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Ecotoxicological information

Toxicity to aquatic plants other than algae

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Description of key information

EC50 (7d) > 100 mg/l (nominal), based on growth rate of frond number

Key value for chemical safety assessment

EC10 or NOEC for freshwater plants:
31.3 mg/L

Additional information

There are no information about the toxicity potential to aquatic plants of Acid Red 336, thus the available data on structural analogous Similar Substance 02 have been taken into account. The read across approach can be considered as reliable and suitable for the purpose; details and explanations are included in the report attached to the IUCLID section 13.

The potentisl effects of the Similar Substance 02 were evaluated in a growth inhibition test using the aquatic plant Lemna gibba (duckweed). A semi-static test with nominal concentrations of 0 (control), 0.954, 3.05, 9.77, 31.3 and 100 mg/l was performed.

The initial mean measured concentration of test item in the test item solutions was 99 % of nominal. The overall mean concentration of fresh and aged samples was 96 % of nominal. Toxicological endpoints were evaluated using nominal concentrations of the test item.

On day 3 slightly shorter roots were observed at 31.3 mg/l. At 100 mg/l the fronds were curved and coloured red and offshoots were smaller. The roots were shortened. On day 5 shorter roots and smaller offshoots were observed at 31.3 mg/l. At 100 mg/l fronds were curved and coloured red with smaller offshoots. The roots were shortened. On day 7 partly shorter roots were observed at 9.77 mg/l. At 31.3 mg/l the fronds were partly coloured red with smaller offshoots. The roots were shortened. At 100 mg/l fronds were curved and coloured red with smaller offshoots. The roots were shortened.

Significant inhibitory effects were determined for yield of frond numbers and for growth rate of frond numbers at 100 mg/l (nominal): after 7 days of exposure, an inhinibition of the 76.2 % was recorded, based on the frond number yield. At the same concentration, the inhibition of the growth rate estimated on the basis of the frond number was 48.4 %. At the nominal concentration of 100 mg/l, data on yield and growth rate of dry weight indicated an inhibition of 86.4 % and 64.9 %, respectively.