Acid Red 131:1

Toxicity to aquatic plants other than algae

Description of key information

100 mg/l < ErC50 < 1000 mg/l

EyC50: ca. 100 mg/l

Key value for chemical safety assessment

EC50 for freshwater plants:

100 mg/L

EC10 or NOEC for freshwater plants:

10 mg/L

Additional information

The evaluation of toxicity to aquatic plants of the substance has been based on a study conducted on the Similar Substance 02. The complete hypothesis and justification for the read across approach has been attached in section 13.

The Read across approach here discussed is based on the structural similarity of the two main components of target and source substances, on their similar composition and biodegradation potential, in order to fulfil eco-toxicological information requirements (toxicity to aquatic plants other than algae).

The inhibitory effects based on the average specific growth rate and the yield (absolute increase in plant size) to the duckweed Lemna minor was

investigated over a period of 7 days.

The test was performed at nominal concentrations of 11.4, 114 and 1140 mg/l of test substance, corresponding to 10, 100 and 1000 mg/l of the active ingredient (AI).

No chemical analysis of the test concentrations was conducted. The determination of the effect concentrations was based on the nominal concentrations of the active ingredient assuming the test item to be stable in medium for the whole test period.

For the endpoint frond number and with respect to growth rate inhibition, the following effects as compared to the untreated controls were observed: 19 % at 100 mg/l and 75 % at 1000 mg/l. No significant effects were observed at 10 mg/l, as determined by Dunnet’s test.

For the endpoint frond number and with respect to yield inhibition, the following effects as compared to the untreated controls were observed: 18 % at 10 mg/l, 41 % at 100 mg/l and 92 % at 1000 mg/l.

Based on these data the median effect concentrations to Lemna minor with respect to growth rate (ErC50) and to yield (EyC50) for the endpoint frond

number was estimated to be 100–1000 and about 100 mg/l nominal concentration, respectively.

The no-observed-effect concentrations to Lemna minor with respect to growth rate (NOErC) and yield (NOEyC) for the endpoint frond number were 10

and <10 mg/l nominal concentration, respectively, as determined by Dunnett's test.

For the endpoint dry weight and with respect to growth rate inhibition, the following effects as compared to the untreated controls were observed: 20 % at 100 mg/l and 67 % at 1000 mg/l. No significant effects were observed at 10 mg/l, as determined by Dunnet’s test.

For the endpoint dry weight and with respect to yield inhibition, the following effects as compared to the untreated controls were observed: 22 % at 10 mg/l, 44 % at 100 mg/l and 90 % at 1000 mg/l.

Based on these data the median effect concentrations to Lemna minor with respect to growth rate (ErC50) and to yield (EyC50) for the endpoint dry

weight was estimated to be about 100 – 1000 and about 100 mg/l nominal concentration, respectively.

The no-observed-effect concentrations to Lemna minor with respect to growth rate (NOErC) and yield (NOEyC) for the endpoint dry weight were 10 and <10 mg/l nominal concentration, respectively, as determined by Dunnett's test.