Benzoic acid, 2-hydroxy-, reaction products with formaldehyde, coupled with diazotized 5-amino-8-[[4-[(4-nitro-2-sulfophenyl)amino]phenyl]azo]-2-naphthalenesulfonic acid disodium salt

Toxicity to microorganisms

Description of key information

EC50 (3 h) > 1000 mg/L

Key value for chemical safety assessment

EC50 for microorganisms:

1 000 mg/L

Additional information

The substance was tested in an activated sludge respiration inhibition test following a method similar to the OECD 209 method. During the range finding study the substance was tested at four nominal concentration from 1 to 1000 mg/L during a contact time of three hours. The request for the definitive study was to carry out a limit test during a contact time of three hours at the no observed effect level and not to determine an EC50. Thus, for the definitive test the concentration tested was 1 mg/L and the inhibition was about 5 %. The EC50 (3 h) for the Reference Substance was found to be 11 mg/L. Percentages of inhibition observed at the reference substance concentrations were comparable for range finding study and for definitive study. From this data, it can be evinced that the sensitivity of sludge used should be considered to be normal in both studies.

The EC50 can only be stated as being as being > 1mg/L from the definitive study, as it was not possible to give a higher value from the results of the definitive study alone. However, from the range finding study the EC50 for the test material exceeded 1000 mg/L.