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Sediment toxicity

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Description of key information

The long-term toxicity to freshwater sediment organisms was determined in a study according to OECD guideline No 225 and in compliance with GLP criteria (BASF, 2016). In this limit test, sediment worms (Lumbriculus variegatus) were exposed to a nominal test substance concentration of 0 (control) and 1000 mg/kg sediment dry weight for 28 days. Artificial sediment was used which contained 5 % peat, 20 % kaolin and 75 % quartz sand. Test substance concentrations in the sediment layer were analytically verified on the days 0, 7 and 28. No specific analysis in the water phase or pore water was carried out because due to the low water solubility of the test item, this parameter is of minor ecotoxicological relevance. The concentrations of the test item in the sediment samples during the test were 94% at day 0, 68% at day 7 and 16% at day 28 of the nominal concentration. Therefore, all effect values are given as nominal. Visual observations of behavioural differences to the controls were recorded three times per week. The endpoints of the study as determined after day 28 were the number of surviving worms per replicate and the total dry biomass of worms per replicate. Living worms were assigned as adult (large complete worms) or offspring (small complete worms with regenerated body regions or incomplete worms), if possible. No mortality of worms was observed in the control and the limit test item concentration after exposure to the test item over 28 days. The total number of worms and thus the reproduction did not statistically significantly differ compared to the control. No evident changes in the worm behaviour or pathological symptoms were observed in the control as welf as in the limit test item concentration during the 28 days of exposure. At test end, the biomass dry weight of the worms was not statistically significantly different at the limit test item concentration 1000 mg/kg sediment dry weight compared to the control. Based on these findings the 28 -d NOEC is determined at 1000 mg/kg sediment dry weight.

Key value for chemical safety assessment

EC10, LC10 or NOEC for freshwater sediment:
1 000 mg/kg sediment dw

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