ITS) for toxicity to sediment organisms (ECHA 2014, R.7b) advises that, as PNECsediment is derived using the equilibrium partitioning method (EPM) and the substance has log Kow >5 (7.07) indicating potential for high adsorption, an additional factor of 10 should be applied on the PEC/PNECsed. If the PEC/PNECsed is then >1, a long-term sediment test as appropriate should be performed, or PNECsediment should be refined.

The LCAAshave a very short sediment half-life once desorbed, thus preventing maintenance of exposure concentrations. This meansthat long-term toxicity testing in sediment is not possible. Therefore sediment hazard assessment is based on the EQPM PNECs derived from the aquatic data.

The aquatic data used to derive the PNECaquatic for (Z)-octadec-9-enol is based on the 21-d EC10value of 0.012 mg/l, for long-term toxicity of pentadecan-1-ol (CAS 629-76-5) to aquatic invertebrates. This substance is used for deriving the aquatic PNEC for alcohols >C15, based on the conclusion in the SIAR that "For substances of chain length greater than C15, no long-term effects would be expected" (for water). The RCRs derived using this approach are only indicative limits, not true values, therefore the PNECaquatic for 9-octadecen-1-ol is a conservative value.