[4-[p,p'-bis(dimethylamino)benzhydrylidene]cyclohexa-2,5-dien-1-ylidene]dimethylammonium m-[[p-anilinophenyl]azo]benzenesulphonate

Toxicity to microorganisms

Administrative data

Endpoint:

activated sludge respiration inhibition testing

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

the study does not need to be conducted because the substance is highly insoluble in water, hence indicating that aquatic toxicity is unlikely to occur

Justification for type of information:

JUSTIFICATION FOR DATA WAIVING

In accordance with Column 2 of REACH Annex VIII, the activated sludge respiration inhibition study (required in Section 9.1.4) does not need to be conducted if there are mitigating factors indicating that microbial toxicity is unlikely to occur, for instance the substance is highly insoluble in water.
Moreover for the assessment of the biodegradation of the dye, a toxicity control on the sewage treatment micro-organisms was performed reaching the conclusion that the test item was not considered to have adverse effects on the sewage treatment micro-organisms used in the test. However, some inhibition of the activated sewage sludge micro-organisms had occurred as the CO2 evolution rates in the test item vessels were significantly lower than those in the control vessel after 28 days. But the difference between extremes of replicate BOD values at the end of the test was less than 20% and therefore satisfied the validation criterion given in the OECD Test Guidelines. Furthermore, the tested concentration during this essay was 25mg/l well above the maximum concentration in the STP estimated during all the lifecycle assessment.
No micobiological toxicity is observed during the biodegradation assay (25mg/l), so adverse effects are unlikely to occur.