Trisodium bis[2-[[2,4-dihydroxy-3-[(2-methyl-4-sulphophenyl)azo]phenyl]azo]benzoato(3-)]chromate(3-)

Toxicity to microorganisms

Description of key information

The NOEC of the test item is 1000 mg a.i./L, corresponding to 1064 mg test item/L. The test item is not toxic at the concentration of 1000 mg a.i./L, corresponding to 1064 mg test item/L, to activated sludge of a municipal sewage treatment plant. The EC50 of the test item is > 1000 mg a.i./L, corresponding to > 1064 mg test item/L.

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:

1 000 mg/L

Additional information

In a key study a Respiration Inhibition Test with activated sludge according to OECD Guideline No. 209 was carried out with the test item at theDr.U.Noack-Laboratorien, 31157Sarstedt, Germany.Test system was activated sludge of the municipal treatment plant of 31137 Hildesheim, Germany. The test was carried out under static conditions with the substance concentrations 750 and 1000 mg/L (a.i.), corresponding to the nominal test item concentrations 797 and 1064 mg/L. The respiration rates of the control, reference and test item replicates were measured after a contact time of three hours, and the inhibitory effects of the test and reference item were determined in comparison to the control respiration rates. The mean inhibition of respiration for the test item replicates was -9 % and    -5 %.

In order to check the activity of the test system and the test conditions a reference test was carried out with copper (II) sulphate pentahydrate as reference item and the reference toxicity was determined. The EC₅₀-value for the reference item was 115 mg/L.

NOEC and EC-Values of the test item

	EC-values [mg a.i./L]
NOEC	1000
EC20	> 1000
EC50	> 1000
EC80	> 1000

The NOEC of the test itemis1000mg a.i./L. The test item is not toxic at the concentration of1000mg a.i./L to activated sludge of a municipal sewage treatment plant. The EC50of the test item is > 1000 mg a.i./L.