5-amino-3-[[4-[[4-[[4-anilino-2-hydroxyphenyl]azo]phenyl]amino]-3-sulphophenyl]azo]-4-hydroxynaphthalene-2,7-disulphonic acid, sodium salt

Toxicity to aquatic algae and cyanobacteria

Description of key information

ErC50 (72 h): 17.4 mg/l (nominal)

EbC50 (72 h): 8.4 mg/l (nominal)

Key value for chemical safety assessment

EC50 for freshwater algae:

17.4 mg/L

EC10 or NOEC for freshwater algae:

3.2 mg/L

Additional information

The following data was obtained for the Similar Substance 01. It is expected that the Target substance will present similar effect levels to algae. Justification for the use of a read-across approach is provided in Section 13 of IUCLID.

The influence of the Similar Substance 01 on the growth of the green alga Scenedesmus subspicatus was investigated in a 96-hour static test, according to the OECD Guideline No. 201. The nominal concentrations tested were 1.0, 3.2, 10.0, 32.0 and 100.0 mg test substance/l and a control without any additions. Test item has an inhibition effect on the growth of Scenedesmus subspicatus first on the concentration of 10.0 mg test substance/l; the EC0 was determined to be 3.2 mg test substance/l. The EbC50 at 72 hours resulted to be 8.4 mg test substance/l, while the ErC 50 (72 h) was indicated to be 17.4 mg test substance/l. The test substance concentration in the analysed stock solution amounted to 105.0 % of the nominal value, in the analysed test media of the nominal concentrations 10 and 100 mg/l, test substance concentrations were measured corresponding to between 85.3 and 99.5 % of the nominal values. In the lowest concentration of 1.0 mg/l, the test substance concentration decreased from 87 % of the nominal value at the start of the test to 56 % after 96 hours of exposure. Since this test concentration was not relevant to the reported results and in the higher test concentrations, the test substance was sufficiently stable under test conditions, the reported results are related to the nominal concentrations of the test substance).

A second test on the Similar Substance 01 is available. The effects of the test item on the growth of a green algae species, Pseudokirchneriella subcapitata, was tested in a 72 - hour test according to the OECD guideline 201. Six different concentrations of the substance, ranging from 1 - 48 mg/l, and a control, without test addition, were in contact for 72 hour with the algae. The cells were counted after 72 hours of exposure. The growth inhibition percentage was estimated by the difference between the biomass in the start and the biomass at the end of the test. pH was measured at the test initiation and at the end. The EC50, after 72 hours, resulted to be 10 mg/l (nominal), based on active ingredient.