Potassium sodium 4,4'-bis[6-anilino-4-[bis(2-hydroxyethyl)amino]-1,3,5-triazin-2-yl]amino]stilbene-2,2'-disulphonate

Toxicity to aquatic algae and cyanobacteria

Description of key information

ErC50 (72h) > 123 mg/l (nominal)

NOEC (72h, growth rate) = 30.8 mg/l (nominal)

Key value for chemical safety assessment

EC50 for freshwater algae:

123 mg/L

EC10 or NOEC for freshwater algae:

30.8 mg/L

Additional information

The toxicity of the substance to aquatic algae was evaluated by considering data on the substance and on the similar substance 3a-A(Na). Justification for Read Across is given in Section 13 of IUCLID.

The toxicity of 3a-A(Na)to the unicellular freshwater green alga Pseudokirchneriella subcapitata was determined according to the principles of OECD 201 and Council Regulation (EC) No. 266/2016/Method C.3 for the determination of the effects on growth rate and yield over a period of 72 hours. The study was conducted under static conditions with an initial cell density of 5416 cells/ml. Five concentrations were tested in a geometrical series with a factor of 2: 7.69 -15.4 -30.8 -61.5 -123 mg test item/l. The concentrations of the test item were analytically verified at the start (0 hours) and at the end of the exposure (72 hours) in all concentration levels and in the control. The measured concentrations in the test solutions at the start of the exposure were in the range of 105 to 117% of the nominal concentrations. At the end of exposure after 72 hours, the measured concentrations in the test item solutions were in the range of 100 to 108% of the nominal concentrations. The effect values of the substance on the growth of the freshwater green alga Pseudokirchneriella subcapitata after 72 hours were determined as follows (based on nominal test item concentrations): The EC50-values for both inhibition of growth rate (ErC50) and yield (EyC50) after 72 hours were > 123 mg/l. The NOEC for growth rate and yield was 30.8 and 7.69 mg/l, respectively.

Supporting data from the subsatnce and from the similar substance are presented as follows:

The acute toxicity of the substance to green algae (Pseudokirchnerella subcapitata) was evaluated in the 72 hours screening test, according to the OECD guideline 201. A single dose was administrated at 100 mg/l causing the growth inhibition of the 2 % (Mätzler P., 1999).

Since analytical identification and sample purity were missing in the study on the substance, the result was confirmed by the outcomes on the analogous substance 3a-A(Na). The substances share the same organic functionalities, but a differrent salifications. This difference has no impact on general water toxicological properties and the percentage and chemical identity of organic impurities are also very similar. Acute toxicity to green algae was evaluated in the 72 hours screening test, according to the OECD guideline 201. A single dose was administrated at 100 mg/l (limit test).

For all tested substances a value of EC50 greater than 100 mg/l was set.

The results obtained in the key study conducted on the similar substance 3a-A(Na) are used for the chemical safety assessment.