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Sediment toxicity

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Description of key information

One non-GLP OECD 225 sediment study has been performed on the substance. This test was done to compare sediment toxicity with diamine HT. The results  indicates that the etherdiamine is less toxic to sediment compared to diamine HT. Hence, the read across is supported. Three long term studies are performed on Diamine HT, and the most reliable Lumbriculus study was used as a key valus for the chemical risk assessment.

Key value for chemical safety assessment

EC10, LC10 or NOEC for freshwater sediment:
86 mg/kg sediment dw

Additional information

One study was conducted to support read across for the sediment toxicity using the REACH registered Diamine HT ( Amines, N-C16-18-alkyl (evennumbered) propane-1,3-diamine, EC number 696-364-9) as a source with Etherdiamine (1,3-Propanediamine, N-[3-((C11-14, C13-rich)oxy)propyl]- branched acetate, EC number 931-295-2) as a target.

The performed study showed that the source for the read across (diamine HT), is more toxic to sediment organisms then the target, etherdiamine. Hence, using sediment data from diamine HT for risk assessment of ehterdiamine is by the registrans considered as a worst case, based on the reported NOECs of the two substance (68 mg/kg dw for the source, diamine HT and 134 mg/L dw for the target, etherdiamine).

For the group of diamines, four test results are available regarding the sediment toxicity. However, for this read across, only the three studies performed on Diamine HT was used. The PNEC for the etherdiamine, is derived exactly as the PNEC for the source (diamine HT).

The long term studies were performed with the hydrogenated diamine C16 -18 and were performed withLumbriculus variegatusandCaenorhabditis elegans.The long-term study withCaenorhabditis elegansshowed no effects upto 1000 mg/kg dw. Two long-term tests withLumbriculus variegatuswere performed applying two different spiking approaches. In the first test a solvent was used to spike the test substance on the sand fraction and in the second test the test substance was spiked onto the whole sediment in the water phase at a slightly elevated temperature. In the first test with solvent spiking, a significant difference in reproduction between the normal control and solvent control was observed. It was not clear why this difference was observed but considering to unrealism in using a solvent to spike the test substance it was decided to repeat the test using an environmentally more realistic solvent free spiking procedure of the whole sediment. For this second long-termLumbriculus variegatusa NOEC and EC10 for reproduction was observed of resp. 180 mg/kg dw and 86 mg/kg dw. The NOEC and EC10 based on dry weight of resp 360 and 237 mg/kg dw are higher probably because the moment of splitting of the worms is slightly influenced by the test substance.

The spiking procedure using a solvent to spike the sand fraction is unrealistic for cationic surfactants. Cationic surfactants which may enter surface water are normally sorbed to dissolved organic matter or suspended matter and may redistribute slowly to thermodynamically more favourable sites when available. Quartz sand has a very low CEC and no organic matter. The use of natural sediment spiked without using solvent is far more realistic and could allow a more evenly distribution of the test substance over the sediment. In addition it would allow the ingestion of the test substance more realistically. In addition the solvent apparently had a positive influence on the reproduction which limits the reliability of the result.

Overall, the EC10 from the most reliable Lumbriculs study was used as key value for the chemical safety assessment.